Linear Referencing in ArcGIS - MAGTUG · 2 LINEAR REFERENCING IN ARCGIS Most applications that use...

ArcGIS®

9Linear Referencing in ArcGIS®

Copyright © 2002–2004 ESRIAll rights reserved.Printed in the United States of America.

The information contained in this document is the exclusive property of ESRI. This work is protected under United States copyright law and otherinternational copyright treaties and conventions. No part of this work may be reproduced or transmitted in any form or by any means, electronic ormechanical, including photocopying and recording, or by any information storage or retrieval system, except as expressly permitted in writing by ESRI. Allrequests should be sent to Attention: Contracts Manager, ESRI, 380 New York Street, Redlands, CA 92373-8100, USA.

The information contained in this document is subject to change without notice.

DATA CREDITS

Highways and streets map—Maryland Department of Transportation State Highway Administration, Baltimore, Maryland

Transit map—Parsons Brinckerhoff Quade & Douglas, Inc., Los Angeles, California

Railways map—Parsons Brinckerhoff Quade & Douglas, Inc., Los Angeles, California

Oil and gas exploration map—TGS–NOPEC Geophysical Company, Houston, Texas

Pipelines map—M.J. Harden Associates, Inc., Kansas City, Missouri

Water resources map—Center for Research in Water Resources, University of Texas at Austin

Hatching map 1—New York State Department of Transportation, Albany, New York

Hatching map 2—TGS–NOPEC Geophysical Company, Houston, Texas

AUTHORS

Patrick Brennan, Melanie Harlow

U.S. GOVERNMENT RESTRICTED/LIMITED RIGHTSAny software, documentation, and/or data delivered hereunder is subject to the terms of the License Agreement. In no event shall the U.S. Government acquire

greater than RESTRICTED/LIMITED RIGHTS. At a minimum, use, duplication, or disclosure by the U.S. Government is subject to restrictions as set forth in

FAR §52.227-14 Alternates I, II, and III (JUN 1987); FAR §52.227-19 (JUN 1987) and/or FAR §12.211/12.212 (Commercial Technical Data/Computer

Software); and DFARS §252.227-7015 (NOV 1995) (Technical Data) and/or DFARS §227.7202 (Computer Software), as applicable. Contractor/Manufacturer

is ESRI, 380 New York Street, Redlands, CA 92373-8100, USA.

ESRI, the ESRI globe logo, ArcGIS, ArcToolbox, ArcCatalog, ArcMap, ArcInfo, ArcSDE, GIS by ESRI, ArcView, ArcEditor, the ArcGIS logo, and www.esri.com

are trademarks, registered trademarks, or service marks of ESRI in the United States, the European Community, or certain other jurisdictions.

Other companies and products mentioned herein are trademarks or registered trademarks of their respective trademark owners.

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Contents 1 Introduction 1Who uses linear referencing? 2Tips on learning about linear referencing 8

2 Quick-start tutorial 9Exercise 1: Organizing your data in ArcCatalog 10Exercise 2: Creating and calibrating route data 12Exercise 3: Displaying and querying routes 18Exercise 4: Displaying and querying route events 25Exercise 5: Editing routes 33

3 Linear referencing 41The need for linear referencing 42Routes and measures 45Route locations and route events 46Linear referencing and topology 47

4 Creating route data 49Route data 50Creating route feature classes 57Creating routes from existing lines 64Calibrating routes with points 66Migrating route data to a geodatabase 69

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iv LINEAR REFERENCING IN ARCGIS

125 Displaying and querying routes and events 71

The route identifier field 72Querying route data 73Hatching 77Displaying hatches 85Manipulating the text on hatches 93Hatch styles 95Route measure anomalies 98Dynamic segmentation 99Adding route events 101

6 Editing routes 105Adding the Route Editing toolbar 106Creating routes from existing lines 107Calibrating routes with points 113Route measures 115Remeasuring routes 117

7 Creating and editing event data 121Creating and editing event data 122Creating event tables in ArcCatalog 128Overlaying events 132Aggregating events 135Transforming event measures 137Locating features along routes 140Editing event tables in ArcMap 142

Glossary 147

Index 157

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IN THIS CHAPTER

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Introduction 1• Who uses linear referencing?

• Tips on learning about linearreferencing

Many organizations collect data about linear features, such as highways, citystreets, railroads, rivers, and pipelines as well as water and sewer networks.In most geographic information systems (GIS), these features are modeledin two dimensions, using x,y coordinates. While these systems work well formaintaining features with static characteristics, these organizations haverealized that their linear features often have characteristics that are moredynamic in nature. To handle this, these organizations have developed one-dimensional linear referencing systems to model their data.

How these organizations store and utilize their linear referencing data variesnot only between the organizations themselves but also between thedepartments within the organizations. Because of this variance, there is aneed for flexible tools to create, display, query, analyze, and distributelinear referencing data.

ESRI® ArcGIS® software contains a series of easy-to-use tools, wizards, anddialog boxes that assist you in meeting your linear referencing needs. In thisbook, you will learn how to create, calibrate, edit, display, and query the dataused in linear referencing.

2 LINEAR REFERENCING IN ARCGIS

Most applications that use linear features can benefit from linear referencing. The following pages outline a few examples.

Highways and streets

Agencies that manage highways and streets use linear referencing in a variety of ways in their day-to-day operations. For example, linearreferencing is useful for assessing pavement conditions; maintaining, managing, and valuing assets (e.g., traffic signs and signals, guardrails, toll booths, and loop detectors); organizing bridge management information; and reviewing and coordinating construction projects.Linear referencing also helps facilitate the creation of a common database that traffic planners, traffic engineers, and public worksanalysts can use for cross-disciplinary decision support.

Who uses linear referencing?

Pavement conditions along the highways that serve Baltimore, Maryland

INTRODUCTION 3

Transit

Linear referencing is a key component in transit applications and facilitates such things as route planning and analysis; automaticvehicle location and tracking; bus stop and facility inventory; rail system facility management; track, power, communications, andsignal maintenance; accident reporting and analysis; demographic analysis and route restructuring; ridership analysis and reporting; andtransportation planning and modeling.

Corridor study showing the number of traffic accidents along an 18-mile stretch of the I-710 Freeway inLos Angeles County


Railways

Railways use linear referencing to manage key information for rail operations, maintenance, asset management, and decision supportsystems. Linear referencing makes it possible, for example, to select a line and track and identify milepost locations for bridges andother obstructions that would prevent various types of freight movement along the route. Further, dynamic segmentation can be used todisplay track characteristics as well as to view digital images of bridges and obstructions.

Analyzing rail clearances along the Hudson rail line in downstate New York

INTRODUCTION 5

Oil and gas exploration

The petroleum industry manages tremendous volumes of data used in geophysical exploration. Seismic surveys, or shotpoint data, areused to help understand the underlying geology in an area. The nature of seismic data is that it must be represented as both a linearobject—the seismic line—and a collection of point objects—the shotpoint. Both the seismic line and the individual shotpoints haveattributes, both must be maintained at the same time, and both are used in modeling applications. Linear referencing helps solve thisproblem.

Posting and labeling seismic lines and shotpoints in the Gulf of Mexico off the Louisiana coast


Pipelines

In the pipeline industry, linear referencing is often referred to as stationing. Stationing allows any point along a pipeline to be uniquelyidentified. As such, stationing is useful for collecting and storing information regarding pipeline facilities; both inline and physicalinspection histories; regulatory compliance information; risk assessment studies; work history events; and geographic information,such as environmentally sensitive areas, political boundaries (e.g., state and county), right-of-way boundaries, and various types ofcrossings.

Pipeline coating material types in rural Kansas

INTRODUCTION 7

Water resources

In hydrology applications, linear referencing is often called river addressing. River addressing allows objects, such as field monitoringstations, which collect information about water quality analysis, toxic release inventories, drinking water supplies, flow, and so on, to belocated along a river or stream system. Further, the measurement scheme used in river addressing allows for the measurement of flowdistance between any two points on a flow path.

Monitoring stations along the hydrology network of the Guadalupe River basin in southern Texas


If you’re new to GIS, take some time to familiarize yourself withArcGIS. The books Using ArcCatalog, Using ArcMap, Editing inArcMap, Building a Geodatabase, and Geoprocessing in ArcGIScontain tutorials to show you how to create, edit, manage, anddisplay GIS data.

Begin learning about linear referencing and dynamicsegmentation in Chapter 2, ‘Quick-start tutorial’, in this book. InChapter 2, you will learn how to create and calibrate route data,display and query route and event data, and edit route data.ArcGIS comes with the data used in this tutorial, so you canfollow along step by step at your computer. You can also read thetutorial without using your computer.

Finding answers to your questions

Like most people, your goal is to complete your tasks whileinvesting a minimum amount of time and effort in learning howto use software. You want intuitive, easy-to-use software thatgives you immediate results without having to read pages ofdocumentation. When you do have a question, however, you wantthe answer quickly so you can complete your task. That’s whatthis book is all about—getting you the answers you need whenyou need them.

This book describes how to accomplish linear referencing tasks.Although you can read this book from start to finish, you’ll likelyuse it more as a reference. When you want to know how to do aparticular task, such as identifying a route location, just look it upin the table of contents or index. What you’ll find is a concise,step-by-step description of how to complete the task. Somechapters also include detailed information that you can read ifyou want to learn more about the concepts behind the tasks. Youmay also refer to the glossary in this book if you come across anyunfamiliar GIS terms or need to refresh your memory.

Tips on learning about linear referencing

Getting help on your computer

In addition to this book, the ArcGIS Desktop Help system is avaluable resource for learning the software. To learn how to useHelp, see Using ArcMap.

Contacting ESRI

If you need to contact ESRI for technical support, refer to‘Contacting Technical Support’ in the ‘Getting more help’ sectionof the ArcGIS Desktop Help system. You can also visit ESRI onthe Web at www.esri.com and support.esri.com for moreinformation on linear referencing and ArcGIS.

ESRI education solutions

ESRI provides educational opportunities related to geographicinformation science, GIS applications, and technology. You canchoose among instructor-led courses, Web-based courses, andself-study workbooks to find educational solutions that fit yourlearning style. For more information, go to www.esri.com/education.

IN THIS CHAPTER

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Quick-start tutorial 2• Exercise 1: Organizing your data

in ArcCatalog

• Exercise 2: Creating andcalibrating route data

• Exercise 3: Displaying andquerying routes

• Exercise 4: Displaying andquerying route events

• Exercise 5: Editing routes

ArcGIS has the tools you need for linear referencing applications. The easiestway to start learning about linear referencing is to complete the exercises in thistutorial. Before you start, however, it is assumed you know the fundamentals ofArcGIS software. For more information, see Geoprocessing in ArcGIS, UsingArcCatalog, Using ArcMap, and Editing in ArcMap.

For this tutorial, imagine that you work in the GIS department of a highwayauthority responsible for the maintenance and safety of your region’s highways. Inthe exercises to follow, you will perform some of the linear referencing taskstypical to such a person. Specifically, you will use the linear referencing tools inArcToolbox™ to create and recalibrate route data. Next, you will learn how todisplay and query your newly created route data in ArcMap™. After that, you willdiscover how easy it is to display and query your route event data in ArcMap.Lastly, you will learn how to edit your route data in ArcMap.

The licenses required to complete each exercise vary from ArcView® toArcEditor™ to ArcInfo™. If you require a license different from ArcView, it will beindicated at the top of the page. Even if you don’t have the appropriate license,feel free to read through the exercises to familiarize yourself with the linearreferencing functionality in ArcGIS.

This tutorial includes five exercises, each of which takes five to 30 minutes tocomplete. The exercises build on one another, so it is assumed that you willcomplete them in order.

The study area for this tutorial is Pitt County, North Carolina. The data wascompiled from various sources and has been modified to suit the needs of theexercises. The reliability and suitability of the information, therefore, cannot beguaranteed.


Exercise 1: Organizing your data in ArcCatalog

The exercises in this chapter use the tutorial data distributedwith ArcGIS and work with an ArcView license. Some ofthese exercises require you to make changes to the data,therefore, you will need to have write access to the data.To be sure you have write access, you will begin thisexercise by making a working copy of theLinearReferencing tutorial folder.

Copying the data

1. Start ArcCatalog™ by either double-clicking a shortcutinstalled on your desktop or using the Programs list inyour Start menu.

2. Navigate to the LinearReferencing folder on the localdrive where the tutorial data is installed, for example,C:\arcgis\ArcTutor\LinearReferencing.

If the data was installed by your system administrator ina shared folder on the network, the path to the tutorialfolder includes the names of the computer and theconnection through which the folder is accessed, forexample,\\dataserver\public\ArcGIS\ArcTutor\LinearReferencing.

3. Right-click the Linear Referencing folder and clickCopy.

4. Navigate to the location where you would like to make acopy of this data, such as C:\.

5. Right-click this location and click Paste.

A new folder called Linear Referencing will be created atthis location.

6. Right-click this new folder and click Rename. Enter“MyLR” as the new folder name.

Connect directly to your tutorial data

In ArcCatalog, folder connections let you access specificdirectories on local disks or shared folders on the network.Further, database connections allow you to access thecontents of a database.

1. Click the Connect To Folder button on the Standardtoolbar.

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2. Navigate to and select your location of MyLR.

3. Click OK.

The new folder connection is now listed in the Catalog tree.You will now be able to access all of the data needed forthe remaining exercises in this tutorial via the newconnection.

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ArcInfo and ArcEditor

Exercise 2: Creating and calibrating route data

The first thing you will need for any linear referencingproject is accurate route data. In this exercise, you useArcToolbox tools to create and calibrate route data. Thefirst activity is to create a temporary layer representing onlythe line features that have route and measure informationstored as attribute values. Next, you will create a routefeature class by merging the input line features of thetemporary layer that share a common route identifier.Finally, you will recalibrate the newly created routes using apoint feature class storing route and measure information asattributes.

Creating a layer

Not every feature in the base_roads feature class has routeand measure information. Therefore, before any routes arecreated, you will want to isolate only those routes thatcontain this information. Creating routes using features thatdo not have this information would be pointless.

Creating a temporary layer allows you to do things, such asmake selections, without affecting the original data source.This layer will not appear in the ArcCatalog contents,because it is created in-memory and simply references thedata stored on disk. These layers can be used as inputs toother geoprocessing tools within your working session.Once you exit the application the in-memory layers will beremoved.

1. In ArcCatalog, show the ArcToolbox window by clickingthe Show/Hide ArcToolbox button on the Standardtoolbar.

You can click the top of the ArcToobox window and drag itaround the ArcCatalog window to dock it where you prefer.Also try double-clicking the top of the window to undock ordock it.

2. Expand the Data Management Tools toolbox to show itscontents.

3. Expand the Layers and Table Views toolset to show itscontents.

4. Right-click the Make Feature Layer tool and click Open.Alternatively you can double-click the Make FeatureLayer tool to open it.

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There are several ways to set the input feature class. Youcan drag a feature class from the ArcCatalog tree and dropit onto the text box, click the Browse button and navigate tothe feature class in the dialog box, or simply type the fullpathname to the feature class in the text box.

The tutorial instructions will simply ask you to type namesand paths into the appropriate text boxes. Feel free,however, to use any of the available techniques.

5. Type “C:\MyLR\PITT.mdb\PITT\base_roads” for thevalue of the Input Features parameter.

6. Type “measured_roads” for the value of the LayerName parameter.

7. Click the Expression button to open the Query Builderdialog box.

8. Type “[ROUTE1] <> 0” in the text box.

9. Click OK on the Query Builder dialog box.

10. Click OK on the Make Layer dialog box.

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The tool’s progress dialog box opens as the tool runs.

11. Click Close on the tool’s progress dialog box when theprocess is finished.



Creating route data

The Create Routes tool is used to specify the input linefeatures, the route identifier field, the method used to setthe route measures, and the output feature class. Note thatthe input features can be any supported format. Thisincludes coverage, shapefile, personal and enterprisegeodatabase, and computer-aided design (CAD) data.

1. Expand the Linear Referencing Tools toolset to show itscontents.

2. Right-click the Create Routes tool and click Open.

5. Type “C:\MyLR\PITT.mdb\PITT\routes” for the valueof the Output Route Feature Class parameter.

Next specify how the route measures will be obtained.There are three choices:

• Geometric lengths of the input features are used toaccumulate the measures.

• Values stored in a measure field are used to accumulatethe measures.

• Values stored in from- and to-measure fields are used toset the measures.

You will use the third method.

6. Click the Measure Source dropdown arrow and clickTWO_FIELDS.

This will enable both the From- and To-Measure Field inputfields.

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3. Click the dropdown arrow for the Input Line Featuresand click the measured_roads layer.

4. Click the Route Identifier Field dropdown arrow andclick ROUTE1. The values in the route identifier fielduniquely identify each route.

Next, you need to specify the name for the output featureclass. This feature class can be contained within the samegeodatabase as the input, or you can save it to anothergeodatabase or shapefile. If it is saved to a geodatabase itcan be contained within a feature dataset or on its own as afeature class. For this exercise you will be writing the newdata to the same feature dataset as the input.

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10. Expand Geodatabase Settings.

11. Click the Output M Domain dropdown arrow and clickAs Specified Below.

12. Type “-1000” for Min M and “10000” for Precision.

The precision setting will ensure that your routemeasures will be accurate to four decimal places.

13. Click OK to close each dialog box.



7. Click the From-Measure Field dropdown arrow and clickBEGMP1.

8. Click the To-Measure Field dropdown arrow and clickENDMP1.

When you are writing to an existing feature dataset (as youare here), the spatial reference settings of that dataset willbe applied to any new feature class. The exception to thisrule is the m domain. Feature classes within the samefeature dataset can have a different m domain. Thisaccounts for the fact that different route feature classesmight have different units of measure—for example, feet,meters, and miles. Whenever you create a route featureclass in an existing feature dataset, you should always setan appropriate m domain. The spatial domain for a featureclass or feature dataset cannot be changed. To learn moreabout the spatial reference, see later chapters in this bookor Building a Geodatabase.

9. Click Environments to access the spatial reference mdomain settings.

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Calibrating route data

Imagine that at some point in the future, the highwayauthority’s road maintenance crew acquired a distancemeasuring instrument (DMI) to accurately record mileageinformation along the highways. For a sample set ofhighways, the crew went out and captured mileageinformation approximately every 1/10 of a mile. The resultsof this effort were stored as points in a shapefile, where theroute and mileage information was stored as attributes.

In the next section of this tutorial, you will use the CalibrateRoutes tool to adjust the measures of the routes you justcreated to match those of the points in the shapefile. Theresult will be written to a new feature class.

The Calibrate Routes tool is used to specify the input routefeature class, the route identifier field, the input pointfeature class, the measure field, the methods used to set theroute measures, and the output feature class.

1. Right-click the Calibrate Routes tool in the ArcToolboxLinear Referencing toolset, and click Open.

2. Type “C:\MyLR\PITT.mdb\PITT\routes” for the valueof the Input Route Features parameter.

3. Click the Route Identifier Field dropdown arrow andclick ROUTE1. The values in the Route Identifier Fielduniquely identify each route.

4. Type “C:\MyLR\calibration_points.shp” for the value ofthe Input Point Features parameter.

5. Click the Point Identifier Field dropdown arrow and clickROUTE1. This is the common field, shared with theroute feature class.

6. Click the Measure Field dropdown arrow and clickMEASURE.

7. Type “C:\MyLR\PITT.mdb\PITT\routes_new” for thevalue of the Output Route Feature Class parameter.

A tolerance can be specified to limit how far a calibrationpoint can be from its route. Points outside the tolerance willnot be used by the calibration process.

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8. Click the Measure Calculation Method dropdown arrowand click DISTANCE.

9. Type “5” for the value of the Search Radius parameter.This is more than enough for the data that is being usedhere.

10. Click the Search Radius dropdown arrow and click Feet,to set the units to feet.

Again, you are writing to an existing feature dataset. Allspatial reference settings will be borrowed from that spatialreference. It is a good habit to set the m domain wheneverwriting route data to a geodatabase.

11. Click Environments to access the spatial reference mdomain settings.

12. Expand Geodatabase Settings.

13. Click the Output M Domain dropdown arrow and clickSame as Input.

You use the same m domain as the input route featureclass. Note, however, that it is always a good practice toset the m domain.

14. Click OK to close each dialog box.



In this exercise, you learned how to create a route featureclass by merging input line features that shared a commonidentifier and how to adjust the route measures usingmeasure information stored in a point shapefile. For moreinformation on creating and calibrating route data, seeChapter 4, ‘Creating route data’.

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Exercise 3: Displaying and querying routes

In this exercise, you will add the route data you created inExercise 2 to an existing map document and symbolize it.You will then

• Set the route identifier field.

• Add the Identify Route Locations tool to a toolbar.

• Identify route locations.

• Find route locations.

• Display route measure anomalies.

If you have not completed Exercise 2, open ArcCatalog.Within the Contents, delete PITT.mdb in your \MyLR folderand rename PITT_Results.mdb to PITT.mdb.

Opening an existing map document

To begin this exercise, you will start ArcMap and open anexisting document.

1. Double-click a shortcut installed on your desktop or usethe Programs list in your Start menu to start ArcMap.

2. In the Startup dialog box, choose to start using Anexisting map.

3. Double-click Browse for maps.

4. Click the Look in dropdown arrow in the Open dialogbox and navigate to the folder where you copied the datafor this tutorial (i.e., C:\MyLR).

5. Click Ex3.mxd to open the map in ArcMap.

6. Click Open.

This map contains the following layers in a data framecalled Pitt County:

calibration_points The points used in Exercise 2 to recalibrate the route measures

base_roads All of the roads in Pitt County

city boundaries The boundaries of the cities in PittCounty

county boundary Pitt County boundary

The map currently displays the city boundaries and countyboundary layers. Their check boxes are checked in thetable of contents. The calibration_points layer is checked,but scale suppression has been set. It will only be visiblewhen you zoom in to a scale beyond 1:25,000.

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7. Check the box next to the base_roads layer in the tableof contents.

You will now see all of the roads in Pitt County. Thisincludes roads not maintained by the highway authority. Theroads maintained by the highway authority were written tothe routes feature class.

Adding route data to your map

1. Click the Add Data button.

2. Click the Look in dropdown arrow and navigate to your\MyLR folder. Double-click PITT.mdb and double-clickthe PITT feature dataset.

3. Press the Ctrl key and select both the routes androutes_new feature classes.

4. Click Add.

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You will see the two new layers in the table of contents andalso displayed in the ArcMap window.

Changing the display symbol

The colors and symbols in which ArcMap chose to displaythe routes layer might make it difficult to see where theroute features are located. It is easy to change the colorsand symbols used to display features in ArcMap.

1. Click the line symbol in the table of contents for theroutes layer to display the Symbol Selector dialog box.

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2. Scroll down until you find a symbol you like and click it.

3. Click OK. Your routes layer will be displayed with thesymbol you chose.

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4. Repeat steps 1 through 3 for the routes_new layer.

You can also open the Symbol Selector dialog box by right-clicking the layer in the table of contents, clickingProperties, and clicking the Symbology tab. To simplychange the color of a symbol, right-click the symbol in thetable of contents to display the color palette, click any coloror More Colors. For more information on changing displaysymbols, see Using ArcMap.

You may have to click and drag the routes_new layerabove routes in the table of contents to be able to see it.

Setting the Route Identifier field

Whenever route data is added to a map, ArcMap knows toexpose some additional layer properties. One of theseproperties is the Route Identifier field. The contents of thisfield uniquely identify each route.

Setting the Route Identifier field is not required. Doing so,however, reduces the number of steps required to use manyof the ArcMap Linear Referencing dialog boxes, tools, andwizards.

1. Right-click the routes layer in the table of contents andclick Properties.

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2. Click the Routes tab.

3. Click the Route Identifier dropdown arrow and clickROUTE1.

4. Click OK.

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1. Click Tools and click Customize.

2. Click the Commands tab.

3. Click Linear Referencing in the Categories list.

4. Drag and drop the Identify Route Locations tool to thetoolbar of your choice, such as the Tools toolbar.

5. Click Close.

5. Repeat steps 1 through 4 for the routes_new layer.

Adding the Identify Route Locations tool

ArcMap gives you the ability to point to a route in a mapand find the route identifier along with the measure value atthat location. In this part of the exercise, you will use theIdentify Route Locations tool to inspect the measures onthe routes you created in Exercise 2.

The Identify Route Locations tool does not appear on anytoolbar by default. You will have to add it to one.

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Identifying route locations

In ArcMap, a bookmark is a saved map location. Abookmark containing some of the calibration points used inExercise 2 to recalibrate the routes has been created foryou.

1. Click View, point to Bookmarks, and click CalibrationPoints.

When ArcMap moves to the saved location, the calibrationpoints appear with labels that represent the measure valuesfor each point. The reason they appear when the bookmarkhas been used is because scale suppression was set on thelayer. For more information on scale suppression, see UsingArcMap.

2. Click the Identify Route Locations button.

3. Move the mouse pointer over one of the calibrationpoints and click. Route locations from both the routesand routes_new layers will be identified.

4. Click the route node for each of the route layers.

The numeric value listed for each of these nodescorresponds to the value stored in the Route Identifierfield, which you set in a previous section of thisexercise. Note that the measure value for the two routesdiffers. Note further that the measure value for theroutes_new layer corresponds closely to the measurevalue of the calibration point you clicked—the closer youare to a calibration point, the closer the measure will be.

5. Right-click the route node for one of the layers andexplore the context choices available to you.

6. Close the Identify Route Location Results window.

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7. Uncheck the check box for the calibration_points layerin the table of contents to make it not visible. It will notbe used any further in this exercise.

Finding route locations

In many linear referencing applications, you will discoverthat you will often need to find a location along a route. Forexample, you may need to find where an accident occurredalong a highway. On a paper map, it is hard to find a routelocation. This is because route measures are typically notshown. In ArcMap, finding a route location is made easy.

1. Click the Find button on the ArcMap Tools toolbar.

2. Click the Route Locations tab to open the Find dialogbox.

3. Click the Route Reference dropdown arrow and clickroutes_new.

Notice that the field listed in the Route Identifier dropdownarrow corresponds to the Route Identifier field you setpreviously in this exercise.

4. Click Load Routes.

5. Click the Route dropdown arrow and select 30000121.

This number is often a combination of many numeric fieldsand is meant to have no political, social, or economicmeaning, so that it will not change over time.

6. Type “5” in the Location text box.

7. Click Find.

8. Right-click the route location that was found and explorethe context choices available to you.

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9. Close the Find dialog box.

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Displaying route measure anomalies

In most linear referencing applications, route measurevalues are expected to follow a set of rules. For example,you might expect that route measures always increase overthe course of a route. ArcMap has the ability to show youwhere route measures do not adhere to the behavior youexpect. These are known as route measure anomalies.

1. Click the Full Extent button on the ArcMap Toolstoolbar.

2. Right-click the routes layer in the table of contents andclick Properties.


4. Check Show where measures do not increase.

5. Click the Line Symbol button and select a line symbolyou like. Do the same for the marker symbol.

6. Click OK.

Remember that the routes feature class was created fromthe base_roads feature class in Exercise 2. There are afew digitizing and attribute errors that caused the measureanomalies to exist in the routes feature class. Routemeasure anomalies can be fixed with ArcMap route editingtools. For more information on route editing tools, seeChapter 6, ‘Editing routes’.

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Exercise 4: Displaying and querying route events

In this exercise, you will create a new event table thatrepresents where injury accidents occurred along sectionsof poor-quality pavement. To do this, you will first use theAdd Route Events dialog box to display the accidentlocation and pavement quality event data on your map. Youwill then use the Select By Attributes dialog box to selectthe injury accidents and poor-quality pavement locations.You will use the Overlay Route Events tool to create a newevent table whose records represent where injury accidentsoccurred along poor-quality pavement. Finally, you will addthese events to the ArcMap display.



To begin this exercise, you will start ArcMap and open anexisting document.


2. Click File and click Open.

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3. Click the Look in dropdown arrow in the Open dialogbox and navigate to the location where you created the\MyLR folder.

4. Double-click Ex4.mxd. ArcMap opens the map.

This map contains the following layers in a data framecalled Pitt County:

routes_hwy Shapefile copy of routes_newfeature class you created inExercise 2

county boundary Pitt County boundary

accident Point event table storing accidentinformation

pavement Line event table storing pavementinformation

base_roads All of the roads in Pitt County

2


Displaying point events on your map

The accident table is a point event table. Point events occurat a precise point location along a route. In this section ofthe exercise, you will display the accident event data as alayer.

1. Click Tools and click Add Route Events.

2. Click the Route Reference dropdown arrow and clickroutes_hwy.


4. Click the Event Table dropdown arrow and clickaccident.


6. Click the Measure dropdown arrow and clickMEASURE.

7. Click OK.

A new layer—accident Events—has been added to yourmap.

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Displaying line events on your map

The pavement table is a line event table. Line events differfrom point events in that they have two measure fields thatdefine a portion of a route. The procedure for adding lineevents to your map is almost the same as adding pointevents.

1. Click Tools and click Add Route Events.

2. Click the Route Reference dropdown arrow and clickroutes_hwy.


4. Click the Event Table dropdown arrow and clickpavement.


6. Click Line Events.

7. Click the From-Measure dropdown arrow and clickBEGIN_MP.

8. Click the To-Measure dropdown arrow and clickEND_MP.

9. Click OK.

A new layer—pavement Events—has been added to yourmap.

You may have to use the zoom tool to zoom in on the mapto see the pavement Events, or you could click and movethe pavement Events layer to the top of the layer list in thetable of contents.

1


Querying events

Layers based on an event table can be queried in manyways. They can be identified by clicking them, they can beselected by dragging a box or clicking them on the map,they can be selected by clicking them in an attribute table,and they can be selected using a Structured QueryLanguage (SQL) expression. You will use the Select ByAttributes dialog box to input expressions to select the eventrecords needed for this exercise. Specifically, you willselect injury accidents and poor quality pavement.

1. Click Selection and click Select By Attributes.

2. Click the Layer dropdown arrow and click accidentEvents.

3. Scroll down and double-click NUM_INJURY in theFields list.

4. Click the greater than operator (>).

5. Click Get Unique Values.

6. Double-click 0 in the Unique Values list.

“NUM_INJURY” > 0 should be the expressionappearing in the text box.

7. Click Apply.

You will see a number of the features in the accidentEvents layer selected in the ArcMap display window.

8. Click the Layer dropdown arrow and click pavementEvents in the Select By Attributes dialog box.

9. Type the following in the text box: “RATING” < 50

10. Click Apply.

11. Click Close.

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Now both the accident and pavement events are selectedon your map. To see this more clearly, you may want touncheck and check the accident Events and pavementEvents layers in the table of contents.

In the next section of this exercise, you will use the OverlayRoute Events tool in ArcToolbox to intersect the two eventlayers. The result will be a table that contains the injuryaccidents that happened on poor-quality pavement. Allattributes from both inputs are maintained. First, however,you need to be sure that your geoprocessing results areautomatically added to your display.

Setting geoprocessing results to displayautomatically

1. Click Tools and click Options.

2. Click the Geoprocessing tab.

3. Check Add results of geoprocessing operations to thedisplay.

4. Click OK.

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Intersecting event layers

1. Click the Show/Hide ArcToolbox button.

This opens the ArcToolbox window. You can dock andundock this window or move this window around theArcMap window.

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2. Expand the Linear Referencing Tools.

3. Right-click the Overlay Route Events tool and clickOpen.

4. Click the Input Event Table dropdown arrow and clickthe accident Events layer.

NOTE: Because you selected an event layer, the RouteIdentifier Field, Event Type, and Measure Fields were setautomatically. If you had selected an event table, you wouldbe responsible for setting these parameters.

5. Click the Overlay Event Table dropdown arrow and clickthe pavement Events layer.

6. Click the Type of Overlay dropdown arrow and clickINTERSECT. This will allow you to find the intersectingevent layers.

7. Type “C:\MyLR\AccPav.dbf ” for the value of theOutput Event Table parameter.

You’ll keep the remaining defaults.

8. Click OK.

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4. Click the Route Identifier Field dropdown arrow andclick ROUTE1.

5. Click the Input Event Table dropdown arrow and clickAccPav.

6. Click the Route Identifier Field dropdown arrow for theevent table and click ROUTE1.

7. Click OK.

Q

10. The AccPav.dbf table is added to the ArcMap session.If you cannot see it in the table of contents, click theSource tab.

Displaying the intersected event results

At the beginning of this exercise, you used the Add RouteEvents dialog box (from the Main menu) to display theaccident and pavement condition information as layers inyour map. Another way to do this is to use the Make RouteEvent Layer tool (from ArcToolbox). When called fromArcCatalog, this tool creates a temporary, in-memory layersimilar to the one you created in Exercise 2. Whenexecuted in ArcMap, the in-memory layer is added to thedisplay.

1. Expand the Linear Referencing Tools in ArcToolbox.

2. Right-click the Make Route Event Layer tool and clickOpen.

3. Click the Input Route Features dropdown arrow andclick the routes_hwy layer.

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The AccPav Events layer is added to the table of contents.

8. Uncheck the accident Events and pavement Eventslayers in the table of contents.

You will now see only the injury events that occurred alongpoor quality pavement. Each of these new events has allthe attributes from both the accident and pavement tables.

For more information on the display and query of events orthe spatial analysis of events, see Chapter 5, ‘Displayingand querying routes and events’, and Chapter 7, ‘Creatingand editing event data’.



Exercise 5: Editing routes

There are a number of tools in ArcMap that make theinteractive creation and editing of route measures easy. Inthis exercise, you will create a new route from a selectedset of linear features and set its identifier. You will thenconvert the measures of this newly created route from feetto miles. Last, you will recalibrate the route using knownmeasure values at specific locations on your map.



In order to use this exercise, you must start ArcMap.


2. Click File and click Open.

3. Click the Look in dropdown arrow in the Open dialogbox and navigate to the folder where you installed thedata for this tutorial.

4. Double-click Ex5.mxd. ArcMap opens the map.

Adding route data to your map

You will use one of the route feature classes you created inExercise 2 to complete this exercise.

1. Click the Add Data button.

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2. Click the Look in dropdown arrow and navigate to your\MyLR folder. Double-click PITT.mdb and double-clickthe PITT feature dataset.

3. Click the routes_new feature class.

4. Click Add.

Adding the toolbars, editing, and setting the targetfeature class

The toolbars necessary to complete this exercise might notbe visible.

1. Click the Editor Toolbar button to add the Editor toolbarto ArcMap.

2. Click the Editor menu, point to More Editing Tools, andclick Route Editing.

3. Click the Editor menu and click Start Editing.

4. Click the Target dropdown arrow on the Editor toolbar,and click routes_new.

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Making a route from selected features

The highway authority has been informed that it will now beresponsible for maintaining a road that it previously had notbeen maintaining. It is necessary, therefore, to select theappropriate features from the base_roads feature class andmake a route in the routes_new feature class out of them.

The Make Route command creates a new route in thetarget feature class by merging a selected set of linefeatures and setting the measure values. The selected linefeatures do not need to be from the target feature class.

1. Click Selection and click Select By Attributes.

2. Click the Layer dropdown arrow and click base_roads.

3. Type the following in the text box:[FENAME] = ‘Cornerstone Row’

If you’re clicking in the field boxes to build the expression,you may need to click Complete List, under Unique samplevalues.

4. Click Apply.

5. Click Close.

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Nine features from the base_roads feature class are nowselected.



8. Click Selected to show only the selected records. Youcan also see the total number of selected records shownalong the bottom of this window.

9. Close the Attributes table.

10. Click the Make Route button on the Route Editingtoolbar.

6. Right-click the base_roads layer in the table of contents,point to Selection, and click Zoom To Selected Features.

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7. Right-click the base_roads feature class layer and clickOpen Attribute Table.

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The new route will flash when it is being created. Duringthe route creation process, the selected lines will bedeselected, and the new route will be selected. This is soyou can set the new route’s attributes.

Setting the Route Identifier

Because the newly created route is selected, you can nowset the route identifier. The route identifier uniquelyidentifies each route.

1. Click the Attributes button on the Editor toolbar.

2. Click the ROUTE1 Value and type “40001777”.

3. Press Enter on your keyboard.

4. Close the Attributes dialog box.

11. Click the Start Point button.

The Make Route dialog box changes and lets you know youneed to pick a route starting point.

12. Click the map near the upper-right corner of theselected set of features. This is where the output route’smeasures will begin.

The program tries to assist you by circling the endpoint itwill select. As you move your mouse along the route, thispoint can change. This is useful because you do not need toselect the exact spot on the route; just click on the displaywhen the correct location is circled.

13. Click Make Route on the Make Route dialog box.

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Converting route measure units

When you created the new route, you accepted the defaultmethod for setting the route measures. This methodaccumulates the geometric length of the input line featuresand uses the length as the measure. Because the coordinatesystem of the feature class is State Plane Feet, themeasures on the new route are in feet. However, themeasures on all other routes in the feature class are inmiles.

1. The newly created route should still be selected. If it isnot, select it.

2. Click the Task dropdown arrow on the Editor toolbar andclick Modify Feature.

The selected feature will now be loaded into the editsketch.

3. Click the Sketch Properties button.

Note the size of the measure values (in column M).

4. Close the Edit Sketch Properties dialog box.

5. Right-click anywhere over the edit sketch (you knowyou are over the line when the mouse pointer changes),point to Route Measure Editing, and click Apply Factor.

6. Type “0.00018939” in the Factor text box and pressEnter on the keyboard. This converts feet to miles.

At this point, you have only made changes to the editsketch, not the route feature.

7. Press F2 to finish the edit sketch. Alternately, right-clickanywhere over the edit sketch and click Finish Sketch.

Your route measures are now in miles. You can verify thisby double-clicking the selected route to bring it into the editsketch, right-clicking anywhere over the sketch, andclicking Properties. Note that this is an alternate way toperform Steps 2 and 3.

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Recalibrating a route

So far in this exercise, you have created a route andtransformed its measures from feet to miles. Imagine thatat some point the maintenance crew went out into the fieldand recorded the actual mileage for this new route. Themileage was captured every time the new route intersectedwith another route from the same feature class. In thissection of the exercise, you will recalibrate the newlycreated route based on this mileage information.

1. The newly created route should still be selected. If it isnot, select it.

2. Click the Editor menu and click Snapping.

This opens the Snapping Environment window, which is adockable window.

3. Check the End check box next to the routes_new andbase_roads layers.

4. Close the Snapping Environment dialog box. It will notbe used again in this exercise.

With the snapping environment set, you will be able tocreate calibration points that are snapped to the end vertexof the features in the routes_new layer, thereby ensuringaccuracy of the route measures at the calibration points.Setting the snap environment, however, is not necessary forthe Calibrate Route command to work.

5. Click the Task dropdown arrow and click CalibrateRoute Feature.

6. Click the Calibrate Route button on the Route Editingtoolbar.

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The Calibrate Route dialog box is now on the screen, but itis empty. Your next task is to digitize the calibration points.

7. With the Calibrate Route dialog box open, click theSketch tool on the Editor toolbar.

8. Click along the route at nine different places to createthe calibration points. The locations of the calibrationpoints are indicated in the graphic below.

9. Enter the New M values (see values in graphic below)for each calibration point by clicking each value in thecolumn and typing the new value.

10. Click Calibrate Route.

Saving your edits

Once you have completed the steps in this exercise, youcan choose to save or discard your edits by stopping the editsession.

1. Click the Editor menu and click Stop Editing.

2. Click Yes to save your edits.

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In this exercise, you first learned how to create a routefrom a selected set of line features. Next, you convertedthe route measures from feet to miles. Last, you learnedhow to recalibrate a route using calibration points youdigitized on the map.

For more details about the route editing tools outlined hereor for information on tools not discussed in this chapter, seeChapter 6, ‘Editing routes’.

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IN THIS CHAPTER

41

Linear referencing 3• The need for linear referencing

• Routes and measures

• Route locations and route events

• Linear referencing and topology

Highways, city streets, railroads, rivers, pipelines, and water and sewernetworks are all examples of linear features. Linear features typically haveonly one set of attributes. Linear referencing, however, provides you with anintuitive way to associate multiple sets of attributes to portions of linearfeatures. With linear referencing, your ability to understand, maintain, andanalyze linear features is greatly improved.

This chapter outlines the way linear features are modeled in ArcGIS. It thenintroduces you to what linear referencing is, explains why it is needed, andoutlines the concepts necessary to develop linear referencing applications.Once you understand the concepts introduced in this chapter, you can refer tolater chapters in this book to use the wide range of linear referencingfunctionality in ArcGIS.


Geographic data is modeled in a number of ways: as a collectionof features in vector format, as a grid of cells with spectral orattribute data in raster format, or as a set of triangulated pointsmodeling a surface in triangulated irregular network (TIN) format.

Data having a discrete location with a defined shape andboundary is modeled using the vector format. In this format, datais represented by features, which are stored in feature classes.Every feature has a geometry associated with it. This geometry isstored in a special field typically called shape. A feature can haveone of these types of geometries: point, multipoint, polyline, orpolygon. Each geometry is composed of two-dimensional (x,y) orthree-dimensional (x,y,z) geographic coordinates.

The need for linear referencing

The vector format works well for modeling features with staticcharacteristics, such as parcel boundaries, water bodies, and soilcharacteristics. Some applications, however, require the ability tomodel the relative location along various linear features, such ashighways, city streets, railroads, rivers, pipelines, and water andsewer networks.

Because of this need, one-dimensional measuring systems, suchas river mile and route milepost, have been devised. Thesesystems simplify the recording of data by using a relativeposition along an already existing linear feature. That is, locationis given in terms of a known linear feature and a position, ormeasure, along it. For example, route I-10, mile 23.2, uniquelyidentifies a position in geographic space without having toexpress it in x,y terms.

When data is linearly referenced, multiple sets of attributes canbe associated with any portion of an existing linear feature,independent of its beginning and end. These attributes can bedisplayed, queried, edited, and analyzed without affecting theunderlying linear feature’s geometry.

The need to visually represent features on a map whosecoordinates are not geographic but are recorded as a relativedistance along another linear feature led to the development ofdynamic segmentation. Dynamic segmentation is the process ofdisplaying linearly referenced features on a map. For moreinformation on dynamic segmentation, see Chapter 5, ‘Displayingand querying routes and events’.

In the vector format, geographic data is stored as a feature that has ageometry type of point, multipoint, polyline, or polygon.

Y

X

(1,2)

(3,3)

(5,1)

(7,5)

(8,2)

(9,5) (12,5)

(12,2)

(11,3)

LINEAR REFERENCING 43

Storing features as relative locations

Locating a spatial feature along another linear feature wouldtypically be done using a planar (two-dimensional) referencingsystem of x,y coordinates.

This works well in some applications. In others, however,locations along linear features are referred to in terms of theirdistance from a known point. For example, it makes much moresense to record the location of an accident as occurring at“12 miles from the beginning of the interstate” rather than at“1659060.25, 1525238.97”.

To determine a location along a linear feature, a system ofmeasurement is required. When a measurement system is storedwith a linear feature, any location along that linear feature can beexpressed in terms of the measure values.

In addition to making data more intuitive, storing data as arelative location along a linear feature has the added benefit ofensuring that spatial phenomena you know to be along a linearfeature is mapped as such. For example, in the absence of anaccurate basemap, locating accidents using x,y coordinates mayend up displaying accidents that do not fall along the roadnetwork. This cannot happen if the accidents are stored asmeasurements along the linear features of the road network.

Segmented data

The vector model of data storage dictates that you must split alinear feature wherever its attribute values change. Certain linearfeatures, however, have attributes that change frequently. Thepavement condition of a road, for example, changes as pavementdeteriorates and is subsequently repaired. To accurately reflectthe changes in pavement condition, you will have to split somefeatures and merge others.

Segmenting the linear features becomes more problematic whenyou need to store other attributes, such as traffic volumes, laneinformation, surface material, speed limits, and accidentlocations. Every time these attributes change, the road will needto be further subdivided. With all the required segmenting, it isevident that the linear features will be so subdivided that the datawill be difficult, if not impossible, to maintain.

To attach attributes describing pavement quality, it is necessary to split alinear feature at several locations to reflect changes in data. Over time,pavement quality changes, requiring features to be split or merged.

02/2002 Fair Good Poor Good

10 20 30 40

08/2001 Fair Good Poor Good

Locating accidents using x,y coordinatesX

Y

(x,y)(x,y)

(x,y)

Locating accidents using measure values

1222

0 10

20 30

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ArcGIS uses route event tables to store linearly referencedattributes. Event rows are composed of a route identifier, measurevalues indicating a location, and one or more attributes describingthe location. For more information on route event tables, see‘Route locations and route events’ in this chapter.

Because events simply reference measure locations along linearfeatures, they are edited and maintained independently of thelinear features. For more information on maintaining event data,see Chapter 7, ‘Creating and editing event data’.

Speed 45 35 45 55

Asphalt Concrete AsphaltMaterial

2 4Lanes

10 20 30 40

Accidents

Quality Fair Good Poor Good

Storing multiple sets of attributes for one feature is made possible usinglinear referencing.


Routes and measures

When linearly referenced features in ArcGIS are referred to, theterms routes and route events are used. A route is any linearfeature, such as a city street, highway, river, or pipe, that has aunique identifier and a measurement system. This measurementsystem defines discrete locations along the linear feature. Formore information on route events, see ‘Route locations and routeevents’ in this chapter.

A collection of routes with a common system of measurement canbe stored in a single feature class—such as a set of all highwayroutes in a county. In a geodatabase, many feature classescontaining routes can be stored in a single feature dataset. Forexample, a state’s department of transportation (DOT) mightmaintain a feature dataset with feature classes for milepost routes,reference marker routes, and so on.

Linear features and, therefore, routes are stored in a feature classwhose geometry type is a polyline. A polyline is an orderedcollection of paths that can be connected or disjointed. Polylinesare used to represent such things as roads, rivers, and contours.

A feature dataset can have multiple feature classes that store routes.

Polylines can have a measurement system stored with theirgeometry. Instead of being a collection of segments with x,ycoordinates, a measured polyline’s segments have x,y and m(measure) or x,y,z and m values. When a measure value isunknown, it is listed as NaN (not a number).

It is important to note that although many applications usemeasures to represent increasing distances along a linear feature,measure values can arbitrarily increase, remain constant, ordecrease.

Measure values are independent of the coordinate system of afeature class. That is, the measure values are not required to be inthe same units as the feature class’s x,y coordinates. For example,features stored in a feature class whose coordinate system isUniversal Transverse Mercator (UTM) meters might havemeasure values stored in feet or miles.

Polylines can have a measurement system stored with their geometry.Measures can be unknown (NaN).

010

20

300

NaN

NaN

30

A polyline is an ordered collection of paths that can be connected ordisjointed.

Polyline with one path Polyline with multiple,connected paths

Polyline with multiple,disjointed paths

A route is a linear feature with a unique identifier and a measurementsystem.


Route locations and route events

A route location describes a discrete location along a route(point) or a portion of a route (line). A point route location usesonly a single measure value to describe a discrete location alonga route. An example of a point route location is “mile 3.2 on theI-91.” A line route location uses both a from- and a to-measurevalue to describe a portion of a route. “Mile 2 to mile 4 onthe I-91” is an example of a linear route location.

When route locations—and their associated attributes—arestored in a table, they are known as route events or simply events.Events are organized into tables based on a common theme. Forexample, five event tables containing information on speed limits,year of resurfacing, present condition, signs, and accidents canreference highway routes.

Route event tables

Because there are two types of route locations, there are twotypes of route event tables: point and line.

A route event table, at a minimum, consists of two fields: a routeidentifier and a measure location. The route identifier field is anumeric or character value used to identify the route to which anevent belongs. A measure location is either one or two fields thatdescribe the positions along the route at which the event occurs.These values can be defined as any numeric item.

An event table can be any type of table that ArcGIS supports.This includes INFO™, dBASE®, geodatabase tables, delimitedtext files, and database management system (DBMS) tablesaccessed via an Object Linking and Embedding Database (OLEDB) connection.

Point events

Point events occur at a precise point location along a route.Accident locations along highways, signals along rail lines, busstops along bus routes, and pumping stations along pipelines areall examples of point events. Point events use a single measurevalue to describe their location.

Line events

Line events describe portions of routes. Pavement quality, salmonspawning grounds, bus fares, pipe widths, and traffic volumes areall examples of line events. Line events use two measure values todescribe their location.

Events are located along a route using their route location information.Here, point events representing flow gauges along river reaches areshown.

A12

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A3

B1

B2

GAUGE_ID

B456

B456

A123

A123

A123

REACH MP

A2

GAUGES

Route identifier

Measure location

5 13153017

5225

SALMONSTEELHEAD

SALMONSTEELHEAD

SPECIESTMP

B456A123A123A123

REACH FMP

25

HABITAT

A12

3

B45

6

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55

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37

Route identifier

Measure location

Events are located along a route using their route location information.Here, line events representing fish habitats along river reaches are shown.


Within an organization, there may be many departments that useroute event data. Each department will collect event data usingthe route measurement system that best suits its needs. Within astate DOT, for example, the safety department might collectaccident location events using a reference marker system ofmeasurement, while the maintenance department might collectpavement quality information using a milepost system ofmeasurement. Each system is known as a linear referencingmethod.

A route in ArcGIS can only store one system of measurement. Inmany organizations, therefore, there is a need to maintain multipleroute feature classes—one for each linear referencing method.The ability to manage these feature classes in an integratedfashion is critical.

Linear referencing and topology

In GIS technology, topology is the model used to describe howfeatures share geometry. It is also the mechanism for establishingand maintaining topological relationships between features andfeature classes. ArcGIS implements topology through a set ofvalidation rules that define how features share geographic spaceand a set of editing tools that work with features that sharegeometry in an integrated fashion.

By defining a topology, organizations can achieve the dataintegration between route feature classes they require. For moreinformation on topology, see Building a Geodatabase andEditing in ArcMap.

A topology facilitates the use of multiple linear referencing methods.

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Creating route data 4• Route data

• Creating route feature classes

• Creating routes from existing lines

• Calibrating routes with points

• Migrating route data to a geodata-base

Before embarking on any linear referencing project, you will need routedata. This data may not exist, may exist but without the appropriate measuresystem defined, or may exist in a format you do not wish to use.

ArcGIS supports routes in three formats: coverage, shapefile, andgeodatabase. ArcCatalog and ArcToolbox provide you with the toolsnecessary to create, calibrate, and migrate route data from one supportedformat to another.

In this chapter, you will learn how to:

• Create new route feature classes.

• Create route feature classes from existing lines.

• Calibrate routes using points.

• Migrate routes from one format to another.



Route data

A route is a linear feature that has a unique identifier andmeasurement system stored with it. Routes can be stored incoverages, shapefiles, personal geodatabases, and ArcSDE®

geodatabases.

ArcCatalog and ArcToolbox contain tools for creating route datain shapefiles and geodatabases. In addition to the ability to createempty route feature classes for later digitizing or importing, thereare tools for creating routes by merging existing line features,calibrating route data with points, and migrating route data fromone format to another. When a route feature class is stored in ageodatabase, there are special storage considerations. Some ofthese are general geodatabase considerations that can be readabout in Building a Geodatabase. Others are particular to linearreferencing applications and will be explained further in thissection.

There are tools for creating routes in coverages, but they will notbe discussed in this chapter. ArcInfo Workstation remains thebest place to create coverage route data. For more information oncreating coverage route data, see the ArcInfo Workstation onlineHelp.

Merging linear features to create routes

It is possible to create routes by merging linear features thatshare a common identifier. There are two scenarios for how theroute measures will be set:

• Measure values for the input features are not known.

• Measure values for the input features are known.

Measure values are not known

When route measure values are not known, they can begenerated either by accumulating the digitized length or byaccumulating a numeric attribute value of the input features. Ifyou choose to use digitized length, the units of the output routemeasures will be the same as the output coordinate system (e.g.,feet or meters). If you choose to use a numeric attribute, theoutput route measures can be in any units you want.

When routes are created in this manner, you control the directionmeasures are assigned to the routes by specifying the coordinatepriority of the starting measure. The coordinate priority can beupper left, upper right, lower left, or lower right. These options aredetermined by placing the minimum bounding rectangle aroundthe input features that are going to be merged to create one route.

Routes can be stored in coverages, shapefiles, and geodatabase featureclasses.

geodatabase

coverage

shapefile

CREATING ROUTE DATA 51


Routes with multiple, disjointed parts are supported. A routerepresenting a road, for example, might have the same name oneither side of a river. For situations like this, you can choose toignore spatial gaps between parts when creating routes. If youchoose to ignore spatial gaps, route measures will be continuouswhen a disjointed route is created. If you want the spatial gapincorporated in the measures, the gap distance is the straight-linedistance between the endpoints of the parts. The units of the gapwill be that of the output coordinate system, which may or maynot be the same as the measure units.

Polyline 1PolylinePolylinePolyline

11

1.10.60.60.9

MILESRKEY

3210

OID Shape

1

OID = 01

2

PolylineM 1RKEY

0OID Shape

0

1.11.7

3.2

3

1.7

2.3

0

1.12.1

3.6

1.7

2.7

When creating disjointed routes, you can choose to have the measures becontinuous or discontinuous. In this example, the starting priority is lowerleft.

Polyline 1PolylinePolyline 1

01.12.3

1.12.33.2

TO_MFR_MRKEY

210

OID Shape

1

OID = 0 1 2

PolylineM 1RKEY

0OID Shape

0

1.1

2.3

3.2

Measure values are obtained by using the values in the FR_M and TO_Mfields. Note that the digitized direction of the input features determines thedirection of the output route.

Polyline 1PolylinePolyline 1

1.11.20.9

MILESRKEY

210

OID Shape

1

OID = 0 1 2

PolylineM 1RKEY

0OID Shape

0

1.1

2.3

3.2

Measure values are obtained by accumulating the values in the MILESfield. Note that the digitized direction of the input features does not matterbecause a starting priority is given. In this example, the starting priority islower left.

Measure values are known

When measure information already exists as attributes of theinput linear features, it is possible to create routes that inherit thismeasure information. For example, two fields may exist that storefrom- and to-mile information.

When using this method, it is important to orient each input linearfeature in the direction of increasing measure to prevent routesthat have measures that do not always increase.



The calibration process creates a new vertex for every point within thespecified tolerance. The measure at each new vertex will correspond tothe point’s measure value. You control whether the remaining vertices willhave their measure interpolated or extrapolated.

Tolerance

0

9

22

32

40

?

?

?

?

?

5

15

30

34

5 1530

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Calibrating route measures using points

When route measures are inaccurate, events will not be locatedproperly. A route representing a highway, for example, might be10.5 miles long. A bend in the highway might have its measurevalue set to 6.1 miles. In reality, however, the bend in the highwayoccurs at mile 6.5. Events on this route, especially near the bend,will be located incorrectly.

It is possible to adjust route measures to correspond with knownmeasure locations using a procedure called calibration.Calibration adjusts route measures by reading measureinformation stored as an attribute in a point feature class. Eachpoint falls on the particular route it calibrates or within a givenradius. Many points may be used to calibrate a single route.

During the calibration process, a new vertex is created where thecalibration points intersect the route. The measure value on thesenew vertices corresponds to the measure value stored as a pointattribute. The measure values on other preexisting route verticescan be interpolated and/or extrapolated.

Both whole and partial routes can be calibrated. You can chooseto interpolate between the input points, extrapolate before theinput points, extrapolate after the input points, or use anycombination of these three methods.

In order for the measure value on a vertex to be interpolated orextrapolated, a calibration ratio is needed. There are two ways thisratio can be determined. The first method uses the shortest pathdistance between the input points.

1.88

9.69

19.62

31.75

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Measure value at v1 is extrapolated as follows: - distance (d1) between p1 and p2 is 14.31 - measure distance between p1 and p2 is 15-5 = 10 - calibration ratio is 14.31/10 = 1.431 - distance (d2) between p1 and v1 is 4.47

The measure value at v2 is interpolated as follows: - distance (d1) between p1 and p2 is 14.31 - measure distance between p1 and p2 is 15-5 = 10 - calibration ratio is 14.31/10 = 1.431 - distance (d3) between p1 and v2 is 6.71



The measure value at v5 is extrapolated as follows: - distance (d6) between p3 and p4 is 7.16 - measure distance between p3 and p4 is 34-30 = 4 - calibration ratio is 7.16/4 = 1.79 - distance (d8) between p4 and v5 is 7.16

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4.47/1.431 = 3.125-3.12 = 1.88

6.71/1.431 = 4.695+4.69 = 9.69

3.58/0.775 = 4.6215+4.62 = 19.62

3.13/1.79 = 1.7530+1.75 = 31.75

7.16/1.79 = 434+4 = 38

The calibration ratio can be determined using the shortest path distancebetween the input points.



The second method uses the existing measure distance betweenthe input points. This second method is useful when the lengthto measure ratio on the input route is not consistent and you areusing the calibration process to fine-tune a route’s measures.

When calibrating disjointed routes, you may choose to ignore thedistance of the spatial gap between the parts. If you choose toignore spatial gaps, route measures will be continuous. If youwant the spatial gap incorporated in the measures, the gapdistance is the straight-line distance between the endpoints ofthe parts. The units of the gap will be that of the outputcoordinate system, which may or may not be the same as themeasure units. Ignoring spatial gaps is only a valid choice whenusing the shortest path distance method of calibration.

The measure value at v1 is extropolated as follows: - old measure distance (d1) between p1 and p2 is 17.84-3.6 = 14.24 - new measure distance between p1 and p2 is 15-5 = 10 - calibration ratio is 14.24/10 = 1.424 - old measure distance (d2) between p1 and v1 is 3.6-0 = 3.6

The measure value at v2 is interpolated as follows: - old measure distance (d1) between p1 and p2 is 17.84-3.6 = 14.24 - new measure distance between p1 and p2 is 15-5 = 10 - calibration ratio is 14.24/10 = 1.424 - old measure distance (d3) between p1 and v2 is 9-3.6 = 5.4



The measure value at v5 is extropolated as follows: - old measure distance (d6) between p3 and p4 is 34.88-29.2 = 5.68 - new measure distance between p3 and p4 is 34-30 = 4 - calibration ratio is 5.68/4 = 1.42 - old measure distance (d8) between p4 and v5 is 40-34.88 = 5.12

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3.6/1.424 = 2.535-2.53 = 2.47

5.4/1.424 = 3.795+3.79 = 8.79

4.16/0.757 = 5.4915+5.49 = 20.49

2.8/1.42 = 1.9730+1.97 = 31.97

5.12/1.42 = 3.6134+3.61 = 37.61

The calibration ratio can be determined using the measure distancebetween the input points.


Special considerations for geodatabases

When you create a new standalone feature class or a featureclass in a new feature dataset, you must specify a spatialreference. The spatial reference for a feature class contains itscoordinate system—for example, geographic, UTM, and StatePlane—and the spatial domains—x,y,z, and m. For moreinformation on spatial references, see Building a Geodatabase.

You need to choose appropriate x,y,m, and perhaps z domainswhen creating route feature classes because they describe themaximum extent to which data can grow. For example, if you createa feature class with a minimum m-value of 0 and a precision of1,000, none of the routes in the feature class will be able to havemeasures that are less than 0. Furthermore, all route measures willbe accurate to three decimal places (a precision of 1,000 impliesaccuracy to three decimal places). Similar considerations apply tothe x,y, and z domains.

All feature classes in a feature dataset share a common spatialreference. This means that the domains are shared as well. Theexception to the rule is the m domain. Feature classes within thesame feature dataset can have a different m domain. This is toaccount for the fact that different route feature classes mighthave different units of measure—for example, feet, meters, andmiles. Whenever you create a route feature class in an existingfeature dataset, you should always set an appropriate m domain.

Choosing an appropriate m domain

However route data is created, one important goal is to preservemeasure accuracy. When data is stored in a geodatabase, allnumeric values are converted to integers. Because of this,converting data to and from integer space can sacrifice measureaccuracy if inappropriate m domain values are used.

To determine an appropriate m domain, you need to know boththe route storage units and the route measure units. The routestorage units reflect how accurately the route data was collected.For example, route measure data may be accurate to the foot,meter, or even decimeter level.

The route measure units refer to the units in which routelocations are reported. For example, they may be feet, meters,miles, and so on. Route measure units have nothing to do withhow accurately the route’s data was collected and stored.

Precision is the multiplier that scales measure units into storageunits. The lowest precision value you should use is the routemeasure units divided by the storage units. For example, if theroute measure units are kilometers and there is meter-levelaccuracy, the lowest precision value you should use is 1,000. Thisis because there are 1,000 meters in a kilometer, and 1/0.001 equals1,000. Further, if the route measure units are miles and there isaccuracy to the foot, the lowest precision you should use is 5,280(there are 5,280 feet per mile).

Suppose you have a route feature class in which the routemeasure units are kilometer and the route storage units areaccurate to the meter level. Further suppose that this routefeature class has an m domain in which the measure minimumis -1,000 and the measure precision is 100, which is incorrect. If anew route is created in this feature class and its measure valuesare set to range between 0 and 1,324.526, the following diagramillustrates that the accuracy of the route’s measures is notmaintained when the route is stored and subsequently retrievedfrom the geodatabase. Note that the same process happens forevery measure value on the route.


If the route feature class has an appropriate m precision of 1,000,the measure accuracy of the route is maintained on a round-trip tothe geodatabase.

It is often a good idea to use a precision that is greater than thecalculated value to allow for the future storage of more accuratedata. In most cases this is not a problem, but be aware that thereis a trade-off between precision and the range of measure inwhich values can be stored. The higher the precision value that isused, the smaller the range of measure values that routes canhave.

Grid size

Another consideration regarding geodatabase feature classes isthe grid size of the spatial index. The spatial index is used toquickly locate features that match the criteria of a spatial search.

For most data, only a single grid size is required. Because featuresize is an important factor in determining an optimum grid size,data that contains features of very different sizes may requireadditional grid sizes so larger features can be queried faster.Feature classes in ArcSDE geodatabases may have up to threegrid sizes. Each grid size must be at least three times the previousgrid size. For a more detailed discussion of spatial indexes andgrid sizes, see the ArcSDE Administration Guide PDF file and theArcSDE Configuration and Tuning Guide for <DBMS> PDF file.

When creating a new route feature class from scratch, a singledefault grid size of 1,000 will be used. This value should alwaysbe changed to an appropriate value.

When merging lines to create routes, calibrating route measureswith points, or migrating route data to a geodatabase, an attemptto borrow grid size settings from the input will be made. If gridsettings cannot be borrowed, default ones will be calculated foryou. Borrowed or default grid settings will not always beappropriate. For example, when merging lines to create routes,borrowed or default grid settings will be based on the inputfeatures. Because (potentially) many lines will be merged to createa single route, a grid size based on smaller features might not beappropriate for larger ones.

When an incorrect measure precision is used, measure accuracy can belost on a round-trip to the geodatabase.

1324.526

Subtract offset(1324.526 - (-1000))

Multiply by precision(2324.526 * 100)

232453(Value stored inGeodatabase)

Divide by precision(232453 / 100)

Add offset(2424.53 + (-1000))

1324.53

1324.526

Subtract offset(1324.526 - (-1000))

Multiply by precision(2324.526 * 1000)

2324526(Value stored inGeodatabase)

Divide by precision(2324526 / 1000)

Add offset(2324.526 + (-1000))

When a correct measure precision is used, measure accuracy ismaintained on a round-trip to the geodatabase.


Another consideration to make when merging lines to createroutes, calibrating route measures with points, or migrating routedata to a geodatabase is that borrowed or default grid settings arespecified in the same units as the coordinate system of the inputdata. If the output data is to be written to a different coordinatesystem, grid settings need to be specified in the units of theoutput coordinate system. For example, if the input feature classhas a geographic coordinate system and its units are decimaldegrees, the default grid size may be 10. If the output coordinatesystem is set to be UTM meters, the default grid size should beset to a value suitable for new units, such as 10,000.

If inappropriate grid settings are used, an error stating that thegrid size is too small may occur when storing features in a featureclass, or you may experience poor spatial search performance.


Creating routefeature classesYou create new route featureclasses in ArcCatalog. Whencreating a route feature class,you must define the geometryfield’s geometry type to bepolyline and indicate that it beable to store measure values.You also need to add a routeidentifier field. This fielduniquely identifies each route.

When creating a route featureclass in a geodatabase, youmust also define the spatialreference. Note that if you arecreating a feature class in apreexisting feature dataset, youneed only set the m domain.This is because all featureclasses in a feature datasetshare a common spatialreference, which was createdwhen the feature dataset wascreated. The m domain, how-ever, can be different for eachfeature class. This is becauseroute feature classes in afeature dataset often havedifferent units of measure—forexample, feet, meters, and miles.

When creating a shapefile thatwill store routes, you maychoose to define the coordinatesystem later. It will be classifiedas Unknown until that time. u

Creating a newstandalone feature classto store routes

1. Right-click the geodatabasein the Catalog tree in whichyou want to create a newroute feature class, point toNew, then click FeatureClass.

2. Type a name for the newfeature class. To create analias for this feature class,type the alias.

3. Click This feature class willstore ESRI simple features(e.g., point, line, polygon).

4. Click Next. u

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See Also

For details about using configura-tion keywords with ArcSDE, see theArcSDE Configuration and TuningGuide for <DBMS> PDF file.

Tip

Using another featureclass as a templateWhen creating a new feature classin a geodatabase, you can useanother feature class as a template.Click Import, navigate to thefeature class whose field definitionsyou want to copy, then click OK.You can edit the field names andtypes as required.

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The process of defining ashapefile’s attributes is separatefrom creating the shapefileitself. To create the routeidentifier plus all other fields,you need to right-click in theCatalog tree and click Propertiesto define the attributes. Notethat because a shapefile mustcontain at least one field, theinteger field ID has already beenadded. Add the appropriatefields to the shapefile, thendelete the default field.

If your geodatabase does notuse ArcSDE, skip to step 6.

5. Click Use configurationkeyword and click thekeyword you want to use ifyou want to create a featureclass with a custom storagekeyword.

6. Click Next.

7. Click the SHAPE field in theField Name column.

8. Click the field next to Alias, inField Properties, and enteran alias name to be used forthe SHAPE field.

9. Click the field next to AllowNULL values, click thedropdown arrow, then clickNo to prevent null shapesfrom being stored.

10. Click the field next toGeometry Type, click thedropdown arrow, then clickLine for the feature’s type.

11. Click the field next to thegrids and type the gridvalues to set the spatialindex grid parameters for thefeature class.

12. Click the field next toContains M values, click thedropdown arrow, then clickYes.

13. Click the Spatial ReferenceProperties button. u

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Tip

PrecisionThe size of a spatial domain (X/Y,Z, or M) is dependent on the valueof precision. When the precision ischanged, the maximum value forthe domain will change to fit thesize of the extent. Similarly, whenthe maximum value is changed, theprecision will change to fit theextent.

See Also

For details on how to create a newcoordinate system and forimportant information aboutspatial references and how theyaffect your data, see Building aGeodatabase.

14. Click Select, Import, or Newto set the feature class’scoordinate system.

15. Click the X/Y Domain tab.

16. Type the Min X and Preci-sion values for the X/YDomain.

17. Click the M Domain tab.

18. Type the Min and Precisionvalues for the M Domain.

19. Click OK. uT

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Tip

Creating a route featureclass in an existing featuredatasetThe process of creating a routefeature class in an existing featuredataset is similar to that of creatinga standalone route feature class.However, steps 13 through 15 arenot valid because all featureclasses in a feature dataset share acommon spatial reference, whichwas created when the featuredataset was created and cannot bechanged. The exception is the mdomain, which you should alwaysset.

Tip

Creating an index on theroute identifier fieldIt is recommended that you createan attribute index on the routeidentifier field. This index willimprove dynamic segmentationperformance.

See Also

For more information on creatinga feature class in a feature dataset,see Building a Geodatabase.

See Also

For more information on creatinga field index in a feature class, seeBuilding a Geodatabase.

20. Click the next blank row inthe Field Name column toadd the route identifier fieldto the feature class and typea new field name—forexample, Route_ID.

21. Click in the Data Typecolumn next to the newfield’s name and select itsdata type.

22. Enter or select the propertiesfor the Field Properties.

23. Repeat steps 20 through 22until fields for the featureclass have been defined.

24. Click Finish.

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Creating a new shapefileto store routes

1. Right-click the folder in theCatalog tree in which youwant to create a newshapefile, point to New, thenclick Shapefile.

2. Type a name for the newshapefile.

3. Click the Feature Typedropdown arrow and clickPolyline.

4. Check Coordinates willcontain M values.

5. Click Edit to define theshapefile’s coordinatesystem.

When you are finishedsetting the shapefile’scoordinate system (step 7),you will be returned to thisdialog box. u

See Also

For more information on creatingshapefiles, see Using ArcCatalog.

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Tip

Creating an index on theroute identifier fieldIt is recommended that you createan attribute index on the routeidentifier field. You can do this bychecking the route identifier youcreated, in the Shapefile PropertiesIndexes tab. This index willimprove dynamic segmentationperformance.

See Also

For more information on creatinga field index in a shapefile, seeUsing ArcCatalog.

6. Click Select, Import, or Newto set the shapefile’s spatialreference.

7. Click OK.

8. Click OK to create theshapefile.

9. Right-click the feature classin the Catalog tree and clickProperties.

This will open the Propertiesdialog box, so you can addthe route identifier field to theshapefile. u

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Deleting the default ID fieldThe integer field ID is a defaultfield and can be deleted onceanother field has been added to theshapefile.

10. Click the Fields tab.

11. Click the next blank row inthe Field Name column andtype a name for the routeidentifier field.

12. Click in the Data Typecolumn next to the newfield’s name and click itsdata type.

13. Click in the Field Propertieslist and type the propertiesfor the new field.

14. Repeat steps 10 through 13until all the shapefiles’ fieldshave been defined.

15. Click OK.

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Creating routesfrom existing linesYou create routes from existinglines using the Create Routestool in the Linear Referencingtoolbox in ArcToolbox.

The input feature classes can beany supported format. Thisincludes coverage, shapefile,personal and enterprise geodata-base, and CAD data.

The linear features used asinput, sharing a commonidentifier, are merged to create asingle route. As the input linearfeatures are merged, the routemeasures are determined in oneof three ways:

• The geometric lengths of theinput features are used toaccumulate the measures.

• A value stored in a measurefield is used to accumulatethe measures.

• The values stored in from-and to-measure fields areused to set the measures.

With the first two options, youchoose whether the outputroutes will have continuousmeasures when there aredisjointed parts.

Also with the first two options,you control the directionmeasures are assigned to theroutes by specifying the u

1. Click the Show/HideArcToolbox button on theStandard toolbar to showArcToolbox.

2. Expand the Linear Referenc-ing Tools.

3. Double-click the CreateRoutes tool.

4. Type the Input Line Featuresfilename and path, click theBrowse button to select it, orclick the dropdown arrow toselect a layer.

5. Click the Route IdentifierField dropdown arrow andclick the route identifier field.

6. Type the Output RouteFeature Class filename andpath or click the Browsebutton to specify the outputlocation.

7. Click the Measure Sourcedropdown arrow and clickthe option in which you wantthe output route measures tobe obtained.

8. For point events, click theMeasure Field dropdownarrow and click the measurefield.

For line events, click theFrom-Measure Field drop-down arrow and click thefrom-measure field. Click theTo-Measure Field dropdownarrow and click the to-measure field. u

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coordinate priority of thestarting measure. The coordi-nate priority can be upper left,upper right, lower left, or lowerright. These options aredetermined by placing theminimum bounding rectanglearound the input features thatare going to be merged to createone route.

The output routes can bewritten to a shapefile or ageodatabase feature class.When writing to a geodatabase,you should always have anappropriate m domain set. If it isnot set, a default m domain willbe calculated for you, but thismight not accurately reflectyour data.

9. Optionally, click the Coordi-nate Priority dropdown arrowand click a coordinate priority.This becomes active when aMeasure Source is LENGTHor ONE_FIELD.

10. Click Environments.

11. Expand GeodatabaseSettings.

12. Click the Output M Domaindropdown arrow and click AsSpecified Below.

13. Type a value for Min M andPrecision.

14. Click OK to close eachdialog box.

Tip

Set environment settingsfor multiple operationsWhen using the same environmentsettings for multiple geoprocessingoperations, set them at theapplication level. These environ-ment settings can be accessedthrough Tools | Options on theGeoprocessing tab.

Tip

Create Routes WizardThe Create Routes Wizard isavailable in ArcCatalog via theCustomize dialog box. You can addit to your context window ortoolbars.

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3. Double-click the CalibrateRoutes tool.

4. Type the Input Route Fea-tures filename and path orclick the Browse button toselect it.


6. Type the Input Point Featuresfilename and path or click theBrowse button to select it.

7. Click the Point Identifier Fielddropdown arrow and clickthe point identifier field.

8. Click the Measure Fielddropdown arrow and clickthe measure field.

9. Type the Output RouteFeature Class filename andpath or click the Browsebutton to specify the outputlocation.

10. Optionally, click the MeasureCalculation Method drop-down arrow and click ameasure calculationmethod. u

Calibratingroutes with pointsWhen calibrating routes withpoints, you can choose toexclude routes without anyassociated calibration pointsfrom the output.

The calibration of whole orpartial routes is possible.

Route measures can be updatedusing the shortest pathdistance between the calibra-tion points or using the existingmeasure distance between thepoints. In most applications,using the shortest pathdistance between the calibra-tion points will be sufficient.Calibrating by measure distanceshould be used on data forwhich the length-to-measureratio is not consistent atvarious locations along theinput routes.

When calibrating using theshortest path distance, you canchoose whether the outputroutes will have continuousmeasures when there aredisjointed parts.

A search radius can be speci-fied to limit how far a calibrationpoint can be from a route.Points outside the search radiuswill not be used by the calibra-tion process.

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11. Optionally, type the SearchRadius that will be used tomatch the points to theroutes and click the drop-down arrow to select the unitof measurement.

12. Click Environments. u

Tip

Calibrate Routes WizardThe Calibrate Routes Wizard isavailable in ArcCatalog via theCustomize dialog box. You can addit to your context window ortoolbars.

See Also

For more information on adding acommand to a context menu, seeUsing ArcCatalog.

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For information on the optionalparameters, click Show Help on thetool’s dialog box.







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Migrating routedata to ageodatabaseThe Feature Class to FeatureClass and Feature Class toGeodatabase scripts inArcToolbox allow you tomigrate route data from anysupported format into ageodatabase. During theconversion, all measure valuesare preserved. The example inthis section converts acoverage route system to ageodatabase feature class.

When migrating to a geodata-base, you can create astandalone feature class or afeature class in an existingdataset.

When creating or importing afeature class or feature dataset,you can specifiy the coordinatesystem, spatial domain, andprecision in the environmentsettings. Set the spatial domainand precision carefully sinceonce you’ve created the featureclass the attributes cannot bechanged.

If you’re creating a featureclass in an existing featuredataset, the new feature classwill automatically take on thesame coordinate system, spatialdomain, and precision as thefeature dataset, so there is no u

Migrating a coverageroute system to ageodatabase

1. Right-click the coverageroute system in the Catalogtree that you want to migrate,point to Export, then click ToGeodatabase (single).

Alternatively, access theFeature Class to FeatureClass tool directly in theArcToolbox ConversionTools, To Geodatabasetoolset.

2. Type the value of the OutputWorkspace parameter, orclick the Browse button tochoose this value.

NOTE: The Output Workspacemust already exist.

3. Type the value of the NewFeature Class Nameparameter.

4. Optionally, type a value forthe Expression parameter, orclick the Expression buttonand use the Query Builder tobuild the value for theparameter.

5. Optionally, edit the Field Info.

Click a value in theNewFieldName field tochange the field name.

Click a value in the Visiblefield and click TRUE orFALSE to carry this field intothe new feature class. u

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need to specify the spatialreference parameters in theEnvironment Settings beforeyou import. The exception is them domain, which you shouldalways set when migrating datato a geodatabase. For moreinformation about spatialreferences, see Building aGeodatabase.

You can optionally specifywhich fields to import and howto name them. You can also limitwhich features are imported byspecifying an expression or afield list.

6. Click Environments.

7. Expand General Settings.

8. Click the Output has MValues dropdown arrow andclick Same As Input.





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IN THIS CHAPTER

71

Displaying and querying routes and events 5• The route identifier field

• Querying route data

• Hatching

• Displaying hatches

• Manipulating the text on hatches

• Hatch styles

• Route measure anomalies

• Dynamic segmentation

• Adding route events

Geographic data is represented on a map as a layer. Route and event dataaren’t any different. ArcMap provides you with the tools to add route andevent data to a map as a layer. ArcMap also provides you with many toolsfor symbolizing and labeling route and event layers in a wide variety ofways.

Once your route and event data have been added to a map, you can gainmuch insight by just looking at it. You may, however, want to discover spatialrelationships that are not apparent to the naked eye. ArcMap provides youwith a number of tools to find answers to questions such as Where is...?What is...? Where is the closest...? What’s inside...? and Whatintersects...? In addition to these tools, ArcMap provides you with toolsdesigned specifically for linear referencing data. With these additional tools,you can:

• Find route and measure information by pointing at your map.

• Find route locations on a map by providing route and measureinformation.

For more information on displaying and querying your data, refer to UsingArcMap.


The routeidentifier fieldWhen route data is added toArcMap, additional layerproperties are exposed forworking with this layer. One ofthese new properties is theroute identifier field.

The route identifier uniquelyidentifies each route within afeature class. The routeidentifier field can be anynumeric or character field inyour route feature class.

Setting the route identifier fieldsaves steps when using manyof the linear referencing anddynamic segmentation dialogboxes and wizards in ArcMap.

Setting the routeidentifier field

1. Right-click the route layer inthe table of contents andclick Properties.


3. Click the Route Identifierdropdown arrow and clickthe field that is to be used asthe route identifier.

4. Click OK.

Tip

Saving the route identifierfieldIf the layer is saved as a layer file(.lyr), the route identifier field issaved as well.

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DISPLAYING AND QUERYING ROUTES AND EVENTS 73

Adding the Identify RouteLocations tool

1. Click the Tools menu andclick Customize.


3. Click Linear Referencing inthe Categories list.

4. Drag the Identify RouteLocations tool to the toolbarof your choice—for example,the Tools toolbar.

5. Click Close.

Querying routedataA lot of information can bederived from a map by justlooking at it. There are times,however, when you need toknow more. Because of this,ArcMap provides you with thetools for querying your maps ina wide variety of ways. Inaddition to the standard suiteof map query tools, you canalso find and identify routelocations.

See Also

For more information on queryingmaps or adding commands to atoolbar or menu, see UsingArcMap.

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Identifying routelocations

1. Click the Identify RouteLocations tool.

2. Click the location on theroute where you want routemeasure information.

Tip

Route Identifier fieldThe values displayed on thebranches of the route locations treecorrespond to the values in theRoute Identifier field. See ‘Settingthe route identifier field’ in thischapter.

Tip

Layer dropdown listUse the Layer dropdown list toidentify route locations fromspecific layers only.

Tip

The Identify RouteLocations tool is notenabledThe Identify Route Locations toolwill not be enabled when there areno route layers in the map.

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Labeling an identifiedroute location with a textgraphic

1. Right-click on a found routelocation and click Label routelocation.

See Also

When you draw or label a routelocation, ArcMap default symbolproperties are used. For moreinformation on ArcMap defaultsymbol properties, see UsingArcMap.

Tip

Controlling the text of theroute locationWhen a route location is labeled,the text comes from two sources.The route identifier reflects thename of the layer’s route identifierfield. The measure reflects thedescription that is displayed on theright panel of the Identify RouteLocations dialog box.

Tip

Changing what informationis displayedRight-click anywhere on the rightpanel of the Identify Route Loca-tions dialog box to expose a contextmenu that allows you to controlwhich route location information isdisplayed.

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Finding a route location

1. Click the Find tool on theArcMap Tools toolbar.

2. Click the Route Locationstab.

3. Click the Route Referencedropdown arrow and clickthe layer that is the routereference.

4. Optionally, click the LoadRoutes button.

5. Click the Route dropdownarrow and click the route.

Alternatively, type the routeidentifier in the Routedropdown list.

6. Click whether the routelocation will be point or line.

7. Type the route locationinformation.

8. Click Find.

9. Right-click the found routelocation and explore thecontext choices available toyou.

Tip

Route identifier fieldThe Find dialog box pays attentionto the route identifier field. If youhave not set the route identifierfield, then you will need to click theRoute Identifier dropdown arrowand click the field to be used for theroute identifier between steps 3 and4. See ‘Setting the route identifierfield’ in this chapter.

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Hatching

Hatching is a type of labeling that is designed to post and labelhatch marks or symbols at a regular interval along measured linearfeatures. Hatching can be used for both distance-based andnondistance-based measures. Distance-based measures includekilometers, miles, feet, and meters. Nondistance-based measuresinclude seismic shotpoint numbers where measure valuesgenerally increase in even intervals based on some nominaldistance.

0 cm 1 2 3 4 5 6

In this example, the ruler represents a hatch class. The interval of thehatches is 0.1 cm (1 mm). There are three hatch definitions. Each definitionis placed at a multiple of the hatch interval—10, 5, and 1, respectively.Some hatch definitions are labeled, while others are not.

Hatching can be used in applications with either distance-based ornondistance-based measures.

Hatching concepts

To display hatches on a layer, you must define one or more hatchclasses for the features you wish to hatch. Each hatch class iscomposed of one or more hatch definitions.

The easiest way to understand hatch classes and hatchdefinitions is to use a ruler analogy. On a ruler, there is a series ofvertical lines, or hatches, separated by a regular interval. Forexample, on a centimeter (cm) ruler, the hatches are typicallyspaced every millimeter (mm). One millimeter is 1/10 of acentimeter, so the hatch interval is 0.1.

Not all the hatches on a ruler are the same. Some are longer thanothers. Further, some have text, while others do not. On acentimeter ruler, the hatches placed at every millimeter (0.1 cm) arethe shortest. The hatches placed at every 5 millimeters (0.5 cm)

are a bit longer. The hatches placed every 10 millimeters (1 cm) arethe longest. The longest hatches typically have text to indicatethe measure value.

In this example, the ruler is a hatch class. It is a container for thehatch definitions. There are three hatch definitions. Eachdefinition is placed at a multiple of the hatch interval. The longesthatches are placed at every 0.1 x 10 measure units. The secondlongest hatches are placed at every 0.1 x 5 measure units. Theshortest hatches are placed at every 0.1 x 1 measure units.

When placed on a map, hatch definitions within a single hatchclass will not draw on top of one another.

There is a special type of hatch definition known as an end hatchdefinition. An end hatch definition pays no attention to thespecified hatch interval. Rather, it simply draws hatch marks at thelow and high measure of a linear feature. For cases in whichhatches get placed too close together near the end of a feature, itis possible to specify an end hatch tolerance, which preventscertain hatches from drawing if they are within the tolerance(specified in measure units) of an end hatch.

Imagine that you have linear features whose measures are inmiles. You want to place a hatch every quarter of a mile. This is ahatch interval of 0.25. Further, you want the hatches placed atevery 0.25, 0.5, and 1 mile to look different (different length,different color). You want the hatches every mile to have text.Last, you want hatches at the ends of the feature. These endhatches are to look different from all other hatches and will have


Hatching options

There are many ways in which you can control how hatchesappear on a map. The following illustrate some of the wayshatches can be manipulated.

All of the hatch definitions ina hatch class can be offsetby the same amount.Alternately, each individualhatch definition can have itsown offset.

Each hatch definition can bedisplayed to the left of,centered on, or to the rightof a feature. When set tocenter, hatches will belabeled to the left of thefeature.

Hatching can start at ameasure location other thanthe low measure. Further,hatching can finish at alocation other than the highmeasure.

In the case in which afeature’s geometry hasmultiple parts, it is possibleto apply hatches to thefeature as a whole or to eachpart individually.

How hatching worksIn this example, the line is 4.0 miles long, and the hatchinterval is 0.25. To make hatches look like the following, fourhatch definitions are necessary.

Step 1: The hatch definition with the highest multiple of thehatch interval—HatchDef(4)—is placed first. Because an endhatch definition has been specified, no hatches are placed atthe ends even though the measure values are divisible bythe hatch interval.

Step 2: The hatch definition with the next highest multiple ofthe hatch interval—HatchDef(2)—is placed. These hatcheswill not overwrite hatches that have already been placed.

HatchDef(End)—placed only at route ends. Has text.

HatchDef(1)—placed every 0.25 miles (0.25 x 1). Does not have text.

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HatchDef(2)—placed every 0.5 miles (0.25 x 2). Does not have text.

HatchDef(4)—placed every 1 mile (0.25 x 4). Has text.

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Step 3: The hatch definition with the next highest multiple ofthe hatch interval—HatchDef(1)—is placed. These hatcheswill not overwrite hatches that have already been placed.

Step 4: The end hatch definition—HatchDef(End)—will beplaced.

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text. The following example demonstrates conceptually howhatching works in this scenario.


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By default, the placement ofhatches is adjusted to thehatch interval. This meansthat in cases in which a line’slow measure is not divisibleby the interval, the firsthatch will be placed at thefirst measure value that is divisible by the hatch interval. Forexample, a line whose measures range from 1.1 to 5.2 will have itsfirst hatch placed at 1.25 when the hatch interval is 0.25. Thisbehavior can be turned off. Note that end hatch definitions arenot affected by this setting and are not shown in this example.

In cases in which a feature’shigh measure is not divisibleby the hatch interval and anend hatch definition hasbeen defined, it is possible toget two hatches that are very close to or on top of one another.To avoid this, it is possible to specify an end hatch tolerance,which informs the hatching algorithm to not place hatches whenthey fall within the tolerance of the end hatch. The end hatchtolerance is specified in route measure units, and its value istypically set to a value that is less than the hatch interval.

Hatches are drawn perpendicular to the feature. It is possible tospecify a supplemental anglethat is added to thecalculated angle.

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Hatch text is flipped as thedirection of the featurechanges. This is to makethe text more readable. Thiscan be turned off so thetext is always oriented inthe direction of increasingmeasure.

Hatches can also be placedonly at the route ends. In thiscase, it is not necessary tospecify a hatch interval.

Creating and managinghatches

Hatches are a feature layer property. As such, hatches are createdand managed on the Layer Properties dialog box.

The Hatches tab on the Layer Properties dialog box has threeviews: the Hatch Class view, the Hatch Definition view, and theEnd Hatch Definition view. The hatch class view is enabled whena hatch class is selected in the hatch tree. The hatch definitionview is enabled when a hatch definition is selected in the hatchtree. The end hatch definition view is enabled when an end hatchdefinition is selected in the hatch tree.

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Hatch Class view

Note that a hatch class is highlighted in the hatch tree.

The Hatches tab is only available forlinear feature layers with measures.

Hatch classes andhatch definitions can

be defined but notvisible.

The preview indicates what the hatches inthe currently selected hatch class will looklike.

Each hatch class canbe visible or not

visible. This is usefulwhen more than onehatch class has been

defined.

A hatch class alwayshas at least one hatch

definition.

Right-clicking a hatchclass in the tree

displays a contextmenu.

Hatches can beimported fromanother layer in themap document orfrom a layer file (.lyr).

A single hatchinterval can beapplied to allfeatures, or differenthatch intervals canbe stored in a field.The hatch interval isalways specified inthe same units as theroute measures.

A hatch style can beapplied to theselected hatch class.

It is possible to limit thenumber of features that arehatched in each class byusing a SQL query.

The drawing of hatches atcertain scales can besuppressed.

Displays the Hatch PlacementOptions dialog box. These optionscontrol things such as the start andend measure ranges and whether allhatch definitions should be offset.


Hatch Definition view

Note that a hatch definition is highlighted in the hatch tree.

The selected hatch definition ishighlighted using the ArcMapselection color.

A hatch definition’sname includes the

multiple of the hatchinterval at which the

hatches are to beplaced.

No two definitionswithin the same class

can have the samemultiple of the hatch

interval.

Right-clicking a hatchdefinition in the tree

displays a contextmenu.

A hatch definition is placed at a multiple of thehatch interval. The hatch interval is set on theHatch Class view.

Each hatch definition can be labeledwith the route measure.

A hatch definitioncan be symbolizedwith either a line ormarker symbol.

The line length andlateral offsetproperties arespecified in the unitsthat are set on theHatch PlacementOptions dialog box.

Displays the HatchOrientation dialogbox.

Displays the LabelSettings dialog box.


End Hatch Definition view

Note that an end hatch definition is highlighted in the hatch tree.

An end hatchdefinition is a special

type of hatchdefinition. Thesehatches are onlyplaced at the line

ends.

Right-clicking an endhatch definition in the

tree displays acontext menu.

If any of the hatchesfrom the other hatchdefinitions in thesame class arewithin the end hatchtolerance, they willnot be placed.

The end hatchtolerance is specifiedin route measureunits.

The selected end hatch definition ishighlighted using ArcMap selectioncolor.


Hatch Placement Options dialog box

This dialog box is initiated by clicking the Hatch Placement button on the Hatch Class view. The settings made on this dialog box applyto all the hatch definitions that make up the selected hatch class.

The distance units apply to offsetsand hatch definition lengths. They

do not refer in any way to the hatchinterval, which is specified in route

measure units.

The default distance units are thesame as the active data frame’s

display units.

All hatch definitions in a class canbe offset by a value. A single offsetcan be applied to all features, ordifferent offsets can be stored in afield.

Note that it is possible to offsetindividual hatch definitions. This isdone on the Hatch Definition view.

It is possible to start hatching at avalue other than the lowest

measure. A single value can beapplied to all features, or different

values can be stored in a field.These values are always specified

in route measure units.

It is possible to finish hatching at avalue other than the highestmeasure. A single value can beapplied to all features, or differentvalues can be stored in a field.These values are always specifiedin route measure units.In some cases, the low measure of

a line is not exactly divisible by thehatch interval. The first hatchplaced will be adjusted to a

measure value that is divisible bythe hatch interval. This behavior

can be turned off.

In some cases, a line might havemultiple parts. It is possible to applyall hatch settings to each partindividually.


Hatch Orientation dialog box

This dialog box is initiated by clicking the Hatch Orientation button on the Hatch Definition view. The settings made on this dialog boxapply only to the currently selected hatch definition.

Label Settings dialog box

This dialog box is initiated by clicking the Label Settings button on the Hatch Definition view. The settings made on this dialog boxapply only to the currently selected hatch definition.

A hatch definition can be drawn tothe left, right, or center of the line.Text is placed on the left side forthe center option.

The default is to draw line hatchesperpendicular to the line.

By default, a hatch’s text will onlybe the measure.

Alternatively, a prefix and/or suffixcan be plotted before the measurevalues.

Lastly, label expressions can bebuilt using VBScript or JavaScript.

The precision of the value isdisplayed for the hatch’s text. Themeasure value will be rounded offto the precision specified.

This option is not available when atext expression is being used.

The default is to plot the negativesign for negative measure values.

The default is to flip the text as thedirection of the line changes.


DisplayinghatchesHatches are line or markersymbols displayed on top offeatures at an interval specifiedin route measure units. Hatchesallow you to make maps that aresuitable for almost any applica-tion that uses measured linearfeatures.

Layers based on linear featureswith measures always have atleast one hatch classassociated with them. Initially,the default hatch class containsone hatch definition. Additionalhatch definitions can be addedto this hatch class. Each hatchdefinition has its own set ofproperties. These include themultiple of the hatch interval atwhich the hatches in the hatchdefinition will be placed, theline or marker symbol of thehatches, and whether thehatches will be labeled. The useof multiple hatch definitionsallows you to design complexhatching schemes.

Because hatch definitions mightshare many of the sameproperties, it is possible tocopy the properties of a hatchdefinition and change only theproperties that are different.

Any number of hatch classescan be associated with a layer. u

Hatching features in alayer

1. Right-click the layer in thetable of contents that youwant to hatch and clickProperties.

2. Click the Hatches tab.

3. Check Hatch features in thislayer.

4. Type an appropriate Hatchinterval.

5. Click Hatch Def(1).

The Hatch Definition viewbecomes active.

6. Type an appropriate Linelength. u

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Each hatch class can containany number of hatch defini-tions. One reason to createmultiple hatch classes is tohatch some features one wayand other features another way.To do this, you would associatea SQL query with your hatchclasses. Another reason to havemultiple classes is to havehatches appear differently atdifferent scales. To do this, youwould specify a scale rangewith your hatch classes.

In situations when you needhatches at the end of features,you need to add an end hatchdefinition to the hatch class.

To appear on a map, hatchesmust be turned on via a checkbox. Note that it is possible toturn each individual class on oroff as well.

To save time, it is possible toimport hatches from anotherlayer. These layers may be inthe map or may have beenstored on disk as a layer file(.lyr). Note that if any of thehatch properties in the layeryou are trying to import fromare based on a field—forexample, the hatch interval—then that field must exist in thelayer you are trying to importto.

Another time-saving method isthe use of hatch styles. Formore information on hatch u

7. Right-click the hatch classand click Add HatchDefinition.

The Hatch Definition viewbecomes active.

8. Type an appropriate multipleof the hatch interval.

9. Type an appropriate Linelength.

10. Check Label thesehatches. u

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Tip

Stopping the drawingprocessIf you selected a hatch interval thatis too small, too many hatches willbe drawn on the screen. Thedrawing process can be stopped bypressing the Esc key.

Tip

Hatches do not appear onthe mapIf hatches do not appear after youhave set up your hatch classes andhatch definitions, make sure that(1) the Hatch features in this layerbox is checked, (2) the box besideeach hatch class in the tree ischecked, (3) the specified hatchinterval is appropriate for the data,and (4) all hatch definitions thatuse a line symbol have an appro-priate line length specified.

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11. Right-click the hatch classand click Add End HatchDefinition.

The End Hatch Definitionview becomes active.

12. Type an appropriate Endhatch tolerance if necessary.

13. Type an appropriate Linelength.

14. Check Label these hatches.

15. Click OK.

styles, see ‘Hatch styles’ in thischapter.

Hatches do not respect theArcMap overposting environ-ment. As such, hatches andtheir labels can overlap oneanother. To avoid this, specify-ing a different hatch intervaloften alleviates the problem. Insome situations, however, it isdesirable to convert hatches tographics so they can be movedon the map.


Importing hatches fromanother layer



3. Click Import.

4. Click the Layer dropdownarrow and click the layer youwant to import hatches from.

Alternately, click the Browsebutton and navigate to thelayer file (.lyr) that you wantto import hatches from.

5. Click OK on the ImportHatches dialog box.

6. Click OK.

Tip

Making hatches and theirlabels bigger when youzoom inAs you zoom in and out on yourmap, the sizes of the hatches andtheir labels do not change. If youwant the hatches and text to scalewith the map, set a reference scale.Right-click the data frame and clickSet Reference Scale.

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Copying a hatchdefinition’s properties

1. Right-click the hatchdefinition that you want todefine the properties for andclick Copy Properties From.

2. Click the hatch definitiondropdown arrow and clickthe hatch definition whoseproperties you want to copy.

3. Click OK.

Tip

Removing hatch classesand hatch definitionsThe currently selected hatch classor hatch definition can be removedby right-clicking and clickingRemove or by pressing the Deletekey.

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Adding the ConvertHatches to Graphicscommand

1. Click the Tools menu andclick Customize.

2. Click the Toolbars tab.

3. Check Context Menus in theToolbars list.

The Context Menus toolbarappears. u

Tip

Why convert hatches tographics?You can convert hatches tographics so they can be moved,resized, and edited on the map.This option is useful for carto-graphic purposes.

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See Also

For more information on addingcommands to a toolbar or menu,see Using ArcMap.

44. Click the Context Menusdropdown list and clickFeature Layer Context Menu.


6. Click Linear Referencing inthe Categories list.

7. Click the Save in dropdownarrow and click where youwant your customizationsaved.

8. Drag the Convert Hatches ToGraphics command to theFeature Layer Context Menu.

9. Click Close.

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See Also

For more information on graphicsor creating and editing annotationtargets, see Using ArcMap.

Converting hatches tographics

1. Right-click the layer in thetable of contents whosehatches you want to convertto graphics and click ConvertHatches to Graphics.

2. Click the features for whichyou want to create graphics.

3. Uncheck any hatch classesyou do not want converted tographics if appropriate.

4. Click the Target annotationgroup dropdown arrow andclick the annotation targetwhere you want to add thegraphics.

Alternately, type the name ofa new target annotationgroup.

5. Click OK.Tip

Drawing only convertedgraphicsIf you choose to only draw theconverted graphics, each hatchclass that was converted will beunchecked on the Hatches tab onthe Layer Properties dialog box.

Tip

Where should you savegraphics?If you want to display the graphicsonly in a particular map, storethem in the map. If you want to usethem in other maps, store them inan annotation feature class in ageodatabase.

Tip

Why does my targetannotation group notappear?If your desired target is a geodata-base annotation feature class, youmust first start an edit session.Then, you must set the ArcMapactive annotation target to be thatfeature class.

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Manipulating thetext on hatchesEvery hatch definition may ormay not be labeled. Whenlabeled, you have control overthings such as the text symbolthat is used and whether or notthe text will automatically beflipped as the direction of theroute changes.

By default, the text associatedwith a hatch is the routemeasure at the hatch location.This text can be supplementedwith a prefix and/or suffix value.

For more advanced needs, youcan programmatically generate ahatch’s text by writing a scriptin Microsoft® VBScript™ orJavaScript™. Your script caninclude any valid statementsthose programming languagessupport.

When writing a script, youaccess the route measure foreach hatch using theesri__measure constant value.

The script used in the followingexample tells the hatchingalgorithm not to label a hatch ifits measure value is within0.1 measure units of the valuestored in a field named MMAX.This method can be usedinstead of an end hatchtolerance, which tells the hatchalgorithm not to draw either thehatch or its label.

Generating the text onhatches using a script



3. Follow steps 3 through 14 of‘Hatching features in a layer’if necessary.

4. Click the hatch definition ofyour choice.

5. Make sure the Label thesehatches check box ischecked.

6. Click Label Settings.

7. Click Build a text expression.

8. Click Expression. u

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See Also

For more information on VBScriptand/or JavaScript, click the Helpbutton on the Hatch Text Expres-sion dialog box.

Function FindLabel (esri__measure, [MMAX])

mmax = [MMAX]

m = esri__measure

if (mmax - m) <= 0.1 then

FindLabel = ""

else

FindLabel = cstr(round(m,2))

end if

End Function

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9. Check Advanced.

10. Type a VBScript orJavaScript expression.

ArcMap automaticallycreates a FindLabel functionin your code. FindLabelshould evaluate to a string.

11. Click Verify to make surethere are no syntax errors.

12. Click OK on the Hatch TextExpression dialog box.

13. Click OK on the LabelSettings dialog box.

14. Click OK.


Hatch stylesA hatch style stores thesymbols and the settings of thehatch definitions that make up ahatch class. Hatch styles helpyou maintain standards fordisplaying your hatches onmultiple maps with multiple datasources.

When setting up hatch styles, itis important to note that someof the properties available whensetting up a hatch class are notavailable when setting up ahatch style. These are theproperties that are based onattributes, such as class leveloffsets, start measures, andfinish measures.

Like any other style in ArcMap,hatch styles are stored in astyle file (.style). Unlike otherstyles, however, there are noindustry-standard hatch stylesthat come with ArcMap. It is upto you to create your own hatchstyles.

Whether you are creating a newhatch style from scratch oraltering the properties of anexisting one, you use the StyleManager dialog box to workwith hatch styles.

Creating a new hatchstyle in the Style Manager

1. Click the Tools menu, point toStyles, then click StyleManager.

2. Click the Hatches folder inthe style tree in the ESRIstyle file (.style) in which youwant to create a new hatchstyle.

3. Right-click in the open spacein the Style contents window,point to New, then clickHatch.

4. Set the style’s properties onthe Hatch Style propertiesdialog box and click OK.

5. Name the new hatch style.

6. Click close to close the StyleManager dialog box.

See Also

For more information on styles, seeUsing ArcMap.

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Saving a hatch class as ahatch style

1. Click the hatch class that youwant to save as a hatch style.

2. Click Hatch Styles.

3. Click Save.

4. Type the name of the newhatch style.

5. Click OK.

6. Click OK on the Hatch Styledialog box.

7. Click Apply.

Tip

Accessing the Hatch Styledialog boxYou can also access the Hatch Styledialog box by right-clicking a hatchclass in the hatch tree and selectingHatch Styles.

Tip

Where are my hatch stylessaved?When you save a hatch class as astyle, it is saved to your ownpersonal style, which is locatedunder the Windows install location(e.g., C:\Documents andSettings\<user>\ApplicationData\ESRI\ArcMap). You can usethe Style Manager to move it to adifferent style file.

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Applying a hatch style toa hatch class

1. Click the hatch class to whichyou want to apply a hatchstyle.

2. Click Hatch Styles.

3. Click the hatch style youwant to use.

4. Click OK.

5. Click Apply.

Tip

Applying a hatch styleIf you apply a hatch style to a hatchclass that already has some hatchdefinitions in addition to the defaultdefinition, they will be overwrittenby the hatch definitions in the hatchstyle.

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Route measureanomaliesThe ArcGIS system does notplace any constraints on routemeasures. Route measures canalways increase with respect toa route’s digitized direction,always decrease with respect toa route’s digitized direction, orbe some combination ofincreasing and decreasingvalues. Lastly, route measuresmay be unknown (NaN).

Route measure anomalies areportions of routes where themeasures do not conform to thestandards your applicationexpects. With the ability todisplay what you deem to beroute measure anomalies inArcMap, you can ensure thatthe measures on your routesconform to the needs of yourapplication. Seeing where routemeasure anomalies occur canhelp you isolate routes that mayneed to have their measuresedited.

Displaying routemeasure anomalies

1. Right-click the route layer inthe table of contents andclick Properties.


3. Click the Route MeasureAnomalies you want todisplay and change thesymbology as necessary.

Tip

Scale ranges and SQLqueriesUse a scale range and/or a SQLquery to control how routemeasure anomalies are displayed.

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Geographic data is represented on a map as a layer. Route eventsare no different. To display route events on a map, however, youmust first define the parameters of the relationship between thetable storing the events and the routes that the events reference.

Dynamic segmentation (DynSeg) is the process of computing themap location (shape) of events stored in an event table. Dynamicsegmentation is what allows multiple sets of attributes to beassociated with any portion of a linear feature.

The result of the dynamic segmentation process is a dynamicfeature class known as a route event source. A route event sourcecan serve as the data source of a feature layer in ArcMap.

Dynamic segmentation

0.2 11.12.00

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STOP

C3B2B2B2A1A1A1RID MILE

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B2C3D4

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C3D4

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Point MPoint MPoint MPoint MPoint MPoint MPoint M

ShapeSTOP

C3B2B2B2A1A1A1RID MILE

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Event table

Routes

Route event source Event layer

The result of the dynamic segmentation process can be displayed on amap as a layer.

For the most part, a dynamic feature layer behaves like any otherfeature layer. It is possible to decide whether or not to display it,the scale at which it should be visible, what features or subset offeatures to display, how to draw the features, whether to store itas a layer file (.lyr), whether to export it, and so on.

A route event source can be edited in ArcMap. It is important tonote, however, that it is possible to only edit the attributes. Theshapes of a route event source, however, cannot be editedbecause they are generated by the dynamic segmentationprocess. When you edit a route event, you are actually editingthe underlying event table. As such, there may be some editinglimitations imposed by the event table. For example, it is notpossible to directly edit the attributes of a route event sourcecreated from a delimited text file table since ArcMap does notallow text files to be edited directly.

Advanced dynamic segmentation options

Point events as multipoint features

When a point event is located along a route, a point feature iscreated. In some applications, however, route measures are notunique. For these applications, it might be desirable to havepoint events treated as multipoint features.

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Point events can be located along routes as point features or multipointfeatures.


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The dynamic segmentation process can calculate the angle of a route at apoint event’s location.

Event locating angles

When a point event is located along a route, it is often desirableto know the angle of the route where the event is placed. Forexample, you might need to rotate the marker symbol that is usedto display the event so it is oriented to the route and not the map.Further, you might need to rotate a point event’s label.

The dynamic segmentation process can calculate either thenormal (perpendicular) or tangent angle. Further, it is possible tocalculate the complement of these angles so you can, for example,control the side of the route on which a rotated label appears.

Event locating errors

The dynamic segmentation process creates a shape for each rowin the input route event table. In some cases, however, the shapeof the event feature might be empty. This happens when therewas some reason that the event could not be properly located. Inother cases, an event can only be partially located; this happensfor line events only.

The dynamic segmentation process can expose the locating error,if any, for each event in an event table as a field. This field isuseful when performing quality assurance tests on your eventtables.

Event offsets

In some applications, events with an offset are to be drawn to theright of the route. In other applications, events with an offset areto be drawn to the left. The dynamic segmentation process allowsyou to control which side of the route events with offsets isdrawn.

4.5 NO ERROR12.716.2

01.3

ROUTE MEASURE NOT FOUNDROUTE NOT FOUNDROUTE NOT FOUND

LOC_ERROR

B2B2A1A1A1RID MILE

NO ERROR

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NO ERRORPARTIAL MATCH FOR THE TO-MEASUREROUTE NOT FOUND

LOC_ERRORTMP

B2A1A1RID FMP

17.0

The dynamic segmentation process is aware of the locating status of eachevent. This information can be exposed as a field.


Adding routeeventsA route location describes aportion of a route or a singlelocation along a route. Whenroute locations are stored intables, they are known asroute event tables. Routeevent tables are typicallyorganized around a commontheme. For example, an eventtable for highways mightinclude speed limits, year ofresurfacing, present condition,and accidents.

There are two types of routeevents: point and line. Point u

Tip

Attribute indexesDynamic segmentation perfor-mance is improved with the use ofan attribute index on the routeidentifier field in both the eventtable and the route reference.

Tip

Displaying route eventsRight-click an event table in thetable of contents and click DisplayRoute Events.

Tip

Route identifier fieldThe Add Route Events dialog boxwill pay attention to a route layer’sroute identifier field.

Adding route events fromthe ArcMap Tools menu

1. Click Tools and click AddRoute Events.

2. Click the Route Referencedropdown arrow and clickthe route reference layer.

Alternately, click the Browsebutton and navigate to theroute reference feature class.

3. Click the Route Identifierdropdown arrow and clickthe route identifier field ifnecessary.

4. Click the Event Tabledropdown arrow and clickthe event table.

Alternately, click the Browsebutton and navigate to theevent table.

5. Click the Route Identifierdropdown arrow and clickthe route identifier.

6. Click the type of events theroute event table contains.

7. For point events, click theMeasure dropdown arrowand click the Measure field.

For line events, click theFrom-Measure dropdownarrow and click the from-measure field. Click the To-Measure dropdown arrowand click the to-measurefield.

8. Optionally, click the Offsetdropdown arrow and clickthe offset field. u

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Tip

Advanced optionsYou can have the advanceddynamic segmentation optionsapplied to subsequent ArcMapsessions by checking Apply thesesettings to all subsequent ArcMapsessions in the Advanced RouteEvents Options dialog box.

events occur at precise loca-tions along a route. Line eventsdescribe a portion of a route.

A route event table has at leasttwo fields: a route identifier andone or two measure locations.The route identifier indicatesthe route the event is locatedalong. The measure location iseither one or two valuesdescribing the positions on theroute where the event occurs.

The process of computing themap location of events stored inan event table is known asdynamic segmentation.

The result of the dynamicsegmentation process is a routeevent source, which can beused by a layer in a map. u

9. Click Advanced Options.

10. Click all of the advanceddynamic segmentations youwant applied to the routeevent source.

11. Click OK on the AdvancedRoute Events dialog box.

12. Click OK.

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Layer filesIf a layer based on route events issaved as a layer file (.lyr), thedynamic segmentation process willautomatically be performed the nexttime you add the layer to yourArcMap document.


Adding route events usingArcToolbox

1. Click the Show/HideArcToolbox button on theStandard menu to showArcToolbox.

2. Expand the LinearReferencing Tools.

3. Double-click the Make RouteEvent Layer tool.

4. Click the Input RouteFeatures dropdown arrowand click the route referencelayer.

Alternately, click the Browsebutton and navigate to theroute reference feature class.


6. Click the Input Event Tabledropdown arrow and clickthe event table.

Alternately, click the Browsebutton and navigate to theevent table.

7. Click the Route IdentifierField dropdown arrow andclick the route identifierfield. u

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The Make Route Event Layergeoprocessing tool can be usedin ArcCatalog or ArcMap. Theresult is an in-memory layer thatcan be used in other geopro-cessing operations. Oncecreated, this layer is available inthe tool dropdown menus. Ifusing ArcMap, the layer willappear in the table of contents.

For more information on in-memory layers see Geoprocess-ing in ArcGIS.

Tip

Add geoprocessing resultsto the displayIn ArcMap, if you want the resultsof the Make Route Event Layer toolautomatically added to your map’stable of contents, check Add resultsof geoprocessing operations to thedisplay, on the Geoprocessing tabof the Tools/Options dialog box.


8. Click the Event Type drop-down arrow and click thetype of event.

9. For point events, click theMeasure dropdown arrowand click the Measure field.

For line events, click theFrom-Measure dropdownarrow and click the from-measure field. Click the To-Measure dropdown arrowand click the to-measurefield.

10. Type a Layer Name for thislayer.

11. Optionally, click the OffsetField dropdown arrow andclick the offset field.

12. Click OK.

See Also

See Geoprocessing in ArcGIS formore information on ArcToolboxtools and in-memory layers.

Tip

Where is my layer?Layers created using ArcToolboxtools are in-memory layers. Youcan’t find them listed in the Catalogtree; however, they will beavailable in the appropriategeoprocessing dropdown menusfor tools. Once the program isclosed, these layers will be deletedfrom memory. Use the Save ToLayer File tool to create apermanent layer.

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105


Editing routes 6• Adding the Route Editing toolbar

• Creating routes from existing lines

• Calibrating routes with points

• Route measures

• Remeasuring routes

In addition to the display and query of routes and events, ArcMap is theapplication for creating and editing route features in your spatial database.ArcMap has tools for editing routes that are stored in shapefiles orgeodatabase feature classes.

When editing routes, it is important to remember that you are simplyediting linear features. If you already know how to edit linear features, youalready know how to edit routes. The one thing that differentiates theediting of routes from other linear features is the presence of measurevalues stored with the feature’s vertices. Hence, the editing of routefeatures can be thought of as two distinct processes. The first is theediting of the route’s geometry. The second is the editing of the route’smeasures.

This chapter shows you how to edit routes and route measures inArcMap. Route editing requires prior knowledge of editing linear featuresin ArcMap. It is assumed that you already have a good understanding ofhow to edit linear features in ArcMap. For more information, see Editingin ArcMap.



Adding the RouteEditing toolbarBefore you edit your route datain ArcMap, you need to add theRoute Editing toolbar.

1. In ArcMap, click the Viewmenu, point to Toolbars, thenclick Route Editing.

2. Click the toolbar’s title barand drag it to the ArcMapapplication window.

Tip

Adding the Route Editingtoolbar using theCustomize dialog boxFrom the ArcMap Tools menu,click Customize, click the Toolbarstab, then click Route Editing.

Tip

Adding the Route Editingtoolbar using the EditormenuFrom the Editor menu on theArcMap Editor toolbar, point toMore Editing Tools and click RouteEditing.

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Adding the Editor toolbarYou should also ensure that theEditor toolbar has been added. Todo this, click the Editor Toolbar

button on the ArcMapStandard toolbar.

EDITING ROUTES 107


Creating routesfrom existinglinesArcMap provides a variety oftools for creating linear features.Because a route is simply alinear feature with measures, ifyou are familiar with the varioustechniques for creating linearfeatures, you are already familiarwith some of the techniques forcreating routes.

The following pages outline thesteps for creating routes fromexisting line features. Thenumber of steps differs depend-ing on whether you want tocreate a simple or complex route.A complex route loops back onitself or branches.

When you create routes fromexisting lines, you must selectthe lines whose geometry youwant to copy to create the route.The selected features can befrom one or more of the linearfeature layers already in yourmap. Further, they can be fromany supported data format.

You can use any methodavailable to you to select thelinear features. For example, youcan use the Edit tool on theEditor toolbar, the SelectFeatures tool on the Toolstoolbar, Select by Attributes,and so on. u

Creating a simple route

1. On the Editor toolbar, clickStart Editing from the Editormenu.

2. Click the Task dropdownarrow and click Create NewFeature.

3. Click the Target layerdropdown arrow and click aroute layer.

4. Using any available method,select the linear feature orfeatures whose geometryyou want to copy to make theroute.

For example, click the Edittool on the Editor toolbar,move the mouse pointer overa feature, and click thefeature. Press the Shift keyand continue to click all thefeatures you want to use tocreate the route.

The selected features will behighlighted.

5. Click the Make Route buttonon the Route Editingtoolbar. u

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TipCannot see the start pointon the map

If you cannot see the start point onthe map, it may be because you arenot zoomed out far enough to seeall of the endpoints of the selectedfeatures. Note that you can interactwith other ArcMap commands andtools (e.g., Pan, Zoom Out, Zoomto Selected Features) when theMake Route dialog box isdisplayed.

Once the linear features havebeen selected, you will use theMake Route dialog box to setthe parameters for how your newroute will be created.

The first parameter you set isthe start point. This is where theroute measure values will begin.There are two ways to set thestart point. First, you can click apoint on the map. When youchoose this option, you will notethat as you move your mousearound the map, the start pointautomatically snaps to one ofthe selected feature’s endpoints.Second, you can use a coordi-nate priority of lower left, lowerright, upper left, or upper right.These coordinate priorities aredetermined using the minimumbounding rectangle around theselected set of linear features.The endpoint from the selectedfeatures that is closest to thechosen coordinate priority willbe where the measures start. u


7. Move your mouse over theselected linear features andclick the map when the startpoint is where you want theroute measures to start.

8. Click the option for how youwant the route measurevalues to be obtained.

9. Adjust the Multiply measuresby and Start measure valuesif necessary.

10. Click Make Route.

The newly created route isnow selected.

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EDITING ROUTES 109

ArcInfo and ArcEditorThe next parameter you setindicates how the measurevalues are to be obtained. Whenyou choose the geometric lengthoption, it is important to realizethat the geometric length of eachselected feature is determined inthe units of the target layer’scoordinate system and notnecessarily the feature’s nativecoordinate system. This is toaccount for the fact that within asingle data frame, features withdifferent coordinate systems canbe projected on the fly.

The measure field option is onlyenabled when all the selectedlinear features are from the samelayer. Measure values on thenew route will be accumulatedusing the values in this field.

Use the From/To option whenyou know the start and endmeasure values for the newroute. All measure valuesbetween the start and end will beinterpolated for you.

Multiplying measures is usefulwhen you want to convertbetween measure units. Forexample, your route data isstored in a feature class withcoordinate system units in feet.You want the measures on yourroutes to be in miles. You wouldmultiply your measures by0.0001893994 to convert fromfeet to miles. The measuremultiplication factor is applied u

Creating a complex(looping) route

1. Click the Task dropdownarrow and click Create NewFeature.

2. Click the Target layerdropdown arrow and click aroute layer.

3. Using any available method,select a simple chain oflinear features that do notform a loop.

For example, click the Edittool on the Editor toolbar,move the mouse pointer overa feature, and click thefeature. Press the Shift keyand continue to click all thefeatures you want to use tocreate the route.

The selected features will behighlighted.


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7. Click the option for how youwant the route measurevalues to be obtained.



9. Using any available method,select a simple chain oflinear features that form thesecond half of the loop.


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TipCoordinates or measuresout of bounds

If you get the Coordinates ormeasures out of bounds messagewhen creating a route, it is becausethe measure values that are beingapplied to the new route do not fitin the m domain. For moreinformation, see Chapter 4,‘Creating Route data’.

before the selected lines aremerged to create a route.

The Start measure option isuseful when you want your newroute to have a start measureother than 0.

The last parameter you setindicates whether or not youwant the measures to becontinuous on disjointedroutes. Note that if you chooseto have noncontinuousmeasures, the gap distance iscalculated using the units of thetarget layer’s coordinatesystem. This might causeunexpected measure values, forexample, when you use a fieldthat stores mileage values toaccumulate the measure and thetarget layer’s coordinate systemunits are meters. Note that thischeck box is not available whenthe From/To option has beenchosen to set the measures.

Once the new route has beencreated in the target feature u

EDITING ROUTES 111

ArcInfo and ArcEditor11. Click the Start Point button.


13. Click how you want theroute measure values to beobtained.



15. Using any available method,select the two routes that willform the loop. u

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class, the selected set of inputlinear features will becomeunselected, and the new routewill become selected. This is sothat you can set its attributes,such as the route identifier. Formore information on editingattributes, see Editing inArcMap.

The process of creating acomplex route is similar to thatof creating a simple route. Theonly real difference is that youmust build a complex route inpieces. Once the pieces arecreated, they can be mergedtogether.

The work flow shown here forcreating a complex (looping)route is not the only one. Withyour knowledge of editing inArcMap, you may choose awork flow that is more appropri-ate for your organization.

Take note of the fact that in thecomplex route example shownhere, care has been taken to setthe measures appropriately foreach of the two halves of theroute that will eventually bemerged together. If this is notpossible in your situation, youcan still merge the piecestogether. Then at a later time,the measure values can bereset. For more information, see‘Remeasuring routes’ in thischapter.



16. Click the Editor menu andclick Merge.

17. Click OK.

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Preserving overlappingsegmentsThe Preserve overlappingsegments check box only appearswhen you are merging two routes.Make sure this box is checked (thedefault) when you are creating alooping route.

Tip

Setting the selectablelayersSometimes, when editing, it iseasier to edit particular layers bymaking other layers unselectable.You can set the selectable layersthrough the Selection menu or inthe Selection tab. To learn more,see Using ArcMap.

EDITING ROUTES 113


Calibratingroutes withpointsIt is important to have accuratemeasure values along routes,especially when the measuresare used to tie in large amountsof event data.

It is possible to adjust routemeasures to correspond withknown measure locations witha procedure called calibration.Calibration adjusts routemeasures using points. A routecan be successfully calibratedwith two or more points.

Once you have selected theroute that you want to cali-brate, you must digitize thepoints to use for calibration. Todigitize the points, you use theSketch tool. Optionally, youcan set the snapping environ-ment. For example, you mightwant to snap to points that arestored in another feature class.Because one route is calibratedat a time, there is no point-to-route cutoff tolerance speci-fied. All digitized points will beassumed to fall on top of theselected route. u

1. Click the Task dropdownarrow and click CalibrateRoute Feature.

2. Click the Edit tool, move themouse pointer over a routefeature, then click thefeature.

3. Click the Calibrate Routebutton on the Route Editingtoolbar.

The Calibrate Route dialogbox will appear.

4. Click the Sketch tool on theEditor toolbar.

5. Click the map at eachlocation along the route,where you want a calibrationpoint.

You will see the CalibrateRoute point list beingpopulated in the dialog boxas you click the points. u

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Tip

UndoIf you digitize a point you do not

like, click the Undo buttonon the ArcMap Standard toolbar.



6. Type the new measure valuefor each clicked point.

7. Click the calibration optionsyou would like.

8. Click Calibrate Route.

Once all the calibration pointshave been digitized, you mustthen type the new measurevalue for each point.

Either whole or partial routescan be calibrated. You canchoose to interpolate betweenthe calibration points, extrapo-late before the calibrationpoints, extrapolate after thecalibration points, or use anycombination of these methods.

In order for the measure valueon a vertex to be interpolatedor extrapolated, a calibrationratio is needed. There are twoways this ratio can be deter-mined. The first method usesthe shortest path distancebetween the input points. Thesecond method uses theexisting measure distancebetween the input points.

When calibrating disjointedroutes, you may choose toignore the distance of thespatial gap between the parts.If you choose to ignore spatialgaps, route measures will becontinuous. If you want thespatial gap incorporated in themeasures, the gap distance isthe straight-line distancebetween the endpoints of theparts.

Tip

Order is importantMake sure you digitize thecalibration points in either routeincreasing or decreasing order,rather than in some random order.

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EDITING ROUTES 115


Route measures

Editing existing routes

Whenever a route’s geometry is edited in ArcMap, its measurevalues are edited as well. Because of this, there are three rulesthat are followed whenever a route’s geometry is changed.

First, the measure value on newly added vertices is interpolatedwhen the new vertex falls between two vertices with knownmeasure values.

A new vertex will have its measure value interpolated only when it iscreated between two vertices that have known measure values.

0

1

2

3

0

1

2

31.5

0

NaN

2

3

0 2

3NaNNaN

Case A Case B

0

1

2

3

0

1

2

3

NaN

NaN

A new vertex will not have its measure value extrapolated when a route isextended.

0

5

15

20

32

1 0

Intersect7.5

12.5

2

1- or -

When geometries overlap, some editing commands must choose which ofthe input feature’s measures will be used for the output. In these cases, themeasures from the feature that was selected first will be used. In thisintersect example, both possible results are shown.

40m

0 10 20 30 40

Set measures as the distance from the route’s origin.

Second, in cases where a route’s geometry has been extended,newly added vertices will not have their measure valueextrapolated.

Finally, certain editing commands, such as Merge, Union, andIntersect, take two or more input geometries and produce anoutput geometry. In some cases, these commands will encountersituations where the input geometries overlap. Consequently,these commands must choose which of the input feature’smeasures to use in the output. In such cases, the measure valuesfrom the feature that was selected first will be used.

Setting route measures

The following methods can be used to set a route’s measurevalues. It is possible to apply all of these methods to whole orpartial routes.

Set As Distance—Set the route’s measure values to be thecumulative length from the origin of the geometry. Hence, routemeasures will increase with the digitized direction of the route.



5 15 25 35 45

0 10 20 30 40

Offset route measures by 5.

0 10 20 30 40

0 NaN NaN 30 NaN

Interpolate or extrapolate unknown measure values.

NaN

0 10 20 30 40

NaN NaN NaN NaN

Set all route measures to NaN.

0 10 20 30 40

0 10 20 30 40

Set a route’s digitized direction to match the direction of the measures.

Set From/To—Set the route’s measures using known start andend values. All measure values between the start and end will beinterpolated.

In some applications, the ratio between a route’s length and itsmeasures is not constant. When the Set From/To method isapplied to a route, it is possible to preserve the measure schemathat exists. That is, this method can assign measure values basedon the original measure value.

Sometimes a constant change needs to be applied to a route’smeasures. This is the case whenever measures need to berescaled or converted into different units or simply incrementedby some value. You can meet these needs by using the next twomethods.

Apply Factor—Multiply a route’s measures by a factor.

Set the start measure to be 0 and the end measure to be 100. All measurevalues in between are interpolated.

0 25 50 75 100

0 2 4.5 7 10

0 20 45 70 100

Do not preserve existing measureschema

Preserve existing measure schema

0 25 50 75 100

0 2.5 5.0 7.5 10.0

Multiply route measures by a factor of 10.

Offset—Add a value to a route’s measures.

Calculate NaN—Interpolate or extrapolate all route measures thatare unknown (NaN).

Drop Measures—Set all route measures to NaN.

Set Direction As M—There is no requirement that a route’smeasures increase with the digitized direction. This method willflip a route’s geometry to match the direction in which themeasures are increasing.

EDITING ROUTES 117


RemeasuringroutesRoute measures need to beedited, for example, when moreaccurate information has beenobtained or when the geometryof the route has been altered insome way.

Route measures are edited viaan edit sketch. When editingroute measures, the edit sketchis simply a shape that repre-sents a copy of the route’sgeometry. Once you have madethe necessary changes to theroute measures, you finish theedit sketch. Finishing thesketch writes the sketchgeometry to route. u

Setting measures asdistance

1. Click the Task dropdownarrow and click ModifyFeature.

2. Click the Edit tool, move themouse pointer over the routefeature you want toremeasure, then click thefeature.

A copy of the selected route’sgeometry is written to the editsketch.

3. Right-click the edit sketch,point to Route MeasureEditing, then click Set AsDistance.

4. Type the starting measurevalue and press Enter.

At this point, the changes tothe measures have beenapplied to the sketch only. Tofinish the sketch, press F2 orsimply unselect the routefeature.

Tip

Double-clicking to modify afeatureWhen the Edit tool is selected, youcan double-click a feature whenyou want to modify it. The edit taskwill automatically change to ModifyFeature.

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Edit Sketch PropertiesBecause route measures are set onan edit sketch, open the Edit SketchProperties dialog box if youwant to see the changes as theyhappen.



Setting from/to measures

1. Click the Task dropdownarrow and click ModifyFeature.


A copy of the selected route’sgeometry is written to the editsketch.

3. Right-click the edit sketch,point to Route MeasureEditing, then click Set From/To.

4. Type the from and to mea-sure values, click whetheryou want to preserve theexisting measure schema,then press Enter.

At this point, the changes tothe measures have beenapplied to the sketch only. Tofinish the sketch, press F2 orsimply unselect the routefeature.

Realigning a route is the act ofdefining a new course for aroute. Once a route is realigned,you may need some portions ofthe route measures to remainunchanged, while otherportions need to be updated.Because of this need, it ispossible to remeasure wholeroutes or portions of routes. u

Tip

Using the Route MeasureEditing options multipletimesThere are many situations in whichyou may need to use the RouteMeasure Editing options more thanonce to achieve the desired result.For example, you may want theroute measures on a new route tobe stored in miles. The routefeature class, however, has beendigitized in feet. An easy solution tothis is to first use the Set AsDistance option to set the measuresin feet. Then the Apply Factoroption could be used to convertfrom feet to miles (the factor wouldbe 0.00018939394).

TipCoordinates or measuresout of bounds

If you get the Coordinates ormeasures out of bounds messagewhen remeasuring a route, it isbecause the measure values thatare being applied to the route donot fit in the m domain.

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EDITING ROUTES 119


Remeasuring a portion ofa route

1. Click the Task dropdownarrow and click ModifyPortion of a Line.


3. Click the Define Line Portionbutton.

4. Click a point along theselected route to startdefining the portion.

5. Click a second point alongthe selected route to finishdefining the portion.

An edit sketch is created.

6. Right-click the edit sketch,point to Route MeasureEditing, then click the optionyou want to use toremeasure the portion.

7. After making your changes tothe sketch, you need to finishthe sketch. To finish thesketch, press F2 or simplyunselect the route feature.

When you are defining aportion of a route to beremeasured, you are actuallycreating a sketch whosegeometry represents just thedefined portion. Once thesketch has been created, youuse the Route Measure Editingsketch menu—just like youwould if you were remeasuringthe entire route.

Tip

Number of decimalsThe number of decimals displayedwhen defining the subportion of aroute corresponds to the number ofdecimals setting on the General tabof the Editing Options dialog box.

Tip

Map Tip textWhen defining a portion of a routeto be remeasured, the text of theMap Tip corresponds to themeasure value at that point alongthe selected route.

Tip

Context menuWhen you are defininga portion of a route,you can right-click themap to display acontext menu. Theoptions on this menuallow you to quicklymove to any pointalong the route.

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IN THIS CHAPTER

121

Creating and editing event data 7• Creating and editing event data

• Creating event tables in ArcCatalog

• Overlaying events

• Aggregating events

• Transforming event measures

• Locating features along routes

• Editing event tables in ArcMap

An event table is just like any other table in ArcGIS Desktop; it is adatabase component that contains a series of rows and columns. In an eventtable, each row describes a location along a route, and each columnrepresents a particular attribute about the route location. Event tables arestored in any supported format—for example, INFO, Microsoft Access,dBASE, Oracle®, SQL Server™, delimited text files, and databasesaccessed via OLE DB providers.

In this chapter, you will learn how to create and edit event data and tables.However, before you start creating and editing event data, note that manyorganizations already maintain large event databases. Quite often, thesedatabases can be accessed and their tables can be used as events withoutany modification. Any table that contains route identifier and route measurefields—the route location fields—can be used as an event table.

Event tables are generally created in ArcCatalog. Once created, ArcMapmakes it easy to view and update the attributes of the events in yourdatabase.


ArcInfo

Creating and editing event data

Creating event data

In order to be used as an event table, a table must contain routelocation fields, which are used to find the location of the eventsalong routes.

Event tables can be created in ArcCatalog, where there are toolsfor creating geodatabase, dBASE, and INFO tables.

Event data can be stored in any supported table. Shown here aregeodatabase, text file, INFO, and dBASE tables.

geodatabase

text file

INFO

dBASE

There are some additional techniques that automate the task ofevent table creation:

• Creating point events by locating point features along routes

• Creating line events by locating polygon features alongroutes

• Create line events by locating lines along routes

• Overlaying existing event data to create new line or pointevents

• Aggregating existing event data using concatenate anddissolve operations

• Transforming route measures from one route reference toanother

Overlaying events

In ArcMap, geographic data is represented on a map as a layer.When event data has been added to a map in the form of a layer(see ‘Adding route events’ in Chapter 5), it can be queriedaccording to feature locations and attributes to solve problems.Further, new spatial relationships can be discovered by askingquestions such as Where is...? Where is the closest...? and Whatintersects...? For more information on how to find answers tothese types of questions, see Using ArcMap.

Overlaying events is another way to create new event data. Thisprocess combines two input event tables to create a single outputevent table. The new table can be used to analyze event data inways not possible using traditional spatial analysis techniques.

The new event table can contain either the intersection or theunion of the input events. The union of the input events splits alllinear events at their intersections and writes them to the newevent table. The intersection of the input event tables writes onlyoverlapping events to the output event table.

Line-on-line, line-on-point (same as point-on-line), and evenpoint-on-point event overlays can be performed.

Line-on-line overlay

A line-on-line overlay involves the overlay of two line eventtables to produce a single line event table.

CREATING AND EDITING EVENT DATA 123

ArcInfo

0.0 10.0 20.0 30.0 40.0 50.0Line-on-line overlay

Input table

Overlay table

Union

Intersect

AB

AABB

BA

A/AAB/AA

A/BBA

A/AAB/AA

A/BB

B/BB

Line-on-point overlay

Input table

Overlay table

Union

Intersect

0.0 10.0 20.0 30.0 40.0 50.0A

B

AA BB

BB

AC

C

C

CC

B/AA A/BB A/CCB/BB C/CC

B/AAA/BBB/BB

A/CCC/CC

The example below shows the union of a line event table thatstores pavement information and another line event table thatstores pavement resurfacing dates. The result can be used, forexample, to find the characteristics of the oldest paved sections.

Line-on-point overlay

A line-on-point overlay involves the overlay of a line event tableand a point event table. The process produces a single pointevent table.

The example below shows the intersection of a point event tablecontaining accident locations and a line event table containingpavement information. The result can be used, for example, toanalyze pavement characteristics where accidents occurred.

23.5 44.244.284.7167.4182.8

167.4182.8209.5

5030809545

CRACKTMP

101101101101101RID FMP

84.7

45

3.2 21.123.544.284.721.195.5

167.4

84.795.523.5167.4182.8

05030800

8095

2/5/859/3/879/3/879/3/879/3/874/28/614/28/61

RESURFCRACKTMP

101101101101101101101RID FMP

44.2

101 182.8 190 4/28/61

23.5 44.244.284.7

167.4167.4182.8

2/5/859/3/87

4/28/611/21/74

RESURFTMP

101101101101RID FMP

84.7

Unioning two event tables can help expose spatial relationships not evidentbefore the overlay. Here, two line event tables are unioned. The outputevent table contains all of the input events, which have been split wherethey intersected.

23.5 44.244.284.7167.4182.8

167.4182.8209.5

5030809545

CRACKTMP

101101101101101RID FMP

84.725.9 295.6

172.3180.3

13

0101

ALCINJ

101101101101RID MILE

1

25.9 295.6172.3180.3

13

0101

50809595

CRACKALCINJ

101101101101RID MILE

1

Intersecting two event tables can help expose spatial relationships notevident before the overlay. Here, a line and a point event table have beenintersected.


ArcInfo

Aggregating event data

You aggregate existing event data using concatenate anddissolve operations. These operations are designed to helpmaintain the integrity of large event tables.

Both the concatenate and dissolve operations combine eventrecords in tables where there are events on the same route andthey have the same value for specified fields. The result is writtento a new event table. One difference between the two operationsis that concatenate will only combine events in situations wherethe to-measure of one event matches the from-measure of the nextevent. Dissolve will combine events when there is measureoverlap. Another difference is that the dissolve operation isavailable for both line and point event tables, while theconcatenate operation is available only on line event tables.

You can use concatenate or dissolve to remove redundantinformation from an event table. For example, if one linear event ina pavement event table has an attribute—concrete—from 0 to100, and the following event record has an attribute—concrete—from 100 to 125, the two events will be merged into a single eventfrom 0 to 125. Getting rid of redundant event information makes allsubsequent operations on the events more efficient.

Another use for concatenate or dissolve is to break up eventtables having more than one descriptive attribute into separatetables. For example, if a pavement event table has fields LANESand MATERIAL, the event table can be subdivided into twotables: one having the attribute LANES, and the other having theattribute MATERIAL. To do this, the dissolve or concatenateprocess would need to be run twice.

Dissolve

Concatenate

Input table

0.0 10.0 20.0 30.0 40.0 50.0

Concatenating and dissolving events

AA

AA

A

A

AA

A

Concatenating and dissolving events combine adjacent records in linearevent tables if they are on the same route and have the same values forthe dissolve field or fields.

1 01111

125175205

100125175205215

concreteconcreteasphaltasphalt

concrete

MATERIALTMPFMPRID

100 1 011 205

125205215

concreteasphalt

concrete

MATERIALTMPFMPRID

125

Concatenating or dissolving events can be used to remove redundantinformation from event tables.

0 15150

12516535

125165210155

224242

concreteasphaltasphalt

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MATERIALLANESTMP

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12516535

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32221

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concreteasphalt

MATERIALTMP

32211

RID FMP

90

Concatenating or dissolving events can also be used to break up eventtables with multiple descriptive attributes.


ArcInfo

Transforming event measures

In certain circumstances, it may become necessary to update themeasure values in an event table. For example:

• Using an event table to reference multiple route references,each of which has its own unit of measure

• Keeping measures up to date when a route is recalibrated orrealigned

Use with multiple route references

In many agencies, event data is collected against multiple routereference systems. For example, a DOT might use both a referencemarker system and a milepost system. Some event data, such asaccident locations and maintenance activities, is recorded usingthe reference marker system, while other event data, such aspavement condition or capital improvement projects, is recordedusing the milepost system of measurement.

Every year, a DOT manager is required to determine whichsections of highway need to be resurfaced. Using a pavementevent table, a manager could determine which segments ofpavement have fallen into ill repair. The manager does not,however, want to resurface highways with certain types ofaccident histories without first performing a safetyanalysis. The reason for this is that speeds may increase on thenew pavement, which could increase the accident rate evenfurther.

In order to make a well-informed decision, it will be necessary tocombine and analyze the event data that has been collectedagainst the different route references. The pavement scores arebased on milepost values, while the accident data is based onreference marker system. To combine the event data, thepavement events must be transformed to the reference marker

system, or the accident events must be transformed to themilepost system.

In most cases, you will use the ArcToolbox Transform RouteEvents tool to transform events from one route reference toanother. This tool calculates the x,y coordinate location of eachevent in an input route reference and matches this to thecorresponding measure values in a second route reference. Thestructure of the routes need not be the same. A new event table iswritten out with the events encoded in a different system ofmeasures.

In cases in which route structure is identical and the difference inmeasures between two reference systems is constant, a simplemathematical equation can be used to transform event measures.For example, if one route reference has its measures in miles andthe other has its measures in feet, then all that needs to be doneis to multiply the miles by 5,280 in the field calculator to obtainfeet.

Keeping event measures up to date

Measure locations tie an event to a particular location along aroute. When the measures of a route are altered, the events willno longer be mapped to the same position along their routes.

0.2 0.40.41.6 2.4

fairgoodpoor

ConditionTMP

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ConditionTMP

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It is necessary to transform events to analyze events recorded using oneroute reference with events recorded using another route reference.


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In some cases, this is the desired result. For example, if themeasures along a stream need calibration to match up to knownmileages at gauging stations and the location of fish habitatevent data was collected using the gauging stations, thennothing needs to be done to the event data when the routemeasures are altered.

In other cases, the location of the events when they are mappedmust be maintained. For example, if a highway is realigned, themeasure of events describing the location of road signs must beupdated to maintain their original positions.

If changes in route measures are linear along the length of aroute, an equation can be applied to the event measures. Forexample, if a route’s measures are multiplied by a factor of 1,000 toconvert from kilometers to meters, all event measures can also bemultiplied by 1,000.

If changes in route measures are nonlinear, such as what happensduring a realignment procedure, then the Transform Route Eventstool can be used to recalculate the measures in an event table tomaintain the real-world locations.

Locating point features along routes

When you locate point features along routes, you aredetermining the route and measure information of where yourpoint data intersects your route data.

Locating point features along routes is useful, for example, whenyou need to locate:

• Signs along highways

• Wells or gauging stations along river reaches

• Stops along bus routes

• Manholes along city streets

• Valves along pipes

50% original length

50% edited length

Realigning a route causes measure values to change. Events located onthis route will no longer be in the same position.

A101 0A101A101A101A101A101

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Point_ID Route_ID

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A101

Locating points along routes creates a new point event table containing theroute identifier and measure information of where points intersect routes.


ArcInfo

Locating polygon features along routes

Locating polygon features along routes computes the route andmeasure information at the geometric intersection of polygon dataand route data. Once polygon data has been located alongroutes, the resulting event table can be used, for example, tocalculate the length of route that traveled through each polygon.

Locating polygon features along routes is useful, for example,when you need to locate:

• Soils, spillways, areas of inundation, or hazard zones alongriver reaches

• Wetlands, hazard zones, or town boundaries along highways

Locating line features along routes

When you locate line features along a route, you are determiningthe route and measure information where the lines intersect withthe route. This intersection is based on a specified clustertolerance.

Locating line features along routes is useful, for example, whenyou need to tie them in with your linearly referenced data.

Editing event data

Event tables are only as good as the information they contain.Over time, you will need to modify event data to keep it accurateand up to date. ArcMap lets you edit event data. You can edit anyof the attribute values in an event table as well as add and deleteevent records. You can also use the field calculator to change theattribute value of a field for several events at once.

Locating polygon data along routes computes the geometric intersection ofthe route and polygon data.

A101 5A101A101 24

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Locating line features along routes creates a line event table.

0 40

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Creating eventtables inArcCatalogYou can create geodatabase,dBASE, and INFO event tablesin ArcCatalog with easy-to-usetable designers.

For a table to be considered anevent table, it must contain theappropriate route locationfields. For point event tables,the required fields are a routeidentifier field and a measurefield. For line events, therequired fields are a routeidentifier field plus both a from-and a to-measure field. All otherfields define each point or lineevent’s attribute information. u

Creating a table in ageodatabase

1. Right-click the database inthe Catalog tree in which youwant to create a new table,point to New, then clickTable.

2. Type a name for the table. Tocreate an alias for this table,type the alias.

3. Click Next. u

See Also

For more information aboutcreating a table in a geodatabase,see Building a Geodatabase.

Tip

Route location fieldsThe route identifier field can be anynumeric or character data type.You should consider creating anattribute index on the routeidentifier field; it will help improvedynamic segmentation perfor-mance. The measure field or fieldsmust be a numeric data type.

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For more information aboutconfiguration keywords withArcSDE, see the ArcSDE Configu-ration and Tuning Guide for<DBMS> PDF file.

Tip

OBJECTID field in ageodatabase tableThe OBJECTID field in a geodata-base table uniquely identifies eachobject stored in the table. It cannotbe deleted.

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When defining an event table’sname and fields, be aware thateach database has its own rulesdefining what names andcharacters are permitted. Referto your database’s documenta-tion for a list of these rules.

For dBASE tables, the processof defining the attributes isseparate from creating the tableitself. After creating the table,you need to right-click it in theCatalog tree and click Propertiesto define the attributes.Because they must contain atleast one field, the text fieldName1 is added. Add theappropriate fields to the dBASEtable, then delete the defaultfield. In a dBASE table, a fieldname must be 10 characters orless; additional characters willbe truncated. u

If your table does not useArcSDE, skip to step 5.

4. Click Use configurationkeyword and type thekeyword if you want to createa table using a customstorage keyword.

5. Click Next.

6. Click the next blank row inthe Field Name column andtype in a name to add a fieldto the table.

7. Click in the Data Typecolumn next to the new field’sname and click its data type.

8. Click the field next to Aliasand type the alias name tocreate an alias for this field.

9. Click the field next to AllowNULL values and click No toprevent nulls from beingstored in this field.

10. Click the field next to DefaultValue and type the value toassociate a default valuewith this field.

11. Click the field next toDomain and click thedomain to associate adomain with this field.

12. Repeat steps 6 through 11until all the table’s fieldshave been defined.

13. Click Finish.

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Creating a dBASE table

1. Right-click the folder in theCatalog tree in which youwant to create the new table,point to New, then clickdBASE Table.

A new dBASE table appearsin the folder’s contents.

2. Type the name for the tableand press Enter.

3. To add a field to the table,right-click the table in theCatalog and click Properties.

4. Click the Fields tab.

5. Click the next blank row inthe Field Name column andtype in a name.

6. Click in the Data Typecolumn next to the newfield’s name and click its datatype.

7. Click in the Field Propertieslist and type the propertiesfor the new field.

8. Repeat steps 5 through 7until all the table’s fieldshave been defined.

9. Click OK.See Also

For more information aboutcreating a dBASE table, see UsingArcCatalog.

Tip

OID field in a dBASE tableThe OID field in a dBASE table is avirtual field that is created byArcGIS when the table’s contentsare accessed. It is used to ensurethat each object in the table has atleast one unique value. It cannot bedeleted.

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An INFO table’s name must be32 characters or less, and theitem names must be 16 charac-ters or less. Items are definedusing standard ArcInfo datatypes. The input width is themaximum number of charactersor bytes used to store the item’svalues. For numeric items, thewidth must be large enough toaccommodate the decimal pointand negative sign. The displaywidth is the number of spacesused to display values inArcInfo Workstation; fordecimal values, the displaywidth should be one spacegreater than the input width toaccount for the decimal point.

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Creating an INFO table

1. Right-click the folder in theCatalog tree in which youwant to create the new table,point to New, then click INFOtable.

2. Type a name for the newtable.

3. Click the data type of the firstitem in the table.

4. Type the name for the newitem.

5. Change the column width,display width, and decimalplaces as necessary.

6. Click New item to addanother item to the table.Then repeat steps 3 through5 to define the new item’sproperties.

7. Repeat step 6 until all itemshave been added to thetable.

8. Click OK.

See Also

For more information aboutcreating an INFO table, see UsingArcCatalog.

Tip

Creating a new workspaceAll INFO files must reside withinan INFO workspace. To create anew workspace, right-click thefolder where the workspace willreside in the Catalog tree, point toNew, then click ArcInfo Workspace.

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Overlaying eventsThe Overlay Route Events toolin ArcToolbox can be used tooverlay event tables. Line-on-line, line-on-point, and evenpoint-on-point event overlayscan be performed.

To successfully overlay theinput event table and overlayevent table, both should bebased on the same routereference. Otherwise, you mayget erroneous results.

The output event table cancontain either the intersectionor the union of the inputevents. The union of the inputevents splits all linear events attheir intersections and writesthem to the new event table.The intersection of the inputevent tables writes onlyoverlapping events to theoutput event table.

If either of the input tablescontains point events, theoutput will always be a pointevent table. u

Intersecting or unioningoverlaying events



3. Double-click the OverlayRoute Events tool.

4. Click the Input Event TableBrowse button and navigateto the input event table.

Alternately, click the InputEvent Table dropdown arrowand click the input eventtable or layer.

NOTE: In ArcCatalog, you willonly see a dropdown arrow ifan in-memory layer has beencreated during the session.


6. Click the Event Type drop-down arrow and click POINTor LINE. u

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Properties that are definedautomaticallyIf you select a layer for either theInput Event Table or Overlay EventTable, the Input Event TableProperties and Overlay EventTable Properties will be setautomatically.

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Tip

Adding the route eventtable as a layerYou can add a route event table toyour map as a layer using eitherthe Make Route Event Layer tool orthe Add Route Events dialog box inArcMap.

The new event table can bewritten to the workspace ofyour choice.

By default, the output eventtable contains a route identifierfield, the measure fields, plus allof the input event attributes.You can choose to not write outthe event attributes. In thiscase, only the respective eventlayer’s OBJECTID field will bewritten to the output table. Thisfield can be used at a later timeto join or relate back to theoriginal event attributes.

When both inputs are lineevent tables, you can specifywhether you want to keep zerolength line events in the outputtable. These are events wherethe from- and to-measures areequal and can be created by theoverlay process.


Depending on whether youroutput is a point or line eventtable, you may choose aMeasure Field or a From-and To-Measure Field.

8. Click the Overlay Event TableBrowse button and navigateto the input event table.

Alternately, click the OverlayEvent Table dropdown arrowand click the input eventtable or layer.


10. Click the Event Type drop-down arrow and click POINTor LINE.


12. Click the Type of Overlaydropdown arrow and clickeither INTERSECT orUNION.

13. Type the Output Event Tablefilename and path or clickthe Browse button to specifythe output location. u

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14. Default Output Event TableProperties will be set for you.You may change thesuggested field names byclicking any of the activedropdown arrows andselecting an alternativevalue.

15. Click OK.

Tip

Using the ArcMap RouteEvents GeoprocessingWizardYou can add the Route EventsGeoprocessing Wizard to anArcMap menu. You can find it in theTools, Customize dialog box, on theCommands tab, contained in theLinear Referencing category. Tolearn about customization inArcMap, see Using ArcMap.

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ArcInfo

AggregatingeventsYou can use the Dissolve RouteEvents tool, in ArcToolbox, toaggregate event data. This toolwill combine events that haveoverlapping measures. Use thistool to remove redundantinformation from event tables orto break up event tables havingmore than one descriptiveattribute into separate tables.The result will be written to anew event table in theworkspace of your choice.

You can dissolve on one ormore fields.

Dissolving route events



3. Double-click the DissolveRoute Events tool.

4. Click the Input Event TableBrowse button and navigateto the input event table.

Alternately, click the InputEvent Table dropdown arrowand click the input eventtable.


6. Click the Event Type drop-down arrow and click eitherPOINT or LINE.


For line events, click theFrom-Measure Field drop-down arrow and click thefrom-measure field. Click theTo-Measure Field dropdownarrow and click the to-measure field.

8. Click one or more DissolveFields. u

Tip

Using the ArcMap RouteEvents GeoprocessingWizard to dissolve orconcatenate eventsYou can add the Route EventsGeoprocessing Wizard to anArcMap menu. You can find it in theTools, Customize dialog box, on theCommands tab, contained in theLinear Referencing category. Tolearn about customization inArcMap, see Using ArcMap.

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9. Type the Output Event Tablefilename and path or click theBrowse button to specify theoutput location.

10. Default Output Event TableProperties will be set for you.You may change thesuggested field names byclicking any of the activedropdown arrows andselecting alternative values.

11. Optionally, click Combineadjacent events only.

12. Click OK.

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Transformingevent measuresThere are two ways you cantransform event measures. First,in ArcMap, if the requiredtransformation is constant, youcan use the field calculator. Forexample, you can use the fieldcalculator to easily transformevent measures between feetand miles.

Second, you can use theTransform Route Events tool totransform one route reference toanother. This output will be anew event table.

To be transformed successfully,the input events must be withina specified tolerance of theroutes in the target routereference. The default searchtolerance is 0. u

Transforming eventmeasures using the fieldcalculator

1. In ArcMap, click the Editormenu on the Editor toolbarand click Start Editing if youhave not already started anedit session.

2. Right-click the table youwant to edit in the table ofcontents and choose Open.

3. Select the records you wantto update. If you don’t selectany, calculations will beapplied to all records.

4. Right-click the field headingfor which you want to make acalculation and clickCalculate Values.

5. Use the Fields list andFunctions list to build acalculation expression. Youcan also edit the expressionin the text area below. Lastly,you can type in a value to setthe field to.

6. Click OK.

Tip

Calculating fields outsidean edit sessionYou can calculate field valuesoutside an edit session. You cannot,however, undo your changes.

See Also

For more information on fieldcalculations, see Using ArcMap.

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Transforming routeevents



3. Double-click the TransformRoute Events tool.

4. Click the Input Event TableBrowse button and navigateto the input event table orlayer.

Alternately, click the InputEvent Table dropdown arrowand click the input eventtable or layer.


6. Click the Event Type drop-down arrow and click POINTor LINE.


For line events, click theFrom-Measure Field drop-down arrow and click thefrom-measure field. Click theTo-Measure Field dropdownarrow and click the to-measure field. u

Tip

Route structureWhen transforming events, theinput route structure and targetroute structure need not be thesame.

Tip

Choosing a toleranceAlways use a small tolerance. Thelarger the tolerance specified, thegreater the chance of erroneousresults.

The output event table containsall of the input event table’sattributes, but the routeidentifier and measure locationinformation are from the targetroute reference.

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8. Click the Source RouteFeatures Browse button andnavigate to the source routefeature class.

Alternately, click the SourceRoute Features dropdownarrow and click the sourceroute feature class.

9. Click the Source RouteIdentifier Field dropdownarrow and click the sourceroute identifier field.

10. Click the Target RouteFeatures dropdown arrow orBrowse button to select thetarget route feature class.

11. Click the Target RouteIdentifier Field dropdownarrow and click the targetroute identifier field.

12. Type the Output Event Tablefilename and path or clickthe Browse button to specifythe output location.


14. Optionally, type a ClusterTolerance, then click thedropdown arrow and click aunit of measure.

15. Click OK.

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Using the ArcMap RouteEvents GeoprocessingWizard to transform eventmeasuresYou can add the Route EventsGeoprocessing Wizard to anArcMap menu. You can find it in theTools, Customize dialog box, on theCommands tab, contained in theLinear Referencing category. Tolearn about customization inArcMap, see Using ArcMap.


ArcInfo

Locating featuresalong routesYou can locate point, line, orpolygon features along routesusing the Locate FeaturesAlong Routes tool.

When locating point featuresalong routes, the route andmeasure information of eachpoint feature is computed andwritten to a point event table.When locating line featuresalong routes, the route andmeasure information is com-puted at the intersection of theline and route data and writtento a line event table. Whenlocating polygon features alongroutes, this route and measureinformation is computed at thegeometric intersection ofpolygon data and route dataand written to a line eventtable.

To be located successfully, thefeatures must be located on orwithin a specified tolerance ofthe routes. The default searchtolerance is 0. You control thesize of the search tolerance byspecifying a distance inwhichever units you prefer. Thesearch tolerance for pointsspecifies a search radius andfor lines it specifies a clustertolerance. The search tolerancedoes not apply to polygons. u


2. Expand the Linear Refer-encing Tools.

3. Double-click the LocateFeatures Along Routes tool.

4. Click the Input FeaturesBrowse button and navigateto the feature class or layer.

Alternately, click the drop-down arrow and select theinput layer.

5. Click the Input RouteFeatures Browse button andnavigate to the feature classor layer.

Alternately, click the drop-down arrow and select theinput layer.


7. If the input is a point featureclass, type a search radius.

If the input is a line featureclass, type a cluster toler-ance.

If the input is a polygonfeature class, the parameteris disabled.

8. Click the Search Radiusdropdown arrow and click aunit of measure. u

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By default, the output eventtable contains the routeidentifier and the measurelocations; plus all of theattributes from the input featureclass.

You can choose to not write outthe feature’s attributes. In thiscase only the feature’sOBJECTID field will be writtento the output table. This fieldcan be used at a later time tojoin or relate back to theoriginal point attributes.

9. Type the Output Event Tablefilename and path or click theBrowse button to specify theoutput location.


11. Click OK.

Tip

What is a zero length lineevent?A zero length line event occurswhen the from- and to-measuresare the same. This can happen inlocating polygons along routes, forexample, when a polygon touches aroute but does not overlap it.

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Editing eventtables in ArcMapYou can edit event attributes intwo ways: using the event’sattribute table or using theAttributes dialog box.

As with editing the attributes ofany feature, editing eventattributes takes place within anedit session. You start an editsession by clicking StartEditing from the Editor menu onthe Editor toolbar. Once youbegin an edit session, you’llnotice the Sketch tool nextto the Options button on thetable window, indicating thetable can be edited. u

Tip

Dynamic segmentationWhen displayed as a feature layer,editing an event’s route locationfield will cause the event’s locationto be dynamically resegmented.

Editing event recordsusing the table window

1. Click the Editor menu andclick Start Editing if you havenot started an edit session.

2. Open the event table youwant to edit.

You can open either a stand-alone event table or one thathas been added to ArcMapas a feature layer. For moreinformation, see ‘Addingroute events’ in Chapter 5.

3. Click the cell containing theattribute value you want tochange.

4. Type the value and pressEnter.

The table is updated.Tip

Adding the Editor toolbarTo display the Editor toolbar, clickTools and click Editor Toolbar.

Tip

Saving your edits oftenClick the Editor menu and clickSave Edits.

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Adding new eventrecords using the tablewindow



3. Click the arrow on the right tomove to the end of the table.

4. Click a cell in the last recordand type in a new value.

NOTE: If your events tablehas been added to ArcMapas a feature layer, the newevent will appear on the maponce valid route locationvalues have been set. Formore information, see‘Adding route events’ inChapter 5.

Deleting event recordsusing the table window



3. Select the records you want todelete. Press and hold the Ctrlkey while clicking to selectmore than one record.

4. Press the Delete key on thekeyboard.

See Also

For more information on tableediting techniques, such as copyingand pasting records and makingsimple and advanced fieldcalculations, see Using ArcMap.

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In addition, those fields thatyou can edit will have a whitebackground color for the fieldheading.

You make attribute changes byclicking a cell and typing a newvalue. If you make a mistake,you can easily undo the edit byclicking Undo from the Editmenu.

Editing attributes through thetable window allows you toquickly make changes toseveral records at once. Whenyou’re editing the attributes ofa specific event, you may find itmore convenient to use theAttribute dialog box, which isaccessed from the Editortoolbar. To use the Attributesdialog box with events, youmust first add your events toArcMap as a feature layer. Formore information, see ‘Addingroute events’ in Chapter 5.

The Attributes dialog box hastwo sides. The left side lists thefeatures you have selected.Features are listed by theirprimary display field and aregrouped by layer name. u


Editing event recordsusing the Attributesdialog box


2. Click the Edit tool.

3. Select the events whoseattributes you want to edit.

4. Click the Attributes button.

5. Click the primary displayfield of the event feature forwhich you want to modify anattribute value.

6. Click the value you want tomodify.

7. Type a new value and pressEnter.

The attribute is modified forthe event feature.

Tip

Events as a feature layerFor events to be edited with theAttributes dialog box, they must bedisplayed in ArcMap as a featurelayer.

Tip

Noneditable tablesSome event tables cannot beedited—for example, delimited textfiles and tables accessed throughan OLE DB connection.

Tip

Noneditable fieldsIf you are editing your events afterthey have been added to the map asa feature layer, some fields will notbe editable. These are the fieldsthat are generated by the dynamicsegmentation process: Shape,Loc_Error, and Loc_Angle.

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The right side shows theattribute field names and theirvalues.

When you’ve completed youredits, you can save them andend the edit session.

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For more information on editingattributes with the Attributes dialogbox, see Editing in ArcMap.

Deleting event recordsusing the Attributesdialog box


2. Click the Edit tool.

3. Select the event you want todelete.

4. Click the Attributes button.

5. Right-click the primarydisplay field of the eventfeature you want to deleteand click Delete.

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12aliasAn alternative name specified for fields, tables, and feature classes that is more descriptive and

user-friendly than the actual name of these items. On computer networks, a single e-mail aliasmay refer to a group of e-mail addresses. In database management systems, aliases can containcharacters, such as spaces, that can’t be included in the actual names.

attribute1. Information about a geographic feature in a GIS, generally stored in a table and linked to the

feature by a unique identifier. For example, attributes of a river might include its name, length,and average depth.

2. In raster datasets, information associated with each unique value of raster cells.

3. Cartographic information that specifies how features are displayed and labeled on a map; thecartographic attributes of a river might include line thickness, line length, color, and font.

bookmarkSee spatial bookmark.

CADA computer-based system for the design, drafting, and display of graphical information. Alsoknown as computer-aided design, such systems are most commonly used to support engineeringplanning and illustrating activities.

calibrationComparing the accuracy of an instrument’s measurements to a known standard.

Catalog treeIn ArcCatalog, a hierarchical view of folder connections that provide access to GIS data stored onlocal disks or shared on a network, and allows users to manage connections to databases and GISservers.

computer-aided design (CAD)See CAD.

Glossary


concatenate eventsIn linear referencing, a command that combines event records intables containing events on the same route with the same valuefor specified fields. Only events in situations where the to-measure of one event matches the from-measure of the next eventare combined. The concatenate events command is available forline event tables only.

coordinate systemA fixed reference framework superimposed onto the surface of anarea to designate the position of a point within it; a referencesystem consisting of a set of points, lines and/or surfaces, and aset of rules used to define the positions of points in space ineither two or three dimensions. The Cartesian coordinate systemand the geographic coordinate system used on the earth’ssurface are common examples of coordinate systems.

coverageA data model for storing geographic features using ArcInfosoftware. A coverage stores a set of thematically associated dataconsidered to be a unit. It usually represents a single layer, suchas soils, streams, roads, or land use. In a coverage, features arestored as both primary features (points, arcs, polygons) andsecondary features (tics, links, annotation). Feature attributes aredescribed and stored independently in feature attribute tables.Coverages cannot be edited in ArcGIS.

database management system (DBMS)A set of computer programs that organizes the information in adatabase according to a conceptual schema and provides toolsfor data input, verification, storage, modification, and retrieval.

DBMSSee database management system (DBMS).

dissolve route eventsIn linear referencing, a procedure that combines event records intables where there are events on the same route that have thesame value for specified fields. The Dissolve Route Events toolcombines events when there is measure overlap and is availablefor both line and point event tables.

dynamic segmentationThe process of calculating the shapes of point and line routeevents at run time.

edit sessionIn ArcMap, the environment in which spatial and attribute editingtakes place. After starting an edit session, a user can modifyfeature locations, geometry, or attributes. Modifications are notsaved unless the user explicitly chooses to save them.

Editor toolbarIn ArcMap, a set of tools that allows the creation andmodification of features and their attributes.

end hatch definitionIn linear referencing, a special type of hatch definition that drawshatch marks only at the low and high measure of a linear feature.

environment settingsSettings that can apply to all tools within the application, all toolswithin a model or script, or a particular process within a model orscript. Environment settings include current workspace, outputspatial reference, output spatial grids, cell size, and tile size. Theyare generally set before running tools.

GLOSSARY 149

eventA geographic location stored in tabular rather than spatial form.Event types include address events; route events; x,y events;and temporal events. Address events are features that can belocated based on address matching with a street network or otheraddress identifier such as ZIP Codes or lot numbers. Routeevents are linear, continuous, or point features occurring along abase route system. X,y events are simple coordinate pairs thatdescribe the location of a feature, such as a set of latitude andlongitude degrees. Temporal events are used to describeobservations through time of particular objects or groups ofobjects.

event locationSee event.

event overlayIn linear referencing, an operation that produces a route eventtable that is the logical intersection or union of two input routeevent tables. Event overlay is one way to perform line-on-line,line-on-point, and event point-on-point overlays.

event tableA data source containing location information in tabular format(called events) that is used to create a spatial dataset.

event transformSee transform events.

extrapolationThe inference or calculation of unknown values from valueswhich are currently known; a method or technique of projectingor extending data or inferences beyond known values so as toarrive at conjectural knowledge of unknown data or inferences.

featuresA representation of a real-world object on a map. Features can berepresented in a GIS as vector data (points, lines, or polygons) oras cells in a raster data format. To be displayed in a GIS, featuresmust have geometry and locational information.

feature classA collection of geographic features with the same geometry type(such as point, line, or polygon), the same attributes, and thesame spatial reference. Feature classes can stand alone within ageodatabase or they can be contained within shapefiles,coverages, or other feature datasets. Feature classes allowhomogeneous features to be grouped into a single unit for datastorage purposes. For example, highways, primary roads, andsecondary roads can be grouped into a line feature class named“roads.” In a geodatabase, feature classes can also storeannotation and dimensions.

feature datasetA collection of feature classes stored together that share thesame spatial reference; that is, they have the same coordinatesystem, and their features fall within a common geographic area.Feature classes with different geometry types may be stored in afeature dataset.

fieldA column in a table that stores the values for a single attribute.

See also attribute.

GDBSee geodatabase.


geodatabaseAn object-oriented data model introduced by ESRI thatrepresents geographic features and attributes as objects and therelationships between objects, but is hosted inside a relationaldatabase management system. A geodatabase can store featureclasses, feature datasets, nonspatial tables, and relationshipclasses.

hatch classIn linear referencing, a group or category of hatch definitions.

hatch definitionIn linear referencing, a specification for where hatch marks aredrawn on a linear feature. Each hatch definition has its own set ofproperties that include the multiple of the hatch interval at whichthe hatches in the hatch definition will be placed, the line ormarker symbol of the hatches, and whether the hatches will belabeled. The use of multiple hatch definitions allows for thedesign of complex hatching schemes.

hatch styleIn linear referencing, an organized collection of symbols andsettings for the hatch definitions that make up a hatch class.Hatch styles are stored in a style file (.style) and created by theuser to maintain standards for displaying hatches on multiplemaps with multiple data sources.

hatchesIn linear referencing, a series of vertical line or marker symbolsdisplayed on top of features at an interval specified in routemeasure units.

hatchingIn linear referencing, a type of labeling that is designed to postand label hatch marks or symbols at a regular interval alongmeasured linear features.

identityA topological overlay that computes the geometric intersection oftwo coverages. The output coverage preserves all the features ofthe first coverage plus those portions of the second (polygon)coverage that overlap the first. For example, a road passingthrough two counties would be split into two arc features, eachwith the attributes of the road and the county it passes through.

See also intersect, union.

indexA data structure used to speed the search for records in adatabase or for spatial features in geographic datasets. In general,unique identifiers stored in a key field point to records or filesholding more detailed information.

interpolationIn the context of linear referencing, the calculation of measurevalues for a route between two known measure values.

intersectA geometric integration of spatial datasets that preserves featuresor portions of features that fall within areas common to the inputdatasets.

See also identity, union.

itemSee field.

GLOSSARY 151

join1. Appending the fields of one table to those of another through

an attribute or item common to both tables. A join is usuallyused to attach more attributes to the attribute table of ageographic layer.

2. The process of connecting two or more separate spatialentities. If two line segments are joined, they become onespatial object for further processing.

layerA set of references to data sources, such as a coverage,geodatabase feature class, raster, and so on, that defines how thedata should be displayed on a map. Layers can also defineadditional properties, such as which features from the data sourceare included. Layers can also be used as inputs to geoprocessingtools. Layers can be stored in map documents (.mxd) or savedindividually as layer files (.lyr).

lineA shape having length and direction but no area, connecting atleast two x,y coordinates. Lines represent geographic features toonarrow to be displayed as an area at a given scale, such ascontours, street centerlines, or streams, or features with no areathat form the boundaries of polygons, such as state and countyboundary lines.

line eventIn linear referencing, a feature that describes a portion of a routeusing a from- and to-measure value. Examples include pavementquality, salmon spawning grounds, bus fares, pipe widths, andtraffic volumes.

linear featureSee line.

linear referencingA method for storing geographic data by using a relative positionalong an already existing linear feature; the ability to uniquelyidentify positions along lines without explicit x,y coordinates.Location is given in terms of a known linear feature and aposition, or measure, along it. Linear referencing is an intuitiveway to associate multiple sets of attributes to portions of linearfeatures.

See also dynamic segmentation.

line-on-line overlayIn linear referencing, the overlay of two line event tables toproduce a single line event table. The new event table can be thelogical intersection or union of the input tables.

line-on-point overlayIn linear referencing, the overlay of a line event table and a pointevent table to produce a single point event table. The new eventtable can be the logical intersection or union of the input tables.

map1. A graphic depiction on a flat surface of the physical features of

the whole or a part of the earth or other body, or of theheavens, using shapes to represent objects and symbols todescribe their nature; at a scale whose representative fractionis less than 1:1. Maps generally use a specified projection andindicate the direction of orientation.

2. The document used in ArcMap to display and work withgeographic data. In ArcMap, a map contains one or morelayers of geographic data, contained in data frames, andvarious supporting map elements, such as a scale bar.

map featureSee feature.


map projectionSee projection.

map scaleSee scale.

MapTipIn ArcGIS, a user-assistance component that displays anonscreen description of a map feature when the mouse is pausedover that feature.

measureSee route measure.

measure location fieldsIn linear referencing, either one or two fields in a table thatdescribe the position of an event along a route.

measure valueSee m-value.

m-valueMeasure value or vertex attributes. M-values may be added tolinear features to perform dynamic segmentation.

NaNNot a number.

OLE DB providerObject Linking and Embedding database provider. A toolconforming to the OLE standard for sharing data betweenapplications. Each OLE DB provider communicates with andretrieves data from a different database, but a user can work withthe data retrieved by any OLE DB provider in a similar way.

overlay eventsSee event overlay.

point eventIn linear referencing, a feature that occurs at a precise pointlocation along a route; it uses a single measure value. Examplesinclude accident locations along highways, signals along raillines, bus stops along bus routes, and pumping stations alongpipelines.

point-on-line overlaySee line-on-point overlay.

polylineA two-dimensional feature representing a line containing one ormore line segments—that is, any line defined by two or morepoints. Line features such as boundaries, roads, streams, andstreets are usually polylines.

projectionA method by which the curved surface of the earth is portrayedon a flat surface. This generally requires a systematicmathematical transformation of the earth’s graticule of lines oflongitude and latitude onto a plane. It can be visualized as atransparent globe with a light bulb at its center casting lines oflatitude and longitude onto a sheet of paper. Generally, the paperis either flat and placed tangent to the globe (a planar or azimuthalprojection), or formed into a cone or cylinder and placed over theglobe (cylindrical and conical projections). Every map projectiondistorts distance, area, shape, direction, or some combinationthereof.

GLOSSARY 153

rasterA spatial data model that defines space as an array of equallysized cells arranged in rows and columns. Each cell contains anattribute value and location coordinates. Unlike a vectorstructure, which stores coordinates explicitly, raster coordinatesare contained in the ordering of the matrix. Groups of cells thatshare the same value represent geographic features.

See also vector.

river addressingIn hydrology applications, another name for linear referencing.River addressing allows objects, such as field monitoringstations, which collect information about water quality analysis,toxic release inventories, drinking water supplies, flow, and so on,to be located along a river or stream system.

routeAny linear feature, such as a city, street, highway, river, or pipe,that has a unique identifier and a measurement system storedwith the geometry.

Route Editing toolbarA set of tools that allows you to create and modify routes inArcMap.

route eventSee event.

route event sourceIn linear referencing, the result of the dynamic segmentationprocess. A route event source serves an event table as a dynamicfeature class. Every row in the table is served as a feature whoseshape is calculated when needed. For example, a route eventsource can act as the basis of a feature layer in ArcMap.

route event tableIn linear referencing, a table that stores route locations and theirattributes. A route event table, at a minimum, consists of a routeidentifier field and a measure location field (point events) or fields(line events).

route feature classSee route reference.

route identifierIn linear referencing, a numeric or character value used to identifya route.

route locationIn linear referencing, a discrete location along a route (point) or aportion of a route (line). A point route location uses only a singlemeasure value to describe a discrete location along a route. A lineroute location uses both a from- and to-measure value to describea portion of a route.

route measureIn linear referencing, a value stored along a linear feature thatrepresents a location relative to the beginning of the feature, orsome point along it, rather than as an x,y coordinate. Measuresare used to map events such as distance, time, or addresses alonglinear features.

See also route, dynamic segmentation.

route measure anomaliesIn linear referencing, route measure values that do not adhere tothe expected behavior. They can often be fixed with ArcMaproute editing tools.


route referenceIn linear referencing, a collection of routes with a common systemof measurement stored in a single feature class (for example, a setof all highways in a county).

scaleThe ratio or relationship between a distance or area on a map andon the corresponding distance or area on the ground, commonlyexpressed as a fraction or ratio. A map scale of 1/100,000 or1:100,000 means that one unit of measure on the map equals100,000 of the same unit on the earth.

selected setA subset of features in a layer or records in a table that is chosenby the user.

shapefileA vector data storage format for storing the location, shape, andattributes of geographic features. A shapefile is stored in a set ofrelated files and contains one feature class.

sketchIn ArcMap, a shape that represents a feature’s geometry. Everyexisting feature on a map has this alternate form, a sketch, thatallows visualization of that feature’s composition, with all verticesand segments of the feature visible. When features are edited inArcMap, the sketch is modified, not the original features. Asketch must be created in order to create a feature. Only line andpolygon sketches can be created, since points have neithervertices nor segments.

snapping environmentSettings in the ArcMap Snapping Environment window andEditing Options dialog box that define the conditions in whichsnapping will occur. These settings include snapping tolerance,snapping properties, and snapping priority.

spatial bookmarkIn ArcMap, a shortcut created by the user that identifies aparticular geographic location to be saved for later reference.

spatial domainFor a spatial dataset, the defined precision and allowable rangefor x and y coordinates and for m- and z-values, if present. Thespatial domain must be specified by the user when creating ageodatabase feature dataset or standalone feature class.

spatial referenceThe coordinate system used to store a spatial dataset. For featureclasses and feature datasets within a geodatabase, the spatialreference also includes the spatial domain.

SQLSee Structured Query Language (SQL).

stationingIn the pipeline industry, another name for linear referencing.Stationing allows any point along a pipeline to be uniquelyidentified.

Structured Query Language (SQL)A syntax for defining and manipulating data from a relationaldatabase. Developed by IBM in the 1970s, SQL has become anindustry standard for query languages in most relational databasemanagement systems.

symbolA graphic representation of a geographic feature or feature classon a map. For example, line symbols represent arc features; markersymbols, points; shade symbols, polygons; and text symbols,annotation. Many characteristics define symbols including color,size, angle, and pattern.

GLOSSARY 155

tableA set of data elements arranged in rows and columns. Each rowrepresents an individual entity, record, or feature, and eachcolumn represents a single field or attribute value. A table has aspecified number of columns but can have any number of rows.

topologyThe geometric relationships, determined mathematically, betweenconnecting or adjacent features in a geographic dataset.Topology may include information about connectivity, direction,length, adjacency, and polygon definition. Topology makes mosttypes of geographic analysis possible because it allows analysisof spatial relationships between features.

transform eventsIn linear referencing, an operation that produces a new table bycopying and transforming events from one route reference toanother. This allows the events to be used with a route referencehaving different route identifiers and/or measures.

unionA topological overlay of two polygonal spatial datasets thatpreserve features that fall within the spatial extent of either inputdataset; that is, all features from both coverages are retained.

See also intersect and identity.

Universal Transverse MercatorSee UTM.

UTMUniversal Transverse Mercator. A projected coordinate systemthat divides the world into 60 north and south zones, six degreeswide.

variableA symbol or quantity that can represent any value or set ofvalues, such as a text string or number. Variables may changedepending on how they are used and applied. They are usedfrequently in mathematics and computing.

vectorA coordinate-based data model that represents geographicfeatures as points, lines, and polygons. Each point feature isrepresented as a single coordinate pair, while line and polygonfeatures are represented as ordered lists of vertices. Attributes areassociated with each feature, as opposed to a raster data model,which associates attributes with grid cells.

See also raster.

vector data modelAn abstraction of the real world in which spatial elements arerepresented in the form of points, lines, and polygons. These aregeographically referenced to a coordinate system.

vector modelSee vector data model.

vertexOne of a set of ordered x,y coordinate pairs that define a line orpolygon feature.

wizardAn interactive user interface that helps a user complete a task onestep at a time. It is often implemented as a sequence of dialogboxes that the user can move through, filling in required details. Awizard is usually used for long, difficult, or complex tasks.


workspaceA container for geographic data. A workspace can be a folder thatcontains shapefiles, an ArcInfo workspace that containscoverages, a geodatabase, or a feature dataset.

zero length line eventIn linear referencing, a line event whose from-measure is equal toits to-measure. This can happen, for example, when locatingpolygons along routes, and a polygon touches a route but doesnot overlap it.

157

12Index A

Accidentslocating 43

Addingroute events 101, 133

Advanceddynamic segmentation 99

Aggregatingroute events 135

Algorithmhatching 79

Aliasdefined 147

Altering route measuresupdating 125

Angleof event 100

ArcCatalog 49ArcInfo Workstation 50ArcSDE

storing routes 50ArcToolbox 49, 50Attributes 5, 95

defined 147for linear referencing 42linearly referenced 44storing multiple sets 44

Automatingevent table creation 122

B

Bookmark. See also Spatial bookmarkdefined 147using 22

Breaking upevent tables 124, 135

C

CAD (Computer-aided design) 64defined 147input feature class 14

Calculating route measures with points. SeeCalibrating routes

Calibrate Routes tool 16Calibrating routes 114

described 52, 66, 113digitizing points

order of 114undoing 113

disjointed routes 53, 114using measure distance 53, 66using shortest path distance 52, 66with points 113

Calibrationdefined 147points 114ratio 114

Catalog treedefined 147

Character field 72Combining

event data 125event records 124event tables 122overlapping measures 135

Complexhatching 85routes 107, 111

creating 109Computer-aided design 147. See also CADConcatenating events

defined 148described 124

Constraintson route measures 98


Convertingfeet to miles 109hatches to graphics 87, 92

add command 90route data

coverage to geodatabase 69–70Coordinate priority 50, 108Coordinate system

defined 148described 45

Coordinates or measures out of bounds 110Copying

data 10hatch definition 89

Coveragedefined 148

Coverage datasetsmigrating route datasets

to a geodatabase 69–70Coverage route data 50Coverage route system

migrating to a geodatabase 69–70Create Routes tool 14Creating

complex route 109event data 122geodatabase event table 128INFO event table 131layer 12route event tables 128–129route features 105routes 107simple route 107workspace 131

D

Datacopying 10organizing

in ArcCatalog 10segmented 43storing

as a multipoint feature 42as a point feature 42as a polygon feature 42as a polyline feature 42

Data storagevector model 43

Database management systemdefined 148

dBASEcreating event tables 130OID field 130

DBMS. See Database management systemDecimal number

displayed 119Delimited text file 99Discrete locations 45Disjointed routes 114Display symbol

changing 19Displaying

hatches 85Dissolve events

described 124Dissolve operation

defined 148Dissolve Route Events tool 135Dissolving

route events 135Dynamic

feature class 99feature layer 99

Dynamic (continued)segmentation 102. See also Route events

advanced options 102defined 148described 42, 99–100using attribute indexes 101

DynSeg. See Dynamic segmentation

E

Edit sessiondefined 148

Edit Sketch Properties 117Edit tool 107Editing

event data 127event tables 127linear features 105route features 105routes 105

Editor toolbar 107adding 106, 142defined 148

Editssaving 40, 142

End hatch 79, 82tolerance 77, 82

End hatch definitiondefined 148described 77view 82

End hatch tolerance 79Endpoint 108Environment settings

defined 148esri_measure 93

INDEX 159

Event. See also Route eventsdata 71defined 149errors 100overlaying 122rows of a table 44tables 44, 122

Event angle 100Event data

aggregating 124concatenating 124creating 122dissolving 124editing 127storing

in dBASE tables 122in geodatabases 122in INFO tables 122in text files 122

Event layersintersecting 29saving 102

Event location. See EventEvent measures

transforming 125, 137–138with the field calculator 137

updating 125Event overlay

defined 149Event records

addingusing the table window 143

deletingusing the table window 143with the Attributes dialog box 145

editingusing the Attributes dialog box 144using the table window 142

Event table. See also Route event tablecombine 122defined 149

field names 129removing redundant information 124requirements 128

Event transform. See also Route eventsdefined 149

Events 45. See also Route eventsExisting routes

editing 115Extrapolation

defined 149

F

Feature classdefined 149described 45using as a template 58

Feature class to geodatabase script 69–70Feature datasets

defined 149described 45with multiple route feature classes 45

Featuresdefined 149described 1linear

described 41locating along routes 140–141merging 43modifying 117multipoint 99splitting 43storing as relative locations 43

Fielddefined 149OBJECTID 129OID in dBASE 130

Field namesfor event tables 129

Fieldscalculating 137for route locations 128noneditable 144route identifier 72

Folder connectioncreating 10making a new 11

From/To measuressetting 118

G

Geodatabasedefined 150event tables

creating 128–129OBJECTID field 129

Geographic data modeling 42Geometric length 109Graphics

saving 92Grid size 55

H

Hatchangle 79class 81, 85–87

offset 78scale range 86

definition 77, 81, 83, 85–87labeling 93offset 78

interval 79, 83, 87offset 83orientation 81placement options 80, 81style 80tab 80using a SQL query 80


Hatch classassociating a SQL query 86defined 150described 77removing 89saving as a hatch style 96viewing 80

Hatch definitioncopying 89defined 150viewing 81

Hatch Orientation dialog box 84Hatch Placement Options dialog box 83Hatch style

applying to a hatch class 97creating in the Style Manager 95defined 150described 95saving 96

Hatch Style dialog boxaccessing 96

Hatch tolerancemeasure units 79

Hatches 85–87converting to graphics 87, 90, 92

adding the command 90creating and managing 79defined 150described 85–87displaying 85generating text with a script 93importing 88intervals of 78manipulating text 93nonappearing 87overlapping with labels 87scaling with the map 88stopping the drawing process 87turning on 86

Hatchingalgorithm 79defined 150described 77distance-based measures 77nondistance-based measures 77options 78

I

ID fielddeleting 63

Identifierof a route 44

Identify Route Locations tooladding 21, 73not enabled 74

Identitydefined 150

In-memoryfile 12layer 103

Indexdefined 150

INFO event tablescreating 128–129

Input widthdescribed 130

Interpolationdefined 150

Intersectdefined 150

Intersecting 115events 29. See also Overlay eventsroute events 122, 132routes and features 127routes and lines 127routes and points 126routes and polygons 127

Item. See Field; Field: defined

J

Joindefined 151

L

Label Settings dialog box 84Labeling 77

hatches 93Layer dropdown list

using 74Layer properties

of route data 72Layers

creating 12defined 151described 71in-memory 103

Linedefined 151

Line event 102defined 151described 46displaying on a map 27. See also Dynamic

segmentationLine features

locating along routes 127Line-on-line

overlay 132. See also Overlay eventsdefined 151

overlay events 122Line-on-point

overlay 132. See also Overlay eventsdefined 151

overlay events 123Linear feature 107

defined 151described 41edit 105

INDEX 161

Linear referencing 47defined 151described 41highways and streets 2method

described 47oil and gas exploration 5pipelines 6railways 4transit 3water resources 7

Locate Features Along Routes tool 140–141Locating

accidents 43event errors 100line features 127point features 126polygon features 127

Low measure 79

M

M domainchoosing 54

Make Layer tool 12Make Route command

described 35, 108Make route event layer 31Make Route Event Layer tool 103, 133Map

defined 151Map document

existingopening 18

Map feature. See Feature: definedMap projection. See Projection: definedMap scale. See Scale: definedMapTip

defined 152remeasuring portion of a line 119

Marker routes 45

Marker symbol 85Measure

symbols 77value 44, 45

units 45Measure distance. See Calibrating routesMeasure field 109Measure location fields

defined 152Measure locations 102Measure value 43, 105, 109, 115. See also

M-valuedefined 152updating 125

Measurement system 45Measures 45. See also Route measures

defined 152described 42, 45out of bounds 110setting as distance 117unknown (NaN) 45

Merging 115features 43

Milepost 42, 45Modeling

geographic data 42Multiple route references 125Multipoint features 99M-value

defined 152

N

NaNcalculating 116defined 152described 45

Networks 41New workspace 131Numeric field 72

O

OBJECTID field 129, 133OID field 130OLE DB provider

defined 152Overlapping segments

preserving 112Overlay events 122. See also Route events

defined 152intersecting 132line-on-line 122line-on-point 123unioning 132

Overlay Route Events tool 30

P

Point events 99defined 152described 46displaying on a map 26. See also Dynamic

segmentationPoint feature 99

locating along routes 126Point-on-line overlay

defined 152Point-on-point

overlaying 132Points

for calibration 114to calibrate routes 113

Polygon featureslocating along routes 127

Polylinedefined 152described 45storing a measurement system 45with multiple, connected paths 45with multiple, disjointed paths 45with one path 45


Precision 59Projection

defined 152Properties

of hatches 85

Q

Queryingroute data 71, 73

R

Rasters 42defined 153

Ratiofor calibration 114

Realigningupdating measures 125

Recalibratingupdating measures 125

Reference scalesetting 88

Referencinglinear

described 41Relative location

storing data as 43Remeasure routes 117Removing

redundant info from table 135River addressing

defined 153Road network 43Rotating labels 100Route

complex 107, 111data 71

layer properties 72identifier 44

Route (continued)locations

finding 73identifying 73

simple 107, 111Route data

adding to a map 19, 33calibrating 16converting

coverage to geodatabase 69–70creating 14

measure values are known 51measure values are not known 50

migratingto a geodatabase 69–70

querying 73Route editing 34Route Editing toolbar

addingusing the Customize dialog box 106using the Editor menu 106

defined 153Route event source 99

defined 153Route event table 102

automated techniques 122concatenating 124creating 122

in a geodatabase 128–129in ArcCatalog 128–129in dBASE 130in INFO 131

defined 153described 46, 121dissolving 124editing in ArcMap 142–143intersecting 123measure location 102route identifier 102

Route events 45, 99adding to a map 101. See also Dynamic

segmentationaggregating 135defined 153described 46, 101displaying 101dissolving 135–136editing 142intersecting 122overlaying 132, 132–133querying 28tables 44unioning 122

Route Events Geoprocessing Wizardaggregating events. See Dissolve eventslocating points along routes. See Point

featurelocating polygons along routes. See Polygon

featuresoverlaying events. See

Intersecting; Unioningtransforming events. See Transform eventsusing 134, 135, 139

Route feature classcreating

in a geodatabase 57in an existing feature dataset 60

defined 153Route features

creating 105editing 105

Route identifier 102creating an index 60, 62defined 153described 72saving 72setting 20, 37, 72, 76values 74

INDEX 163

Route locationdefined 153described 46, 101fields 128finding 23, 76identifying 22, 74labeling 75

Route measure anomaliesdefined 153described 24, 98displaying 24, 98

using a scale range 98using a SQL query 98

Route measures. See also Measuresanomalies 98calculating using points 52. See also

Calibrating routesconstraints 98converting units 38defined 153editing

with an edit sketch 117labeling 93setting 115

using Apply Factor 116using Calculate NaN 116using Drop Measures 116using Offset 116using Set As Distance 115using Set Direction As M 116using Set From/To 116

updating 126Route reference. See also Linear referencing

methoddefined 154multiple 125

Route structure 138

Routescalibrating with points 66creating 107

by merging linear features 50from existing lines 64–65

defined 153described 45, 50editing 33in coverages 50locating features along 140making from selected features 35, 107realigning 118recalibrating 39remeasuring 117, 119storing 50

S

Scaledefined 154

Scale suppression 22Script

feature class to geodatabase 69–70Segmentation 43

dynamic 42Segmented data 43Selected set

defined 154Shapefile

creating to store routes 61defined 154

Shortest path distance 66. See also Calibratingroutes

Shotpointdescribed 5

Simple route 111creating 107

Sketchdefined 154tool 113

Snapping environmentdefined 154

Spatialbookmark

defined 154domain

defined 154gap 114reference

defined 154Splitting features 43SQL. See Structured Query LanguageStandalone feature class

creating to store routes 57–60Start measure 110Start point 108Starting priority. See Coordinate priorityStationing

defined 154Storing

attributes 43features

as relative locations 43routes 50

Structured Query Languagedefined 154

Stylefile 95Manager 95

Symboldefined 154selector 20

Symbolizationhatching 81

Symbology selection 20System of measurement 43


T

Tablesdefined 155noneditable 144route events 44

Target annotationnonappearing 92

Target feature class 110–111setting 34

Texton hatches 93

TIN 42Tolerances

choosing 138of end hatch 77

ToolCalibrate Routes 66–68Create Routes 64Dissolve Route Events 135Edit 107Locate Features Along Routes 140–141Make Route Event Layer 103, 133Overlay Route Events 132–133Transform Route Events 125, 138

Toolbaradding 34route editing 106

Topologydefined 155described 47with multiple linear referencing methods 47

Transform events. See also Route eventsdefined 155

Transform Route Events tool 138Transforming

event measures 137using field calculator 137using tool 138

route events 125

U

Uniondefined 155

Unioning 115events. See Overlay eventsroute events 122, 132

Universal Transverse Mercator (UTM)defined 155

Updatingevent measures 125measure values 125

UTM (Universal Transverse Mercator)defined 155described 45

V

Valuesof measure 44, 45

Variabledefined 155

Vector 42defined 155

Vector data modeldefined 155

Vector formatdescribed 42

Vector model. See also Vector data modeldefined 155described 43

Vertexdefined 155

W

Wizarddefined 155Route Events Geoprocessing 134, 135, 139

Workspacecreating 131defined 156

Z

Zero length line eventdefined 156described 141

Linear Referencing in ArcGIS - MAGTUG · 2 LINEAR REFERENCING IN ARCGIS Most applications that use...

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