Kwas wrote: > > > Hello, > I have a raster map (dem) and I want to select a region of the raster > corresponding to a polygon that is in a vector map. What is the best > way to do this? It looks like r.in.poly might be along the lines of > what I need but in that case I think I would need to generate the ascii > poly file first but I'm wondering if there is a better way? Seems > like > there should be a single command to do this. > > My vector map has 45 polygons with cat values 1..45, so I would like > to get a section from my raster map corresponding to one of the > polygons specified by cat value. > > appreciate any help! > thanks, > ken > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > >
Hello Ken, I am also new to GRASS, but I have been doing what you want quite a lot these days. There is probably a better way to do that (and I would like to "hear" it very much, specially if there is a single command to do this), but for now, I think the code below does the job: g.region vect=your_vector v.extract input=your_vector output=selected_polygon type=area where="cat=desired_cat" v.to.rast input=selected_polygon output=polygon_rasterized use=val type=area r.mask input=polygon_rasterized Now, any processing that you do will be applied only in the region corresponding to the selected polygon. If you want to create a raster corresponding to the selected polygon, just do: r.mapcalc "new_raster=any_old_raster" To take out the mask, just type: r.mask -r Hope this helps, Marcello. -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/how-to-get-raster-region-corresponding-to-vector-polygon-region-tp5192862p5193386.html Sent from the Grass - Users mailing list archive at Nabble.com. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
