#2036: Failed watershed analysis on Grass --------------------------+------------------------------------------------- Reporter: mehmeto | Owner: grass-dev@… Type: defect | Status: closed Priority: normal | Milestone: 6.4.4 Component: Raster | Version: 6.4.2 Resolution: fixed | Keywords: LFS, r.watershed Platform: MSWindows 7 | Cpu: x86-64 --------------------------+-------------------------------------------------
Comment(by mehmeto): Replying to [comment:7 hamish]: > this isn't really that large of a region, you usually hit 2 GB files at ~ 45000x45000 rows x cols. this is much smaller, > > If you calculate 4 * 60175190 bytes = 240700760 which is > 2^31. > > missed a 0, actually it's 9 times smaller than 2^31. It only wants to allocate 241mb RAM, so probably not a large-file problem. How much do memory does your computer have? It has 8GB. Also thank you for updating the tutorial. Now I can do watershed analysis at least on a demo map but my real data will be larger. I will need to work on an area of about 5,000 square km. and the map scale will be about 1:25,000 or even lower. I will also need to transform contours to DEM before start using r.watershed. Since I will work on a PC, memory problems seem inevitable. I know one suggested method to overcome memory limitations is dividing a large map to smaller pieces but in a wathershed analysis that will mean false or missing results. Or, maybe I will need to divide the map into overlapping sections to make sure no basins are missed and then manually stitch the sections, which sounds to me a very laborous procedure now. Do you have any ideas how to do that, or any forums where I can ask? -- Ticket URL: <http://trac.osgeo.org/grass/ticket/2036#comment:13> GRASS GIS <http://grass.osgeo.org> _______________________________________________ grass-dev mailing list grass-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-dev