Adjust to geoid
Adjust to geoid command applies an elevation correction to images of the active image list. This command is often used to transform the WGS84-based ellipsoidal elevation values to a geoid-based height model.
The input model for elevation adjustment can be provided in different ways:
•Points from file - text file containing space-delimited X Y dZ points.
•TerraModeler surface - triangulated surface created from X Y dZ points. The model must be loaded in TerraModeler. This has the advantage that you can visualize the adjustment model.
•Selected linear chain - linear element which has vertices derived from X Y dZ points.
The first two input models utilize aerial interpolation while the last input model uses linear interpolation along the linear element’s segments in order to derive adjustment values.
To adjust image elevations to a geoid model:
1. (Optional) Load a geoid model into TerraModeler.
2. Select Adjust to geoid command from the Images pulldown menu.
This opens the Adjust to geoid dialog:
3. Select the input model type in the Dz model field and click OK.
If Points from file is selected as the Dz model, the Geoid dz file dialog opens, a standard dialog for opening files.
4. Define the text file that contains the geoid coordinates and elevation differences and click Open.
This applies the elevation adjustment to all images of the active image list. An information dialog shows the minimum and maximum values of the adjustment.