Thanks for your answer, I missunderstood the meaning of r.thin. But how can I get rather compact and smooth polygons representing watersheds without any slivers or attached/appended fractals of the size of one raster cell? Is it possible to solve such a problem with v.clean or something like a "raster smoothing" with r.neighbour?
Christian > -----Original Message----- > From: Maciej Sieczka [mailto:[EMAIL PROTECTED] > Sent: Tuesday, August 21, 2007 9:21 PM > To: Christian Braun > Cc: 'Hamish'; [email protected] > Subject: Re: AW: [GRASS-user] Problems with r.terraflow and r.thin > > Christian Braun wrote: > > Hi, > > > > ok I had to learn that you can't compare the results of r.terraflow > > and r.watershed regarding the watershed generation. I think > > r.watershed gives me the better results, so I will try to > use this module. > > But I still have the problem with r.thin to get rid of the linear > > features describing watersheds. The pics I had attached are, of > > course, the results of thining my watersheds of > r.terraflow. First pic > > result watersheds of r.terraflow, second pic the thining result. > > Christian > > Forgive me if I got you wrong, but are you by any chance > running r.thin on a raster map made of adjacent watershed > polygons? Please note that r.thin is supposed to be used for > thinning raster *line* features. The manual reads: "Thins > non-zero cells that denote linear features in a raster map layer". > > If you need watershed borders as raster lines, you can use > r.to.vect to extract watersheds as vector polygons (areas) > and rasterise their boundaries with v.to.rast type=line (if > this doesn't work, convert boundaries into lines first with > v.type, and run v.to.rast type=line on this). > > Maciek > _______________________________________________ grassuser mailing list [email protected] http://grass.itc.it/mailman/listinfo/grassuser
