Hi, Sorry for the bad math :)
I mixed up things. With 03-sec resolution, I have 1.4 billion cells, and r.watershed would need 45.5 GB. With 01-sec resolution, I have 12.8 billion cells and r.watershed need about 415 GB. The Location is in a drive with 1TB free. So this shouldn't be a problem. I'm running it now and it seems it's going to work. I'll report on this tomorrow. I think I didn't expressed correctly the r,terraflow issue. I didn't meant if the rows/columns limit is needed in the sense of it being a required parameter, but it was more of a general question, in the sense of 'do we need to have that limit hardcoded?' I can open a ticket on this issue. best Carlos On Tue, Jan 10, 2017 at 2:51 PM, Markus Neteler <[email protected]> wrote: > 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 > -- Prof. Carlos Henrique Grohmann Institute of Energy and Environment - Univ. of São Paulo, Brazil - Digital Terrain Analysis | GIS | Remote Sensing - http://carlosgrohmann.com http://orcid.org/0000-0001-5073-5572 ________________ Can’t stop the signal.
_______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
