Using an inclusion mask, exclusion mask, or both

A mask limits the input data to process. That is, a mask can define one or more areas to include, such as the pixels under the inclusion mask. For example, when you are interested only in changes in a specific area, you can use an inclusion mask to limit the change detection to that area.

Alternatively, you can use a mask to exclude one or more areas. That is, pixels under the mask are not processed. For example, you can use an exclusion mask over a water body if any variations in pixels in that area are of no interest.

A pixel can be covered by both an inclusion mask and an exclusion mask, in which case the pixel is excluded. This can be useful in certain scenarios. For example, suppose you want to limit processing to a particular area, but changes in water bodies are of no interest. In such a scenario, you would specify your area of interest as your inclusion mask, and then your water layer as your exclusion mask.

Note: After you create a change layer that produces a satisfactory result, save it for future use. To do this, right-click the change layer on the Map tab in Focus, and then click Save As.

To use an inclusion mask, exclusion mask, or both

In the Change Detection window, click the Masks tab (if it isn't the active tab).
To use an inclusion mask, select the Inclusion mask check box, and then do the following (otherwise, proceed to the next step):
- Type the full path and file name of the file you want to use as a mask in the File box, or click Browse to select the file.
- In the Layer list, click the bitmap layer or vector segment you want to use as a mask.
- If you specified a vector layer that already has selected shapes in Focus, you can further refine the mask to use only those shapes by selecting the Use selected shapes only check box.
  Note: Pixels outside of the inclusion mask will be set to NoData.
To use an exclusion mask, select the Exclusion mask check box, and then do the following (otherwise, proceed to the next step):
- Type the full path and file name of the file you want to use as a mask in the File box, or click Browse to select the file.
- In the Layer list, click the bitmap layer or vector segment you want to use as a mask.
- If you specified a vector layer that already has selected shapes in Focus, you can further refine the mask to use only those shapes by selecting the Use selected shapes only check box.
  Note: Pixels outside of the inclusion mask will be set to NoData.
Click Run.