Ouch! That means that probably, the person who imported the data, converted it to integer without knowing...
Anyway, I'll still need to recompile r.terraflow if I'm to use on such a large region (ncol=141114 x nrow=14048). Thanks Daniel On Tue, Jan 13, 2015 at 12:12 PM, Charlie Shobe <[email protected]> wrote: > Hi Daniel, > > I believe that SRTM data does in fact provide floating point elevation > values, so you may want to try working with the DEM as type FCELL from the > very beginning. I don't know if this will help solve your problem, but the > last time I brought in SRTM (1 arc second) data it was type FCELL and > contained several decimal places of precision. > > Good luck, > > Charlie > > > On Jan 13, 2015, at 4:00 AM, Daniel Victoria <[email protected]> > wrote: > > Stephan, I'll give r.watershed a try and let it run for a couple of days. > Thanks > > Thayer, I used r.recode because the person that sent me the data messed up > the null values. So in order to fix that I did: > 1) use r.external to bring the data to Grass > 2) fix null values with r.recode, which was faster than r.null > > But I gave up on that path and since imported the data (r.in.gdal) and > fixed the null values with r.null. > I'm also using integer values (CELL type) because from what I heard, SRTM > does not provide floating point data. > > Now I tried to run r.terraflow but I got a type error which asked me to > use r.terraflow.short. Since I don't have that command in my grass > instalatin, I converted the SRTM data to float. But that was to no avail > since it's now giving me a dimensions type overflow error and asking me to > change the dimension_type and recompile. > > I'll give r.watershed a try. If that does not work, I'll see if I can > recompile. > > Thanks > Daniel > > On Mon, Jan 12, 2015 at 9:22 PM, Thayer Young <[email protected]> wrote: > >> With regards to the size of DEM, if you can get the command to run it >> may take several days to finish, this is more than twice the size of the >> Washington State DEM that took the authors 33 hours in 2003 (Arge, Chase, >> Halpin, Toma, Urban, Vitter, Wickremesinghe Efficient Flow Computation on >> Massive Grid Terrain Datasets Geoinformatica Volume 7 Issue 4, December >> 2003 Pages 283 - 313 ). My mid-2014 computer runs at about twice the >> speed quoted in the paper. >> >> Did you r.recode it to make it smaller? In flat areas you need the data >> contained after the decimal point to allow the flow a chance to make it >> down hill, otherwise you can get streams going no where near where they do >> in real life. I have never tried running r.terraflow on an integer raster, >> I know that it works on decimal rasters. >> >> -Thayer >> >> >> >> ------------------------------ >> >> Date: Mon, 12 Jan 2015 09:59:40 -0200 >> From: Daniel Victoria <[email protected]> >> To: grass <[email protected]> >> Subject: [GRASS-user] r.terraflow on massive DEM >> Message-ID: >> <CA+irsJjf7xhWgU968D+4+xc2YGJ=_n4xjtp0_weu1zportt...@mail.gmail.com> >> Content-Type: text/plain; charset="utf-8" >> >> >> Hi list, >> >> I'm trying to run r.terraflow on a very large DEM but I wander if it's >> __too large__. >> >> The region dimensions are: >> ncol=141114 >> nrow=140487 >> Data type = CELL >> >> The map is actually a reclass map of a raster that I imported using >> r.external. >> >> When I run r.terraflow I get: >> >> r.terraflow elevation=srtm_brasil@PERMANENT filled=srtm_fill >> direction=flowdir swatershed=sink accumulation=flowacc tci=srtm_tci >> directory=E:\terraflow_temp >> >> WARNING: raster srtm_brasil is of type CELL_TYPE --you should use >> r.terraflow.short >> ERROR: [nrows=140487, ncols=141114] dimension_type overflow -- change >> dimension_type and recompile >> (Mon Jan 12 09:57:18 2015) Command finished (0 >> sec) >> >> However, I don't have an r.terraflow.short command >> I'm running Grass 7.0.0beta4 from OsGeo4W >> >> Cheers >> Daniel >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: < >> http://lists.osgeo.org/pipermail/grass-user/attachments/20150112/a27c139f/attachment-0001.html >> > >> >> ------------------------------ >> >> _______________________________________________ >> grass-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/grass-user >> >> End of grass-user Digest, Vol 105, Issue 16 >> ******************************************* >> >> >> >> _______________________________________________ >> grass-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/grass-user >> > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > >
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