QGIS: GRASS "V.net.iso" + Slope

Question

I wonder if someone knows a way to calculate time-cost isochrones in a bike road network layer, taking the slope into consideration.

The GRASS tool "v.net.iso" allows to create a line-vector layer with categories depending of how far the roads are from a determinated point. Having the data about the speed allowed me to do the analisys with time-cost categories.

But I would like the analisys to show how slope affects the isochrones: It doesn´t take the same time cycling towards the top of a hill than getting down. So taking the slope into consideration would make the analysis more attached to the reality.

Answer 1

You could use v.to.db to upload the respective slopes for the vector line segments from a slope map.

Probably you need to split the vector lines into short segments prior to v.to.db using v.split in order to get a realistic representation of the slopes.

Eventually run v.net.iso with cost taken from the slope column (just guessing, maybe the cost column needs some extra data treatment to better represent the cost).