Global Mapper Pro

Splitting Polygons?

Roger Edrinn
Roger Edrinn Global Mapper UserTrusted User
edited April 2012 in Vector Data
Is there a way for GM to split large polygons? I'm aware of cropping, but that deletes one of the pieces, or did.

Turns out multiple large layered polygons (100's of sq mi) create display anomalies in Garmin binary.

My simple minded solution is a follows:
  • Convert polygon to line
  • Add one or more lines in the center
  • Join the lines to make an enclosure
  • Convert line to polygon
Bit tedious.

Did a search, found 3 threads on merging polygons, none on splitting.



  • global_mapper
    global_mapper Administrator
    edited April 2012
    There is a relatively new option to split area features against a line. See for details. I think this will do what you are after.


  • Roger Edrinn
    Roger Edrinn Global Mapper User Trusted User
    edited April 2012
    Looks good, will give that a try. Thanks

    There is a relatively minor error in your help text:
    You can split selected area features to a selected line feature by right-clicking and selecting the option to Crop Selected Area to Selected Line. This will split the area feature along the selected line boundary. If the line doesn't extend all the way to outside the area, it will be extended to the area bounding box. Note that the original area will remain available as a deleted feature, so you can recover the original line if needed.
    Believe that should read area.
  • global_mapper
    global_mapper Administrator
    edited April 2012
    Thanks, I'll get the typo fixed for the next help update.
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