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?