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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

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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.

enter image description here

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:

enter image description here

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

enter image description here

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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