That's a good point Thayer. Will do. Will do On Tue, Jan 13, 2015 at 1:02 PM, Thayer Young <[email protected]> wrote:
> Daniel, > > Before you go through the trouble of recompiling you may want to try > downloading a smaller SRTM DEM from Earth Explorer and make sure it works > with r.terraflow. I would recommend making sure r.terraflow works at all > on your system. Then scale up to the full mosaic and see if you still have > a problem. > > -Thayer > > > ------------------------------ > *From:* Daniel Victoria <[email protected]> > *To:* Charlie Shobe <[email protected]> > *Cc:* Thayer Young <[email protected]>; "[email protected]" < > [email protected]> > *Sent:* Tuesday, January 13, 2015 9:17 AM > *Subject:* Re: [GRASS-user] r.terraflow on massive DEM > > 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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