Procedure Library for Projecting Digital Elevation Models in Arc/Info

The purpose of this procedure library is to explain how to project a USGS DEM from one projection to another. This example will use the projection of UTM to State Plane. By projecting the DEM into State Plane 1927, we will be able to use it as a base layer for our existing coverages.

Note: % denotes an Arc command prompt.

Andy Freed

5/25/01

Tools: ArcView 3.2, Arc/Info/Tools, Kerry Leageux.

Convert DEM to Grid:

· Open ArcView GIS

· Load Spatial Analyst extension, and 3D Analyst extension (for later).

· Select File/Import. The dialog box will allow you to select the file type. Choose USGS DEM and find the dem you want.

· Name the output grid and assign a location.

· Click OK.

Open Grid in Arc

· Open Arc (Start/Programs/ArcInfo User 7.2/Arc)

· Set the working directory: % w d:/temp/Q523

· List all grid files: % lg

· Start Arctools: % arctools

Open Command Tools

· From the popup window select Command Tools and click OK.

· From the Command Tools menu select Edit\Coordinates\Project Coverage

Project Cover

· Set Geo-Dataset type to Grid

· Right Click on the Input Cover dialogue box, and select the grid you want to project.

· Click on the Define button and choose Other for the geographic extent.

· Select UTM

· Select Specified Zone for the UTM popup dialogue, select the zone of coverage. (10)

· Set the Datum to NAD27

· Units should be in meters, and sphereiod should be Clarke1866.

· Choose options and select Z unit as meters (elevation)

· Click Ok.

· Click Ok

Set Output Projection

· Set name for the output in the Output Grid field.

· Click define to set the projection of the output type.

· Click on the Define button and choose Other for the geographic extent.

· Select State Plane

· A popup window will let you select the State Plane Zone. Right

· Right click on the dialogue box to select the zone from a list. (Washington North)

· Set the Units to US Feet, and the datum to NAD27

· Click options and set the Z units to feet.

· Click OK

· Leave output Grid cell size empty to preserve units.

Project Grid

· Click Apply and wait for the projection to complete. This will take several minutes.

Close Arctools.

Open in ArcView

· In the Table of Contents, select 3D scene.

· Click the Add data button.

· Set file type to Grid and select the file you output.

· A flat image will appear in the scene.

Convert to 3D TIN

· Select Convert Grid to TIN from Theme menu.

· Select location for file and name it.

· Add to 3D scene.

For additional information, see ArcView or ArcInfo help.

Modified: 5/25/01