I'm working on a 15*10 km area, splatted in a 50*50 m cell grid. I want to compute the time needed to travel from a single starting point to each cell centroid, combining driving and walking time.

I placed a point every 30 m along my trail/roads. Using pgrouting,I already have the least time cost from my single startpoint to each of these points.

I computed the shortest path of each centroid to the nearest trail/road point. Assuming the same point-centroid walking speed (4 km/h), I get a time for each. I had first used the "Walking time" extension on those segments, but some times weren't realistic (canyons).

nearest nodes

But the time costs limits are raw on the raster: the nearest point on the road/trail isn't necessarily the fastest.

Roads/hiking trails and total time raster. As you can see, there are raw limits in time costs

Beside that, this approach doesn't take into account the slope, I tried r.walk and r.drain, but I can't figure out how to use it with all this : there are over 4 000 roads/trails nodes and 27 000 centroids !

How can I get the least-cost path from any of the centroid to the fastest trail/road point ?

I'm using Qgis and Grass.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.