I'm using QGIS 2.12.0 and am trying to formulate a hierarchy for the risk factor associated with footpath polygons based on their proximity to pedestrian generators and the importance factor of that generator. For example, a bus stop will have a buffer radius of 100m and a factor of 10, while a small park will have a radius of 400m and a factor of 5. When the buffers are created, it's obviously going to create several hundred overlapping buffers and I wanted each intersecting segment to inherit a cumulative factor based on the overlapping factors (I've tried to illustrate what I mean in the pic). Heat maps using the factor work ok, but they don't take the radius into account.
Does anyone have any ideas how I might go about achieving this?