Gis Lab Manual 2

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Exercise 1:Digitizing Your Map with ArcView Aim: Digitization of toposheet Start ArcView and open a new view. Do not add any themes too your view at this point. Go too the View menu on the top and choose properties.In the View Properties Box you now see you can rename View1 to something else if you prefer.Under the creator box you may also fill in your own name. Under the Distance Units select units of distance that you like (i.e. miles, kilometers, inches, whatever) and then click ok again to exit the View Properties Box. If you are using the aerial photograph as your base map you should now load the air photo tiff file that is on the computer. If you used the topographic map as your base map you should load that instead. If the toposheet is already registered, start digitization otherwise register the toposheet and then start digitization. Digitizing your stuff: Go to the View menu and choose New Theme. For the feature choose a polygon and name it outline or something else if you prefer. Choose draw polygon tool and start digitization, to append the digitization to a polygon choose append line to polygon tool. Save editing using theme -> save edits. After the completion of the digitization stop editing and save edits. Similarly points and lines can be digitized in new separate themes.

Transcript of Gis Lab Manual 2

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Exercise 1:Digitizing Your Map with ArcView

Aim: Digitization of toposheet

Start ArcView and open a new view. Do not add any themes too your view at this point. Go too the View menu on the top and choose properties.In the View Properties Box you now see you can rename View1 to something else if you prefer.Under the creator box you may also fill in your own name. Under the Distance Units select units of distance that you like (i.e. miles, kilometers, inches, whatever) and then click ok again to exit the View Properties Box.

If you are using the aerial photograph as your base map you should now load the air photo tiff file that is on the computer. If you used the topographic map as your base map you should load that instead.

If the toposheet is already registered, start digitization otherwise register the toposheet and then start digitization.

Digitizing your stuff:

Go to the View menu and choose New Theme. For the feature choose a polygon and name it outline or something else if you prefer. Choose draw polygon tool and start digitization, to append the digitization to a polygon choose append line to polygon tool. Save editing using theme -> save edits. After the completion of the digitization stop editing and save edits. Similarly points and lines can be digitized in new separate themes.

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Exercise: 2 Thematic Mapping-1

Aim: Getting a Data into ArcView

What is a project?

A project is the file in which work you do in ArcView is stored. A project

typically contains all the view, tables, charts, layouts and scripts that

you use for a particular ArcView application. These are the components

of a project. For example, if you are using ArcView to find suitable

locations for a new office buildings, you would keep all the views,

tables, charts, layouts and scripts that you use in this application in

one project. In this way, your work is stored in one convenient place.

The next time you want to work on this application you simply open

this project file in ArcView and all the components you need are

available for you to use. Project files have an .apr extension.

Does a project contain my data?

A project file doesn't contain the actual data that you use in ArcView,

such as spatial data like shapefiles and ARC/INFO coverages, and

tabular data like dBASE files. Instead, a project stores references to the

location of these data sources on disk. In this way, the same data can

be used in any number of projects without duplication.

What's the Project window for?

When you open a project, all the components in the project are listed

in the Project window. From the Project window, you can create new

project components, open or rename existing components, or remove

components from your project. When the Project window is active,

menu options and buttons are available that let you perform additional

operations on the project and its components.

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# Shapefiles

Shapefiles are ArcView’s own format for storing features and

attributes. You create shapefiles by converting other spatial data

sources, by drawing shapes in themes you create, or by using tabular

data containing location information. Shapefiles usually come with

three files whose extensions are named .shp, .shx and .dbf. Without

any of these files, themes will not be displayed. Shapefile file

extensions and their functions are:

File

extension

Functions

.shp the feature geometry

.shx an index to the feature geometry

.dbf the associated dBASE file of attribute

information

# The Add Theme dialog box

Click “Add Theme” button . The Add Theme dialog box lets

you add a theme from a feature data source by default. Double-

clicking on the name of the data source adds it to the current view as a

theme. By holding down Shift, you can select and add more than one

data source at once. In case the themes are too many, you can stop

listing all themes by entering ESC key.

You can also add image themes by selecting Image Data Source

in “Data Source Types:” dropdown list in the lower left.

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You can edit shapefiles in features as well as in attributes. Data from

other sources may be edited as well by converting them to shapefiles

even though data itself is not editable.

Shapefiles are editable; From Theme menu, “Start Editing” is enabled.

Coverages are not editable; From Theme menu, “Start Editing” is

disabled.

# The Table of Contents

Table of Contents gives you the information of themes such as file

names and feature types. In shapefiles, each theme contains one

feature type unlike Arc/Info coverages. You can turn on or off themes

by check or unchecking the check box next to the theme’s name. The

order in which themes are drawn on a view is based on the order they

appear in the Table of Contents. You can change the order a theme is

drawn in. For example, polygon may cover up line or point, so you may

need to put the polygon theme down to the bottom. Just drag the

theme up or down in the Table of Contents. You can remove themes.

You can copy a theme and paste into other view.

Suppose you want to use “identify” tool to find out which attributes are

associated with a certain feature in the view. Before using this tool,

you need to set the active theme. The operations you can perform are

required to know which theme they work on. Making a theme active is

just as easy as clicking on the theme’s name in the Table of Contents.

The active theme will highlight. Now you can perform any operation

such as select, identify, find, and query builder over the active theme.

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Exercise: 3 Thematic Mapping-2

Aim: Choosing a Legend and Symbol

Choosing a Legend

With GIS, you can create maps based on the attributes of your

interest. Good thematic maps should meet intended purposes, as well

as convey the message effectively.  The ArcView Legend Editor lets

you choose thematic map types as well as map symbols.

#  Legend Types

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To create a thematic map, you should first select the active

theme by clicking the theme name in the Table of Contents. Legend

editor is open either by double-clicking the active theme in the Table of

Contents or by clicking Legend Editor button . Now take a close look

at the Legend Editor. Legend Editor shows the active theme on the top.

Legend type allows you to choose what types of thematic maps you

want to make. The list of available legend types is different depending

on feature types. For example, polygon feature type does not support

“Graduated Symbol”(feature size), but support Dot density map which

is not supported in line and point feature type. In the example below,

the feature type is polygon as shown in the shapes under the heading

of Symbol.

Single Symbol

All the features in the theme are displayed with the same colors

and symbols. This is useful when you only need to show where a

theme’s features are located.

Graduated Color

Features are displayed with the same symbol type, but the shade

(e.g., dark blue to light blue) or similar color (e.g., warm tone, cold

tone) represents the progression of values for a data attribute you

specify.

Graduated Symbol

The features are displayed with the same colors and symbols,

representing a progression of values. This is the best way to symbolize

data that expresses size or magnitude. Graduated symbol is only

available for point and line data.

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Unique Value

Each unique value in a theme is represented with a unique

symbol. This is the most effective method for displaying categorical

data. Unique Value lets you create qualitative thematic maps.

Dot Density

The features of a polygon theme are displayed with a number of

dots corresponding to a value. This method is good for showing how

particular things are distributed throughout an area. For instance, a dot

map depicting population will most likely have the strongest

concentrations of dots along rivers and near coastlines. Dot density is

only available for polygon data.

Chart

The features are displayed with a chart. The components of the

chart correspond to data attributes you specify, and the size of each

part in a chart is determined by the value of each data attribute. You

can specify whether the charts are pie charts or column charts. This is

a good method for displaying the values of many attributes.

# Choosing an Appropriate Legend

ArcView's Legend Editor helps you make a visually appealing

map that communicates your data to your target audience. You only

need to know a little bit about the data you wish to map.

Is your data categorical, like names of places or types of roads?

Use the Unique Values Legend Editor.

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Is your data ranked, like best sales territory to worst sales

territory?

Use either Graduated Symbols or Graduated Colors as

these types of legends are best suited to show a progression of

data values. However, if your data is qualitative, Unique Values

may also be appropriate.

Is your data raw count, like population or barrels of crude oil?

For polygon data, your first choice of legends should be

Dot Density. If you have point or line data, then use a Graduated

Symbols legend. If you use a Graduated Symbol or a Chart

legend you may also want to consider normalizing your data’s

values to make your legend easier to read.

Is your data normalized, like percentage data or population per

unit of area?

For polygon data, your first choice of legends should be Graduated

Colors. If you have point or line data, then use a Graduated Symbol

legend. If you need to show several normalized attributes, consider

using the Chart legend.

When a map type is chosen, ArcView automatically checks

through fields of an active theme whether they are categorical (field

type is usually character indicating the code) or numeric, and then

filter the fields depending on the map type chosen. (To find out,

compare the fields available when a quantitative thematic map (e.g.,

graduated color) is chosen, to those when a qualitative thematic map

(e.g., unique value) is chosen.) ArcView guides you to choose the right

type of field suited for map types. When creating quantitative thematic

maps such as graduated color, and graduated symbol, the data is

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classified into the manageable number of groups using natural break.

You can try other classification methods (e.g., quantile, standard

deviation), as well as change the number of groups, and ranges for

each group.

“Unique Value” allows you to choose categorical attributes (e.g.,

Sumlevel) as well while “Graduated Color” allows you to choose

numeric attributes only.

Choosing a Symbol

To open the Symbol Window, choose Show Symbol Window from

the Window Menu. Or alternatively when legend editor is already open,

double-click the shapes under the heading of Symbol in the Legend

Editor. ArcView’s Symbol Window contains five palettes (Fill, Pen,

Marker, Font, and Color), and a Palette Manager for customizing

palettes.  The first four palettes (Fill, Pen, Marker, Font) are used to let

you choose symbol suited to each feature type (polygon, line, point,

label respective). On the contrary, Color Palette is used to assign color

to any of those feature types.

# Fill, Pen, Marker, and Font Palette

With Fill Palette, you can choose how to fill the polygon (e.g.,

color-filled, empty, pattern-filled). With Pen Palette, you can choose the

pattern for the line (e.g., solid, dashed, double). With Marker Palette,

you can choose the marker suitable for the point theme (e.g., basic

shapes such as point, rectangle, triangle, and conventional symbol

such as school, church, hospital). Font Palette lets you select a font to

draw the label.  If you scroll the list of font available, you can find there

is ESRI font. The font set allows you to create the marker so that you

can work on more marker. To load additional marker, just select ESRI

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font (e.g., ESRI cartography) from the font list, and then click “Create

Marker” button at the bottom.

# Color Palette

Color Palette lets you select color for polygon, line, point, and text.

Color dropdown list shows the foreground by default. Since point and

line do not have area (less than one dimension), changing color to

point and line does not have to specify Background and Outline. That is

to say, Background and Outline only applies to polygon features. Text

only applies to labels. Sometimes you need to display polygon features

in transparency so that the feature may not block other features. To

display transparent polygon, set Background to nothing while

Foreground is set to pattern-filled.

Using Palette Manage will also let you meet your customization

needs such as loading existing palette files (“.avp”), importing image

files to markers, and saving current palette as a new file.

# Auto-Labeling Themes

Labeling themes makes users easier to identify features. To label,

select Auto-Label from the Theme menu after making a theme of your

interest active. Then select the field to be used for labeling. The default

is that a text size is dependent on map scales, and overlapping labels

are automatically removed.

Auto-labeling labels all features when no features are selected. When

features are selected, labels will be drawn only for the selected

features. You can change font and size of labels using Font Palette in

the Symbol Windows.

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Exercise 4: Creating a Layout and working with it

Aim: Creating a Layout and working with it

A layout is a map that lets you display views, charts, tables, imported graphics, and graphic primitives. The layout is used to prepare these graphics for output from ArcView.A layout defines what data will be used for output and how they will be displayed. A layout can be dynamic because it allows you to make specific graphics live. When a graphic is live, it reflects the current status of the data. For example, if the data in a view changes, the layout automatically reflects the change.

The same data can be displayed on a number of different layouts. Think of each layout as being a different way of presenting the data. If you are doing a marketing presentation you will probably want to present data differently than if you are doing cartographic production. With ArcView, a different layout of the data can be created for each application. Using Avenue you can extend the power of ArcView by creating custom functions, user interfaces and cartographic templates that will assist you in creating output.

What a layout can containThe Layout provides the standard graphics and operations one would expect in a typical 'drawing' package.

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These graphics are drawn using the Draw tools and include points, lines, polygons, rectangles, and circles.The Layout also contains objects specific to the ArcView environment, including frames containing ArcView views, charts, and tables, and ancillary objects such as legends and scale bars.

Printing layoutsYou can print a layout or export a layout to a number of formats to use with other software packages.

Working with layouts

An ArcView project can contain any number of layouts.

To see which layouts are in a project

Click on the Layouts icon on the Project Window. The layouts in the current project are shown in the list.

To create a new layout

With the Layouts icon selected, click the New button at the top of the Project window. ArcView creates a new layout and its name will appear in the list of layouts in the project. ArcView names new layouts in numerical order: Layout1, Layout2, Layout3, etc. See Overview of creating a layout. You can also double-click the Layouts icon to create a new layout.

To open a layout

Double-click the layout's name in the list of layouts in the Project window, or select the layout's name and click the Open button.

To close a layout

From the File menu, choose Close, or click the close option on the layout's window (This option varies according to the GUI you are using).

To rename a layout

Click once on the layout in the list in the Project window and choose Rename from the Project menu. A layout's name is also a layout property you can edit.

To save the work you do with a layout

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In ArcView, you save the work you do with any project component by saving the project. To save your project, choose Save Project from the File menu or click the Save Project button . See Saving your work.

To copy a layout from one project to another

If you want to copy a layout from another project into your current project, you should import the other project into your current one using Import on the Project menu. This will copy all the components of the other project into your current project. You can then delete the components that you don't require using Delete from the Project menu.

Overview of creating a layout

You create a layout from the components in your project such as views, charts, and tables. You can also draw various graphics on the layout too.

Open or create a project

If you have not yet opened a project, choose Open Project or New Project from the File menu to either open an existing project or create a new one.

Create a new layout in your project

On the Project window select the Layouts icon and then press the New button. A new layout will appear in your project.

Define the layout page

Before you begin adding things to the layout, you should define some of its characteristics like units, page size, orientation and margins.

Add a view

To create a map for output containing geographic data you must first add a view to your layout. When you add the view you can choose to make it live linked. This causes any changes in the view to be reflected in the layout. If you decide not to live link your view, it will not change in the layout even if you make changes to the view.

Add a legend

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After adding a view you can add a legend to the layout. The legend will show the symbology for the themes that are displayed in the view.

Add a scale bar

There are a number of different styles of scale bars supported by ArcView. After you select a view to associate the scale bar to, you can select the type of units, interval values and number of intervals that the scale bar will have.

Add a title

When you are satisfied with the geographically based parts of your layout you can add a title to it.

Create graphics

If you need to add any graphic (points, lines, circles, etc.) you can do so.

Add other graphics to the layout

There are a number of additional "standard" graphics you can add to your layout. You can place both ArcView tables and charts on the layout if so desired in your output product. You can also choose from a provided list of north arrows, or import a file from a another graphics package into the layout.

Arrange the layout graphics as needed

When all of the graphics you want are present in the layout you can use a number of different tools to arrange them as needed. Among the actions you can perform on layout graphics are the following: align, bring to front, group, etc.

Assign patterns, colors and fonts to the graphics

By double-clicking any graphic in the layout you can change its properties. In the case of a view or legend, you will see a properties menu. For any graphic primitive you will see ArcView's Symbol Window.

Print the layout

When you are finally satisfied with your layout you can send it to a printer.

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Exercise 5: Working with tables

Aim: Quering a table

An ArcView project can contain any number of tables.To see which tables are in a projectClick on the Tables icon in the Project window. The tables in the project are shown in the list.To open a table

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Double-click the table's name in the list of tables in the Project window, or select the table's name and click the Open button.To open a theme's table

1 Open the view containing the theme.2 Click on the theme to make it active.3 Click the Open Theme Table button in the View button bar.

When you open a theme's table, it will appear in the list of tables in the Project window in which case it can also be opened using the Open button on the Project window, as described above.

To identify a record in a table

1 Click on the Identify tool in the Table tool bar.2 Click on the record you want to identify.

When you identify a record, the results are displayed in a dialog box. This dialog box is also used to display the results of subsequent Identifies.This tool is useful if you want to compare two records that are at different ends of a table.

To find a record in a table

1 From the Table menu, choose Find, or click the Find button .2 Type in the attribute value you wish to find. Find works by searching the features to find the first feature with the value you specified, in any of its text attribute fields (i.e. fields containing text strings as opposed to numeric values). Find doesn’t search in numeric fields. You don't need to enclose the text you specify in quotes. Find is not case-sensitive. You can enter part of the text. For example, just typing Afgh will also find Afghanistan. Wildcard characters are not supported by Find.

3 Press OK. Find will search the table to find the first record with that attribute value.

To find the next record that matches the specified value

1 Choose Find again. The attribute value you previously specified will still be shown in the Find dialog box.2 Press OK. Find will search the table to find the next record with that attribute value.

Selecting records with the mouse or keyboard

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The Select tool can be used to select one or more records from a table.Use Find to select a particular record in a table quickly.

Selecting records using a query

Use the Query Builder when you want to select records according to their values. For example, you can build a query to select all the records in which the value for a field named Price is greater or equal to $1000. You can also build more complex queries.You can also use the Query Builder to narrow down your selection from the set of records that is already selected, and to add additional records to this set.Selecting records in a table by selecting features on a view

When you are working with a theme's table, selecting or deselecting the theme's features in the view also selects or deselects the records for these features in the table. See Selecting features on a view.Selecting records using a chartA chart contains one data marker for each selected record in the table. By erasing data markers in the chart you can deselect records in the table. In this way you can use the chart to focus in on particular records of interest. See Adding and erasing data markers on a chart.

Switching the selected and unselected sets of recordsUse Switch Selection if you, for example, want to select the records that are not in the top 5 rows in the table, you could use the mouse to select records in the top 5 rows, and then switch the selection.Clearing the selected recordsChoose Select None to deselect the selected records in a table.Selecting all the records in a tableChoose Select All to select all the records in a table.

To display the selected records together at the top of the tableClick the Promote button . See Displaying the selected records in a table.

Getting statistics about a table

Use the Statistics option from the Field menu to obtain statistics about a particular field's values in a table. Statistics displays information for either all records or the currently selected records. You can only perform statistics on numeric fields. The following statistics are reported:

Sum

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CountMeanMaximumMinimumRangeVarianceStandard deviation

Summarizing a table

You can summarize a table based on a particular field's values. The results are stored in a new table. If some records in the table are currently selected, only these records are summarized. If no records are selected, the whole table is summarized.Summarize creates one record in the new table for each unique value of the field you chose. Each record contains a count showing how many records in the table being summarized have this value. Each record also contains the result of any summary statistics you requested in the Summarize dialog box, such as the sum, minimum. maximum and standard deviation for any other field in table.

Examples

The table for the USA data source that comes with ArcView has a field called Sub_region. You can summarize the States table on this field to generate summary statistics on a regional basis. Let's say you want to find the total population in each region, In this example, the population field used has been joined to the theme's table with Join between steps 3 and 4:

1 Open a new view and add a theme to it representing the USA data source.2 Click on the theme in the Table of Contents to make it active.3 Click the Open Theme Table button .4 Click on the field called Sub_region to make it active.5 Click the Summarize button .6 In the Summarize dialog box, choose Pop1990 from the Fields list, Summary from the Summarize by list, and then press Add, then press OK.

7 ArcView creates the summary table and displays it. The summary table shows the total population of each region in the USA, and the count of records in the theme's table that represent states in each region.

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Creating a summary table and then joining it to the table of a theme is a useful way of adding statistical data to your view.

For example, you have a dBASE table containing a list of your customers and their addresses, and want to make a map of the US with each state shaded according to how many customers are located there. Here's how you can make this map:

1 Open a new view and add a theme to it representing the USA data source.2 Add your dBASE table of customers to the project.3 Click on the field in the table of customers that contains the state name to make it active.4 Click the Summarize button .5 Press OK on the Summarize dialog box. Summarize will automatically create a summary table containing one record for each state named in your table of customers, along with a Count field showing the number of customers in each of these states.

6 Open the feature table of the USA theme.7 Join the summary table to the States theme's table, using the state name field as the common field.8 Edit the legend of the States theme to classify the states according to the value of the Count field.

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