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Is there any GIS function which gives back the polygons of the intersections by storing the number of the overlapping surfaces to an attribute?

Or do you have a script for this purpose?

A sample pic with transparency:

enter image description here

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  • Do you want the geometry of the intersections or are you talking about recording a reference to intersecting polygons such as [ID=1,ID=4,ID=5],[ID=4,ID=9] etc....
    – Liam G
    Commented Oct 12, 2016 at 21:22
  • I would like some layers with different levels of intersections. Or I prefer one layer where the intersecting features have the level of intersection in a field.
    – pnz1337
    Commented Oct 12, 2016 at 21:50
  • Are you trying to achieve something similar to what's explained in this ESRI blog ?
    – SaultDon
    Commented Oct 14, 2016 at 1:33
  • Interesting, thanks for the link. Actually I started to write a PyQGIS code, because I prefer open-source solutions.
    – pnz1337
    Commented Oct 14, 2016 at 13:22
  • I know, but are you trying to process your data to reach the same result?
    – SaultDon
    Commented Oct 14, 2016 at 22:53

1 Answer 1

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I used the following workflow to obtain results similar to what you seem to be looking for:

  1. Run the Intersection tool and select the same layer for the Input and Intersect layer.

  2. Run the Delete duplicate geometries tool as the output from Step 1 will produce annoying duplicates.

  3. Run the Join attributes by location tool and select the output layer from Step 2 as both input layers:

    Join attributes by location

    This step creates a count field which will contain the number of intersections for each polygon. However, if no polygon is being intersected, it will count as 1 so we need to subtract this in the next step.

  4. Run the Field Calculator and update the count field using the expression:

    "count" - 1
    

I used the workflow and seem to get reasonably correct results:

Example 1:

Count of 2

Example 2:

Count of 5


If you don't wan to do the above steps manually, you could create a model such as this one:

Model

Or you can download it and copy it to your /.qgis2/processing/models folder).

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    Thanks for your efforts Joseph, but I cannot accept it, since it gives only a similar result, that I want. I have to highlight those areas which are only covered by one polygon, covered by two polygon, and so forth.
    – pnz1337
    Commented Oct 13, 2016 at 12:25
  • 3
    @pnz - No problem at all, will keep it posted in case it might help others :)
    – Joseph
    Commented Oct 13, 2016 at 12:26

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