I have a polygon in QGIS consisting of a dissolved set of shapes. My objective is to split this shape using the lines from a set of Voronoi polygons.

enter image description here

To do this I calculated the Voronoi polygons, and used the polygon to line tool to extract the outlines. Next my plan was to use the integrated "Split With Lines" tool to split this polygon along the lines as shown in the image.

When I try this though, the algorithm seems to get stuck and just shows processing without ever arriving at a result. I cancelled the previous attempt after waiting for almost 30mins. Is there a reason this process takes longer than I'm expecting? Is there another way to do this I could try?

  • The polygon looks like it is a multipart. You might try using the multipart to singlepart tool and then splitting the resulting polygons.
    – John
    Commented Jan 20, 2022 at 16:45
  • 1
    Or possibly convert lines to polygons and then use intersection
    – Matt
    Commented Jan 20, 2022 at 17:56
  • The second solution worked, thank you!!! In regards to the first comment, you're right it was a multipart, but when I tried your method it still got stuck for some reason... Happy to confirm the answer if you want to post it quick
    – najusten
    Commented Jan 20, 2022 at 18:32

2 Answers 2


For me the verified answer didn't work. I found a different solution if it's no problem if your polygons don't exactly touch:

  • Buffer your lines with an insignificant amount (I chose 0.01 meters).
  • Use difference between your input layer and the buffered layer.

Convert the lines to polygons and then use the intersection tool.

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