Raster Spatial Operations
Select IMAGE PROCESSING → PALETTE → RASTER SPATIAL OPERATIONS in the main menu.
Input Layers:
Select the first layer in the upper selection field.
Select the second layer in the lower selection field.
Only Visible Area: click on this box if the process is to be done in the visible area.
Spatial Operation: Select one of the three formats:
Aggregate Area:
Adds a new area to the polygon.
Remove Area:
Remove a determined area from
the polygon.
Unite polygons:
Attach two or more polygons
keeping the attribute of one of them.
Output Layer Name: enter the name of the resulting image.
Projection: click on this button to open projection window to adjust its parameters.
Resolution: enter the values for X and Y axis resolution.
Click on the OK button.