Symbolizing Isochrones in QGIS

Question

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

Answer 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.

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:

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

It will remove overlapping polygons located in one polygon layer.