Global Mapper v25.0

problem combining polygons

JSL Global Mapper UserTrusted User

I had a circular polygon that I split, then added terrain data to each half. However, when I tried to combine the two halves, one disappeared. I checked for invalid areas, but there weren't any. Any idea why one half would disappear upon combining?

Polygons before combining:

Checking for invalid areas:

After combining:


  • JeffH@BMG
    JeffH@BMG Global Mapper Developer Trusted User

    Hi JSL,

    I can reproduce what you're seeing. It's a bit of a mystery, as the two polygons do indeed intersect at their boundaries, so they should combine correctly. Unfortunately, I can see that when we combine them internally, no result is generated, so we keep the original area feature and move on, which is what you're seeing.

    I'm not sure what version of Global Mapper that you're using, but it must be relatively recent. If so, you should see a "Use legacy method" checkbox on the "Select Combine Options" dialog. This uses the original Combine code, which we replaced with a much faster implementation, but kept around for situations like this. When I checked "Use legacy method", the polygons combine as expected.

    In the meantime, I created a new issue (GM-14338), so we can take a closer look.

    Thanks for reporting this.


  • JeffH@BMG
    JeffH@BMG Global Mapper Developer Trusted User

    Sorry, the issue is actually GM-15080, just for the record.