I have generated isochrones for London based on my parameters.

However, the isochrones by definition are overlapping polygons.

I would like to show the different polygons of the isochrones using different colors.

I have tried using gradient symbology, but the desired effect is not there since the overlapping polygons are making the different colors interact with each other.

I can separate the polygons into different files and then subtract each polygon from the others so that they don't overlap.

However, since I am relatively new to QGIS, I am wondering whether there is an alternate simpler way to achieve this visual effect?

I am using QGIS 3.4.1


You can use Union tool to get rid of the overlapping polygons and then add the colors you want to each polygon. Union tool is located under Vector -> Geoprocessing tools -> Union.

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But if the overlapping polygons are located in one layer, then it is better to use v.clean tool under Processing toolbox -> GRASS GIS 7 commands -> Vector -> v.clean, and under Cleaning tool use Break, as you can see below:

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In QGIS 3.4.1 it is under GRASS -> Vector -> v.clean and break is located under the cleaning tool:

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It will remove overlapping polygons located in one polygon layer.

  • I am using QGIS v3.4.1 and I cannot see the parameter called 'Cleaning tool' inside the v.clean interface
    – DotPi
    Nov 13 '18 at 6:37
  • @DotPi I updated the answer considering QGIS 3.4.1. It is better to mention QGIS version in your question.
    – ahmadhanb
    Nov 13 '18 at 6:53
  • Updated Question. It works now.
    – DotPi
    Nov 13 '18 at 7:12

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