On Tue, Jan 10, 2017 at 12:30 PM, Carlos Grohmann <[email protected]> wrote: > Hello all > > I'm working on deriving a nice drainage network for the Amazon basin. The > problem is that the area is too large. > > The region settings are these: > projection: 3 (Latitude-Longitude) > zone: 0 > datum: wgs84 > ellipsoid: wgs84 > north: 6:17N > south: 21:30S > west: 80:37W > east: 44:50W > nsres: 0:00:03 > ewres: 0:00:03 > rows: 33340 > cols: 42940 > cells: 1431619600 > > With 14.3 billion cels,
Isn't it 1431619600 = 1.431.619.600 = 1.4 billion cells? > r.watershed would need about 450 GiB of disk space > running in seg mode, is that correct? (from the manual, 31 MB for 1 million > cells). https://grass.osgeo.org/grass72/manuals/r.watershed.html#large-regions-with-many-cells " The upper limit of the ram version is 2 billion (2^31 - 1) cells, whereas the upper limit for the seg version is 9 billion-billion (2^63 - 1 = 9.223372e+18) cells." So that would be supported by r.watershed. > I do have that disk space available, but it's in a secondary drive. If I set > TMPDIR to that drive, will r/watershed use it? I ask because the > documentation (https://grass.osgeo.org/grass72/manuals/variables.html) only > says that this environmental variable is used by "[Various GRASS GIS > commands and wxGUI]". AFAIK the TMPDIR variable is not relevant here. The tmp dir is location/mapset/.tmp/ which you could link to the extra drive. This should be simplified for sure: Involved code: https://trac.osgeo.org/grass/browser/grass/trunk/lib/gis/file_name.c https://trac.osgeo.org/grass/browser/grass/trunk/lib/gis/tempfile.c Please open a ticket with the relevant info in it. > On a side note, r.terraflow should be an alternative for such a large > dataset, but from the manual: > "r.terraflow has a limit on the number of rows and columns (max 32,767 > each)". > That's the size of a positive short integer. Is this limit still needed? I have no idea here, did you try it? Markus -- Markus Neteler http://www.mundialis.de - free data with free software http://grass.osgeo.org http://courses.neteler.org/blog _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
