Thanks Markus, the problem with the v.voronoi is that the polygon borders will be calculate based on point distance and not on the cost surface. Any other input? Best Giuseppe
On 19 January 2017 at 02:38, Markus Metz <markus.metz.gisw...@gmail.com> wrote: > > > On Wed, Jan 18, 2017 at 8:16 PM, Giuseppe Amatulli < > giuseppe.amatu...@gmail.com> wrote: > > > > Hi all, > > > > I would like to "segment" an image using a sort of Voronoi algorithm on > a cost surface instead of distance between point. > > > > Below you can see an image where the black pixels identity areas with > high cost value. I would like to identify the "valley" between theses black > areas. > > > > In the second image I draft by hand an ideal solution for few high cost > areas. > > > > Which grass command can do this kind of delineation? > > You can use v.voronoi: first extract the pixels with high cost values with > e.g. > r.mapcalc "high_cost = if(surface_map > threshold_value, 1, null())" > > Then convert to vector areas with > r.to.vect input=high_cost output=high_cost type=area > > Now create Voronoi triangles for areas with > v.voronoi input=high_cost output=high_cost_voronoi -a > > HTH, > > Markus M > > > > Thanks, > > > > Giuseppe > > > > > > > > > > > > > > -- > > Giuseppe Amatulli, Ph.D. > > > > Research scientist at > > Yale School of Forestry & Environmental Studies > > Yale Center for Research Computing > > Center for Science and Social Science Information > > New Haven, 06511 > > Teaching: http://spatial-ecology.org > > Work: https://environment.yale.edu/profile/giuseppe-amatulli/ > > > > > > > > > > _______________________________________________ > > grass-user mailing list > > grass-user@lists.osgeo.org > > https://lists.osgeo.org/mailman/listinfo/grass-user > > -- Giuseppe Amatulli, Ph.D. Research scientist at Yale School of Forestry & Environmental Studies Yale Center for Research Computing Center for Science and Social Science Information New Haven, 06511 Teaching: http://spatial-ecology.org Work: https://environment.yale.edu/profile/giuseppe-amatulli/
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