Monday, November 7, 2011

Clip a polygon with another polygon using Global Mapper

In GIS data editing work, it may be useful to clip a polygon with another polygon in a simple boolean operation. Global Mapper can perform the clipping task using the Cut Selected Area(s) from another Area (Add Islands) function. The example below illustrates a simple polygon clipping procedure:
  1. Start Global Mapper. Load or create at least two overlapping polygons.


  2. Press ALT+D.

    The Digitizer Tool is activated.
  3. Move the cursor to the polygon to be used as the clipper. Click on the polygon.

    The polygon is selected.
  4. Press the mouse right button anywhere in the map view.

    A pop up menu appears.

  5. Choose Cut Selected Area(s) from Another Area (Add Islands).

    The prompt appears: Select the Area to use as the Parent for this island, Esc to cancel.
  6. Move the mouse to the polygon to be clipped. Click on the polygon.

    The prompt below appears.
  7. Click Yes.

    The polygon is clipped.

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