WLIA Feb 23, 2005

Moving to a Shared Parcel Data Model

Eric Damkot - Washington County GIS Manager

Mat Dvorachek - City of West Bend GIS Analyst

WLIA Feb 23, 2005

Presentation Outline

• Background

• Developing the model

• Migrating data

• Integrating with external non-spatial data

• Roll-out

• What’s next?

• Summary

• Questions

WLIA Feb 23, 2005

Washington County

• 432 Square Miles• Population 120,000• 13 Townships, 5

Villages and 2 Cities (Plus

1 City of Milwaukee Parcel)

• Maintains Parcel Data for all municipalities except City of West Bend.

44,000 Parcels

WLIA Feb 23, 2005

City of West Bend

• Largest Municipality in Washington County

14.3 Square Miles• Population 29,000• Maintains parcel data

for the City 10,500 Parcels

WLIA Feb 23, 2005

Previous Mapping Environment

• Washington County– Intergraph MGE/Bentley Microstation– Design file format (.dgn)

• City of West Bend– ESRI ArcInfo 7– Coverage format

Data were shared by exchanging shape files. Although the data were compatible, nomenclature and formatting varied. A countywide analysis involving parcels typically required the analysis to be run independently for each data set and the results merged.

WLIA Feb 23, 2005

Independently...

Washington County decides to change GIS software vendors and implement ArcGIS and ArcSDE

City of West Bend decides to upgrade to ArcGIS and migrate parcel data to a personal GeoDatabase

Instead of working on parallel projects independently, technical staff from the City and County agreed to work together and attempt to design a single parcel data model.

WLIA Feb 23, 2005

Goals for the Data Model

• Maintain all existing functionality

• Add desired functionality that was missing from existing systems

• Streamline data maintenance procedures

• Simplify data exchange

• Simplify data analysis

• Eliminate the need to map overlapping areas

WLIA Feb 23, 2005

Procedure at a glance

Inventory all existing data.

Inventory all existing data.

Identify otherneeds

Identify otherneeds

Identify areas in common and areas

of difference

Determine the scope

of cooperation

Load Dataand Test

Load Dataand Test

ReviseData Model

RE

PE

AT

County StepCity StepJoint Step

Create DraftData Model

WLIA Feb 23, 2005

Areas where we could cooperate...

PLSS MonumentsPLSS TownshipsPLSS Township AnnotationPLSS SectionsPLSS Section AnnotationPLSS Quarter SectionsPLSS Quarter Section AnnotationPLSS Government LotsPLSS Government Lot AnnotationPLSS LinesMunicipalityMunicipality AnnotationPlatted Land

Platted Land AnnotationSubdivision BlocksSubdivision Block AnnotationSubdivision/CSM LotsSubdivision/CSM Lot AnnotationParcelsParcel Tax Key AnnotationParcel Acreage AnnotationParcel Dimension AnnotationRight of WayRight of Way Name AnnotationRight of Way Dimension AnnotationConstruction Lines

Features

Topology Rules

Naming Conventions

Division of Mapping Responsibility

Most Attributes

Domains

WLIA Feb 23, 2005

Areas where we couldn’t

• Annotation sizes, fonts, placement, etc…

• Features needed for hard copy map production (I.e. leader lines, curve tangent markers etc…)

• Unique attribute requirements (Some attributes are used by only the City OR the County)

• Some legacy digitizing rules (I.e. Extend parcels into the right of way or not)

WLIA Feb 23, 2005

Where to Start...

You don’t need to start from scratch– http://support.esri.com/index.cfm?fa=downloads.dataModels.gateway

• Visio diagrams, repositories, sample pGDB, White papers, posters, user forums, case studies, etc…

– Peers– Consultants

It was a lot easier for us to start with something others had already developed then it would have been if we started with a blank page!

WLIA Feb 23, 2005

On the other hand

Everyone has unique requirements when it comesto parcel mapping. Recognize those differencesand design your data model to best address yourneeds.

Don’t be afraid to make changes to whatevermodel you decide to use as a starting point.

WLIA Feb 23, 2005

Decision Points

• What area features do you also need to maintain as lines?

• What needs to be it’s own feature class and what should be a subtype?

• What annotation should be feature linked?

• How will you model Condominiums?

• How are your features related? What topology rules, relationship classes, etc… will you need to enforce these relationships?

WLIA Feb 23, 2005

Creating Topologies

All features that participate in a topology must be in the same feature dataset. This limitation may dictate how data are organized in the GeoDatabase.

Topology - Rules and properties of the spatial relationships between features. Provides an environment for editing coincident geometry with editing tools.

Based on the defined cluster tolerance, validating topology will add, delete, and move the vertices of participating features.

Use this to your advantage

But don’t hurt yourself!

WLIA Feb 23, 2005

Goals for the Data Model

• Maintain all existing functionality

• Add desired functionality that was missing from existing systems

• Streamline data maintenance procedures

• Simplify data exchange

• Simplify data analysis

• Eliminate the need to map overlapping areas

WE DID IT!

WLIA Feb 23, 2005

New Mapping Environment

• A common data model to house cadastral related data– City of West Bend uses a personal Geodatabase and

maintains data within the Cities’ corporate limit

– Washington County maps the remainder of the County in ArcSDE/MS SQL 2000

– Small portions of the model are only used by one mapping agency

• Data are shared and appended in personal Geodatabases with plans to automate the process using model builder.

WLIA Feb 23, 2005

Importing Data (County)

Washington County imported data from a CAD based environment into the new data model

Process• Recreate county-wide PLSS dataset.

• Edge match, clean and reformat data in native environment

• Import polygon features into appropriate feature classes (MGE/Microstation - GeoMedia - ArcGIS)

• Import line and annotation features into appropriate feature classes (MGE/Microstation - ArcGIS)

• Calculated subtypes based on imported CAD attributes

• Validate topology and fix errors

Rule of Thumb - Complete as much data reformatting and cleaning as possible before importing into the GDB. Use ArcGIS and topology to perform fine tuning and final data validation.

WLIA Feb 23, 2005

Importing Data (City)

City imported data from a coverage-based environment into new data model.

Process• Replace City’s PLSS dataset with county-wide dataset.• Pre-process coverage datasets to facilitate subsequent import.

– calculate Domain and Subtype codes– remedy field definition issues

• Imported existing vector data into the appropriate feature classes.• Create Block and Lot features in pilot area (City hadn’t modeled these.)• Copied existing GDB annotation feature classes into the model.• Validated topology and corrected errors.

WLIA Feb 23, 2005

Data Maintenance

• Workflow remained essentially the same.• Update Procedures

1. Receive Plat, CSM, etc.2. Enter exterior boundary into Construction_Line layer as

Two-Point Line Features using the Traverse tool.3. Adjust Traverse4. Reconcile with surrounding features5. Proportion Lines6. Add interior lot lines7. Use Construct Features tool to create Parcels, Lots,

Blocks, Plat, ROW, etc. from Construction_Line features.8. Attribute Data

WLIA Feb 23, 2005

Data Maintenance Cont.

• Relationship Classes– Organization of Data– Integrity of Data– Maintenance of Data

• Subtypes

• Annotation

WLIA Feb 23, 2005

The Good and the Bad

• Bad– Topology is sometimes difficult to work with.– Polygons don’t always behave themselves.– Other quirks

• Good– Maintenance is quicker– Data Integrity– Display in ArcMap provides versatility

WLIA Feb 23, 2005

Useful Add-ins

• GeoDatabase Diagrammer (Requires Visio)– http://arcscripts.esri.com/details.asp?dbid=13616– ArcCatalog command that will create a Visio

diagram of your geodatabase. The diagram will replicate the look and feel of the standard ESRI data model posters

– You will have to move things around and add descriptive text.

– We found it very helpful to visually see the model to better understand and model data relationships.

WLIA Feb 23, 2005

Useful Add-ins

• Parcel Extension– http://arcscripts.esri.com/details.asp?dbid=13589– ArcMap command that includes an additional

toolset specific to parcel mapping.– We’ve found the annotation placement tools to be

the most useful. Specially, the tool provides an enhanced method to create cartographic annotation in one feature from the COGO attributes of our construction line features.

WLIA Feb 23, 2005

Integrating with External Tax Data

Tax roll data is stored in an AS400/DB2 database. Using the data natively in the GIS is difficult because:

– Very flat– Cryptic naming conventions– Some attributes not even used– Not all portions of the table are updated at the same

time of the year– Unique tax key stored as two attributes (municipal

code and PID)– Access speed

WLIA Feb 23, 2005

Integrating with External Tax Data

• In Microsoft SQL Server Create Data Transformation Service (DTS) Package– Import Data from AS400– Create a new attribute with a concatenated version of municipal code

and Parcel Identification Number– Reformat various other attributes for more convenient use in the GIS– Parcel out the data from the Tax Master table into newly created,

logically organized user tables.

• These DTS packages are scheduled to run during non-peak hours

The resulting system provides data from the tax database that is available in the GIS near real-time and is more convenient to use.

WLIA Feb 23, 2005

Getting Buy-In From The Users

Remember - changing mapping environments may create a larger task for the people using the data then for the people actually doing the migration and parcel mapping. These users could have hundreds of maps pointing to the old data and may not be the most technical staff in your organization.

Be patient!

WLIA Feb 23, 2005

How to Ease the Transition

• Give many warnings well in advance of the cut-over

• Explain that you are not making the change because you enjoy seeing them suffer

• Provide specific examples to help them migrate maps and work flows.

• Continue to provide access to the old data for an extended period of time, but make sure they understand it is no longer being updated.

WLIA Feb 23, 2005

Where Do We Go From Here?

• MAN - Washington County will soon be connected to the City of West Bend’s Municipal Area Network.– The City should be able to view County ArcSDE data live!

– It would be technically possible for the City to store and edit their parcel data in the County’s ArcSDE database, but the politics of this arrangement maybe a challenge.

– County will gain better access to City data

• Work cooperatively to create models for other commonly maintained data. Road centerlines is the next likely target.

WLIA Feb 23, 2005

Summary

• Coordination between organizations is sometimes easiest if left to technical staff.

• Creating a new parcel data model and migrating data and work flows can seem like a daunting task. There are, however, many available resources and it can be done.

• The migration should be designed to improve efficiency and address inadequacies in existing systems.

• Don’t underestimate the impact the change will have on your organization. Prepare for it.

WLIA Feb 23, 2005

Questions