On Wed, May 2, 2018 at 2:21 PM, Markus Neteler <[email protected]> wrote: > On Wed, May 2, 2018 at 7:13 PM, Martin Landa <[email protected]> wrote: >> Hi, >> >> one of my colleague is dealing with flow accumulation calculation in >> GRASS, and comparing results with Esri ArcGIS (builtin Flow >> Accumulation [1]). Tool in ArcGIS to me knowledge uses D8, so we run >> r.watershed with -s flag and also -a flag to avoid negative values. >> Resultant values are very different. >> >> * Esri ArcGIS (range: 0 - 20741) >> * r.watershed -s (range: -34068 - 5697) >> * r.watershed -sa (1 - 34068) > > I'd suggest to look at the univariate statistics first (r.univar -e) > and compare that instead of min/max only.
Also, r.watershed uses least-cost path, unlike the arcmap tool. Did you fill the depressions before running the arcmap tool? Anna > > markusN > >> Do you have idea why results are so different? Thanks for any pointers >> in advance! Martin >> >> [1] >> http://desktop.arcgis.com/en/arcmap/10.5/tools/spatial-analyst-toolbox/flow-accumulation.htm >> >> -- >> Martin Landa >> http://geo.fsv.cvut.cz/gwiki/Landa >> http://gismentors.cz/mentors/landa >> _______________________________________________ >> grass-user mailing list >> [email protected] >> https://lists.osgeo.org/mailman/listinfo/grass-user > > > > -- > Markus Neteler, PhD > http://www.mundialis.de - free data with free software > http://grass.osgeo.org > http://courses.neteler.org/blog > _______________________________________________ > grass-user mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/grass-user _______________________________________________ grass-user mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/grass-user
