Making 3D Maps with the 3D Analyst Extension

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Making 3D Maps with the 3D Analyst Extension

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

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3D data

• In addition to x,y, add z (elevation) data
• DEM digital elevation model file format
  available from U.S. Geological Survey
• Grid a matrix of values ArcView file format
  can add as a theme
• TIN triangulated irregular network ArcView
  file format can add as a theme

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3D data available from the state

• nris.state.mt.us/nsdi/nris/el10/dems.html
• Four maps for each lat, lon a,b,c,d
• Westernmost tip of Mineral County 115, 47, Map c

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Prepare to add USGS DEM data

• Unzip the file d47115_c.zip to d47115_c.dem
• From the File menu, select the Extensions command
• In the Extensions dialog, check3D Analyst

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Import the DEM file

• From the File menu, select the command Import
  Data Source
• In the Import Data Source dialog, select the
  type USGS DEM
• Click OK

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Import the DEM, create the grid

• Specify the DEM filename d47115_c.dem
• Specify the name for the grid (one convention
  appends _grid to the name d47115c_grid

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Add and view the grid theme

• Click Yes when prompted to add the grid as a
  theme
• Its default legend uses the equal interval
  setting helpfile suggests using equal area for
  elevation data

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Convert grid to triangular irregular network (TIN)

• Select the grid in the table of contents
• From the Theme menu, select the command Convert
  Grid to TIN
• Specify the filename (d47115c_tin)

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Add the TIN as a theme

• Specify the z-value tolerance (here, default)
• Add the TIN as a theme

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Create a common legend for the TIN themes

• When using multiple DEMs, can create a common
  legend to hide the seams

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Lay themes on top

• Activate the themes to appear on top of the
  landscape
• From the Theme menu, select Convert to 3D
  shapefile
• Select Surface
• Select a TIN as the underlying surface

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Add the 3D shapefile

• Specify the name for the 3D shapefile (this
  convention uses the original theme name and the
  surface theme name)
• Add the shapefile as a theme to the view, click
  Yes

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View the 3D Scene

• From the View menu, select the command 3D
  Scene
• In the 3D Scene dialog, select Themes and
  click OK
• Can also add as an image themes are more
  flexible (can add or remove independently)

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The 3D Scene

• The 3D scene has a table of contents (TOC) like
  the View
• Theme legends
• (Superior area, from the south)

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The project lists all 3D Scenes

• 3D Scenes appear in the project table of contents
• Can name the 3D scene using the properties dialog
  (just as you can name views or themes)

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Navigating in the 3D Scene

• Choose the navigate tool (the ship) ,
  press a mouse button, and drag the mouse to move
• To rotate hold down the left mouse button, move
  the mouse left or right
• To zoom in hold down the right mouse button,
  move the mouse towards you
• To zoom out hold down the right mouse button,
  move the mouse away from you
• To pan hold down both mouse buttons, move the
  mouse (if 3-button mouse, use the center button)

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Superior area (from the west)
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Superior area, from the SE

• Points, roads appear on the surface
• Yellow points homes assessed summer 2000
• Up Flat Creek, Cedar Creek, Trout Creek