On Fri, Jan 6, 2012 at 9:42 AM, Moritz Lennert <mlenn...@club.worldonline.be> wrote: > On 06/01/12 09:23, Markus Metz wrote: >> >> On Thu, Jan 5, 2012 at 12:12 PM, Massimiliano Cannata >> <massimiliano.cann...@supsi.ch> wrote: >>> >>> Moreover, >>> check that your dem has sinks filled (r.fill.dir) >> >> >> Since the drainage map has been created by r.watershed, sink filling >> is not only not needed but does more harm than good and should not be >> used to prepare a DEM for r.watershed. > > > for r.water.outlet I suppose... > > Could you explain why ?
Because r.water.outlet generates a watershed basin from a drainage direction map from r.watershed (says the manual), more generally, r.water.outlet uses as input map only a drainage map and not a DEM, thus it does not matter where the drainage map comes from, it could in theory also be properly encoded moving directions from a cost surface analysis. As pointed out by Micha and you, care must be taken with the coordinates, otherwise an unexpectedly small basin will be delineated. Additionally, r.water.outlet will most probably not work properly if the current region does not match exactly the drainage map. r.watershed has been designed from the very beginning by Chuck Ehlschlaeger in 1989 to work with raw DEMs and to produce realistic output without sink filling (see references in the manual). Markus M _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user