First of all I use QGIS. I got a bunch of polygons that describe a 10 min. footway from different addresses.

What I want to do now is to illustrate the areas where the polygons are overlapping. My trouble is how to show the differences between 2 overlapping polygons and 3, 4 or 5 overlapping ones.

My idea is to do some query where I get a Layer with all those overlaps and in one column of the attribute table it says how many polygons are overlapping. I hope the attachment helps to understand what I'm looking for.


Do you have any idea how to do that?

  • If I understand you correctly, a simple "Intersection" tool (in the Processing Toolbox) is what you need. It can be done even if the polygons are the same layer – 15Step Feb 15 '18 at 10:12
  • 1
    Could this be a possibility? – Kazuhito Feb 15 '18 at 12:34
  • Thanks a lot, Kazuhito! That's excactly what I was looking for. – blackyellow Feb 19 '18 at 9:45

With respect to styling / display, you don't even need to compute the number of intersecting polygons. Open the layer style and set the feature blending mode to addition (while in there, you may want to test other modes)

Feature blending mode - addition

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