Adding And Displaying Themes

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Adding And Displaying Themes

• John Q. Murray
• Murray Information Services, Inc.

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Create a new project

• Launch ArcView 3.2
• It automatically asks whether to create a new
  project with a new View
• Click OK
• A project includes views, tables, layouts
• A view includes themes (aka layers, coverages,
  shapefiles)

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Create a view

• A view is a collection of themes (in a specific
  order) assigned units of measurement, symbols,
  labels

When you create a new Project with a new View,
ArcView 3.2 asks whether you want to add data to
the View. Click Yes
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Add a theme to the view

• 2 more ways to add themes
• From the View menu, select the Add Theme
  command,
• Select the Add Theme tool

From the dialog Add Theme For Data Source
Types select Feature Data Source Select
s\gisclass\county.shp
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The View with Montana counties
From ab143.zip, from the MT state GIS library At
first the theme is not visible Click on the
checkbox
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Themes Active / Visible

• Many operations require the theme to be active
• An active theme appears to be raised
• To make the theme visible, check its box in the
  Table of Contents
• Ct107 not visible, not active
• Hd43a visible, not active
• Countys visible, active
• Countysft not visible, active

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Add a point theme MT cities

• The largest city in each county from NRIS file
  ct107.zip
• From the View menu, select Add theme
• Select the theme s\gisclass\ct107.shp
• Click OK
• Check the theme

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The View MT counties, cities
On the left side, the Views Table of Contents
now lists two themes Ct107.shp and County.shp
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Add a line theme MT rivers

• This line theme contains major MT rivers from
  NRIS file hd43a.zip
• From the View menu, select the Add theme
  command
• Select hd43a.shp
• Click OK
• Check the theme

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The View counties, cities, rivers
On the left side, the Views Table of Contents
now lists 3 themes Hd43a.shp, Ct107.shp and
County.shp
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The View properties

• View properties can be viewed and changed
• From the View menu, select the Properties
  command
• Change view name to MyView
• Set Map Units to meters (These themes are in m)
• Set Distance Units to feet (For display)
• Click OK

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Distances displayed in feet

• After changing units, may need to reset view
• From the View menu, select Full extent
• Distance was miles
• Now is feet

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The Theme properties

• A Theme has properties that can be viewed and
  changed
• From the Theme menu, select the Properties
  command
• In the Theme Properties dialog, change the
  Theme Name to whatever you like

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The new theme name appears

• Here we change the theme name to mt-rivers.shp
• The new name appears in the table of contents
• Note that this does not change the name of the
  file

15
Save the project

• From the File menu, select the commands Save or
  Save As or the button
• In the Save Project As dialog, enter the
  project filename MyProject1.apr, then click OK

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Three types of themes

• Point individual points, such as homes,
  transmitters, power poles, etc.
• Line roads, streams, etc.
• Polygon property ownership boundaries city,
  county, state, nation boundaries, etc.

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Change the themes order

• Think of each theme as appearing on a sheet of
  transparent plastic
• You can change which sheets are on top of others
• In general, place polygons at the bottom, lines
  on top of polygons, and points on top of lines
• Drag them with the mouse

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Summary ArcView 3.2 file types

• Many programs use their own special files
• Example Word .doc files, Excel .xls files
• ArcView 3.2 has many special file types
• Some of the most frequently used
• .APR ArcView 3.2 project file
• .SHP shapefile theme
• .AVX ArcView 3.2 extension

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ArcInfo Coverages

• ArcView is a viewer with limited editing ArcInfo
  is the industrial strength expensive authoring
  version. ArcInfo file extensions in a coverage

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Save the project again

• Save early, save often
• ArcView 3.2 has a reputation for crashing
• Save your work so you dont have to do it all
  over again
• From the File menu, select the Save command