I ran an accessibility analysis on a road network with GRASS GIS (v.net.iso Tool) from different nodes in the network.

Using QGIS 2.18, I need to attach the resulting layer to the road network again. This is because v.net.iso puts out a layer containing just the distance categories. In my case 3 categories since I ran an analysis with 2 different distances (5km, 7,5km and above is cat 3).

Now if I use the "Join attribute by location" tool, I can choose the starting layer to which I want to join the attributes of the road network layer (street numbers, car counts etc.). In my case this would be the layer which GRASS put out.

The problem is, that with "Join attribute by location" a part of road B, which belongs to distance category 1 is attributed with features of road A because this is, where category 1 "started". I tried to show this in the picture below. I would need to "cut" the roads layers with its segments with the category layer but I dont't know how.

enter image description here

  • A quick workaround might be to create a relatively small negative buffer of the layer to be joined. Clip that same layer with the negative buffer and then perform the join. This will remove the geometry end overlap returning the attributes you want rather than the overlapping attributes. – user92055 Feb 28 '17 at 1:01

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