Splitting Polygons

tleetlee Global Mapper UserPosts: 4
edited September 2012 in Technical Support
Hi

I am trying to find out how to split an existing polygon into two new and separate polygons. I have done a search and come across the following thread, but can’t follow the instructions (http://www.globalmapperforum.com/forums/vector-data/7941-splitting-polygons.html) or it is not working for me.

The suggested solution is to select the two vertices – I am not sure what this means. The right clicking and selecting “Split Selected Area at Selected Vertices”. I haven’t been able to find this menu option.

I have tried selecting the digitizer tool, then selecting my polygon and line together holding down control. Then right clicking. I then select “Crop/Split Line Feature to Selected Area Feature” (the closest to the above instruction). I then select “No” to split lines. Nothing happens.

Does anyone have any advice please? What am I doing wrong.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2012
    You need to turn on vertex display (Shift+V), then you can select a vertex on each edge. If the vertices aren't displayed you can't select them.

    Another option is to draw a line feature that you want to crop to. Select that line and the area with the Digitizer Tool, then select the Crop/Split submenu option to crop the area to the selected line.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • tleetlee Global Mapper User Posts: 4
    edited September 2012
    I've tried the second option as it is relevant to how I want to do it in practice - the line will have been GPS'd in the paddock (eg. for progress of timber harvesting) and the polygon might be my mapped plantation area that is currently being harvested. So this would give me my harvested area and standing plantion area.

    However, following your instructions above doesnt work for either the "Yes - Crop" or "No - Split" option. I use control to select both the line and polygon, but no good.
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited September 2012
    What version are you using? The option to create areas to selected lines is only available in recent versions. If I select both an area and a line, there is a 'Crop Selected Area(s) to Selected Line' option available on the Crop submenu of the right-click menu.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
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