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Extract a DEM

Extract a DEM

Select Topographic > DEM Extraction > Extract DEM from the Toolbox. This menu option provides an alternate way to generate a DEM without using the DEM Extraction Wizard.

  1. From the Toolbox, select Terrain > DEM Extraction > Extract DEM. The Select Left Stereo Pair Image dialog opens.
  2. When you click OK in the Select Right Stereo Pair Image dialog, the Select Input Tie Points File dialog opens.
  3. Navigate to the directory and filename where the tie point information is stored. (See Select Stereo Tie Points for information about selecting tie points and saving them to a file.) Click Open. The Extract DEM Parameters dialog opens.
  4. In the Extract DEM Parameters dialog, set the following parameters:
    • Epipolar Reduction Factor: This controls the down-sampling of the output epipolar image size. This factor is a floating-point value with a minimum of 1.00 (the default), which determines the lowest image pyramid level on which image matching can be performed. A value of 1.00 means the epipolar images have the same resolution as the input images. A value of 2.00 means the epipolar images have half the spatial resolution as the input images.
    • Extract DEM Parameters and Extract DEM Result: See Select DEM Extraction Parameters for detailed information about these settings.
    • Stereo GCP File: This allows you to load a pre-existing GCP file. Click Select GCP File. The Select Input GCP File dialog. Navigate to your GCP file and click Open.
    • Extract DEM Projection and Size: See Select DEM Extraction Parameters for detailed information about these settings.
  5. Click OK to proceed. The Epipolar images and parallax images are created, the DEM posts are built, and the DEM is geocoded before the DEM appears in the Layer Manager.
  6. You can now view the DEM by loading it into a display group. You can also perform any editing on the DEM using the DEM Editing Tool.



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