Updating elevation values under a vector mask

After you create a polygon-mask layer, you can apply one or more operations to update the elevation values under the selected polygon.

To adjust areas under the polygon

In the viewer, with the DEM Editing Polygons layer active, select a polygon to which to apply an operation.
You can only apply an operation to a single polygon. If more than one polygon is selected, the Operation list in the DEM Editing window is unavailable.
In the DEM Editing window, in the Operation list, click the operation you want.
For a description of each of the avilable operations, see DEM editing operations.

Depending on the operation you select, you may need to enter or select additional information. That is, additional options, such as boxes, check boxes, and so forth will appear under the Operation list based on the operation you select.
To apply blending, select the Blend check box, where applicable, and then enter a value for the width of the blend (in pixels).
Blending reduces the appearance of seams by mixing the pixels values directly outside the polygon to achieve a gradual transition between the masked and unmasked areas. For example, a value of 5 will create a ramp of values from the mask edge to five pixels away.

By default, no blending is applied. When selected, the default blend width is 0, or the value specified previously.
If necessary, select the Apply blending subsequently check box to blend pixels under the active mask during future editing operations. If the active polygon represents an area that should not have a smooth transition between it and surrounding areas, such as a bridge, make sure the Allow Blending Subsequently check box is clear.
Do one of the following:
- To apply the selected operation to the active DEM, click Apply.
- To apply the selected operation to all of the previously edited values, click Apply with Overwrite.
For example, if you have already edited a series of buildings, and you want to smooth the area surrounding them, draw a polygon to encompass the buildings, and then apply a strong smoothing filter under the polygon by clicking Apply. By doing so, the buildings edited previously will remain unchanged.
To refresh the low-resolution ortho image preview, click Update Low Res. Ortho.
The low-resolution image preview in the viewer is updated, and you can visualize approximately how your DEM changes will affect the orthorectified images.

Note: The image displayed in the viewer is the preview image generated along with the DEM. This image is typically at a much coarser resolution than that of the actual orthorectified images. To view how DEM changes will potentially affect the full-resolution ortho images, you can work on a subset of the image using the Full Res. Ortho Preview window. For more information, see Using the Full Res. Ortho Preview window.