I have feature with a big amount of vertices. But these vertices are totally useless and make Qgis editing too slow. Lets look on image with example:

These vertices inside of black line I want to delete. But I want to preserve shape of red line as well. So I need to let vertex outside of black lines.

enter image description here

  • Did you find a solution to this issue? I am trying to reduce the number of vertices in some large polygon layers without changing the shape of the polygons.
    – Mike
    Jul 3, 2020 at 23:39
  • @Mike there is an accepted answer by vagvaf below
    – Midavalo
    Jul 4, 2020 at 2:30

1 Answer 1


Vector -> Geomtry Tools -> Simplify Geometries. You have to experiment with the tolerance though...

Otherwise you can make a custom script that checks if the azimuth of two concecutive segments is the same and in that case to delete the middle vertex.

  • Yes, I tried Simplify geometries, but the problem is, that for other features I need other tolerance, so I want to automatized this process. I thought it could be some script or tool for doing this. So I will need create this one. Last question. What v.generalize? Is there any chance that particular algorithm could do this work? Algorithms in doc are not well-desribed
    – Bulva
    Jul 29, 2016 at 18:15

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