I have a 3000 mile long line that has quite a few gps errors where the line self intersects itself. Mapshaper does the best job of all the tools identifying these intersections on import, QGIS's intersections tool does not identify them.

I can't find anything in the commands or documentation of how or where it stores the points it identifies as these intersections. I would like to export the points to be able to fix the errors. Fixing them in mapshaper causes to much simplification to the line itself in other areas.

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1 Answer 1


You may have used the tool that generates nodes for intersecting features on different layers. For what you describe Vector -> Geometry Tools -> Check Geometry Validity may work for you. While you may not export the intersections points directly, you will be able to copy and paste in a text file or other editor. The coordinates of the intersections are generated.

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And there are probably a few ways you could get the nodes of the line itself exported to a csv file. One very simple way is to use the MMQGIS plugin.

  • The Check Geometry Validity Tool never finishes running on my geometry but I recognize that this is a better solution that trying to work in mapshaper. Haven't found the issue with my particular geometry as to why it crashes the tool yet but I will keep digging. Dec 11, 2017 at 18:13
  • That's nice of you to accept my answer as a solution even though it did not get you all the way to your goal. Could be your line is 3D and mine is not ... just speculating. Please post your solution when you figure it out.
    – ZrSiO4
    Dec 11, 2017 at 18:45

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