Hi Anna, Thank you for pointing that out. It always computes one way between two points indeed, but there is something that I should bring to light.
While I was initially computing least-cost paths with r.drain using r.walk outputs as inputs I noticed a possible problem. I ran two parallel tests with the same two points. In the first one, A was the starting position, while B the stop position. In the second one, B was the start point and A the stop point. In r.walk, the results were anisotropic indeed, both the walking cost and the movement direction raster outputs turned out different, as it would have been expected. But the r.drain module sadly did not generate different least-cost paths, despite using different inputs. I have also checked this more than once, just to be sure of it. At one point I have also come across an article (Gietl et al. 2008 - link below) where the authors discuss and compare l.c.p. results obtained with different GIS (including GRASS), and they had also experienced some problem with the module (page 4), but I am not sure if it's the same I'm having. In any case, if nothing can be done about it, then I will mention the limitation in the documentation. All the best, Nagy Edmond article - http://proceedings.caaconference.org/paper/106_gietl_et_al_caa2007/ -- Sent from: http://osgeo-org.1560.x6.nabble.com/GRASS-PSC-f4051248.html _______________________________________________ grass-psc mailing list grass-psc@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-psc
