The DEM Extraction Wizard
The DEM Extraction Wizard walks you through nine steps to extract a DEM. The Wizard allows you to step forward, backwards, and to save the workflow at any step so that you can continue at a later time. The functionality provided in the nine steps is also available to run separately from the Wizard using the Topographic menu on the ENVI main menu bar. The Wizard workflow is illustrated in Figure 2-1, and the nine steps are outlined here.
Step 1: Selecting the Stereo Image Pair - Select the stereo pair, and supply the minimum and maximum elevation of the region.
Step 2: Selecting Ground Control Points - (Optional) Select the source for the Ground Control Point data.
Step 3: Viewing, Adding, Editing GCPs - Edit, add, and view GCPs. You can choose to read in a GCP file and edit it, or manually enter the GCPs in Step 2.
Step 4: Collecting Tie Points - Select the source of the tie points required for DEM extraction. You can have them automatically generated by the Wizard, load an existing tie points file, or choose to enter the tie points yourself.
Step 3: Viewing, Adding, Editing GCPs - Edit, add, and view tie points.
Step 6: Generating Epipolar Images - Create and save the left and right epipolar images.
Step 7: Setting Output DEM Projection - Set the projection system, the output DEM pixel size, and the number of rows and columns in the output.
Step 8: Selecting DEM Extraction Parameters - Define minimum correlation, moving window size and terrain detail, and specify where to save your DEM result.
Step 9: Examining the DEM Result - Display your DEM result. You may want to use the DEM Editing Tool to edit the displayed the result.
These workflow steps are described in more detail in the following sections.
