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  >  Docs Center  >  Using ENVI  >  DEM Extraction Module  >  Set Output DEM Projection

Set Output DEM Projection

Set Output DEM Projection

Step 7 of the DEM Extraction Wizard allows you to set parameters for the DEM output projection and map extents. You have the option to change parameters such as the output projection type, pixel size, or output image size.

The Output Projection and Map Extent shows the Upper Left Corner Coordinate map projection and Eastings and Northings of the upper-left corner of the output DEM projection. You may want to change the point defined as the Upper Left Corner Coordinate of your output projection, based on your own knowledge of the overlapping region in your output projection.

  1. To change the Upper Left Corner Coordinate, type in the new map coordinates in the Eastings and Northings text fields, and press Enter.
  2. You can change the Eastings and Northings fields to Latitude and Longitude map coordinates by clicking the toggle button next to the map projection.
  3. To change the projection, click Change Proj. Select a new projection from the list in the Projection Selection dialog, click Units, change the units as desired, and click OK. The values of the map projection X and Y Pixel Sizes are changed to reflect the new units and projection.
  4. The x and y post spacing (X Pixel Size, Y Pixel Size) for the output projection is dictated by the input projection chosen. You may want to adjust the values for the x and y post spacing, or you may want to change the units of these values.
  5. To change the X Pixel Size, enter a new value and press <Enter>. Repeat for the Y Pixel Size. When you change these values, the Output X Size and Output Y Size values also change.

  6. The Output X Size and Output Y Size values describe the output DEM size in pixels. This is the overlapping region of your output projection. You may want the output projection size to be different from the output values shown. Change the Output X Size by typing a new value and pressing <Enter>. Repeat for Output Y Size.
  7. There are six options available from the Options drop-down list:

    • Report output size in Pixels: Sets the Output X Size and Output Y Size units in pixels (default).
    • Report output size in Meters: Sets the Output X Size and Output Y Size units in meters.
    • Maintain map extent when pixel size changes: Automatically adjusts the number of rows and columns (Output X Size and Output Y Size) to maintain the map extent (default).
    • Maintain output pixels when pixel size changes: Maintains the Output X Size and Output Y Size, even if the X Pixel Size or Y Pixel Size changes.
    • Restore initial values: Performs an undo of any changes made to the settings in this Wizard step. This resets the Step 7 settings to the default settings.
    • Match existing file: Allows you to use the map extent from an existing file.
  8. Click Next to continue.



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