On Wed, Jan 14, 2015 at 11:48 AM, Daniel Victoria <[email protected]> wrote: > Hi Markus, > > I was using r.terraflow because I had converted my voids to negative values > while the areas outside the country where set to null. > But the data is proving to be too big and I'll just skip the gap-filling for > now. Might do it later on, filling the gaps in the import process. > > The SRTM v3 you pointed out is very good but it's the 3-arcsec resolution. > I'm working with the 1-arcsec res.
Then you could try the gap-filled 1 arc sec version of SRTM v3: https://lpdaac.usgs.gov/products/measures_products_table/srtmgl1 Markus M > > Cheers and thanks > Daniel > > On Tue, Jan 13, 2015 at 5:40 PM, Markus Metz <[email protected]> > wrote: >> >> On Tue, Jan 13, 2015 at 7:52 PM, Daniel Victoria >> <[email protected]> wrote: >> > >> > Now, the thing is, my main interest is to fill the voids in the SRTM >> > data. >> > So I though about using r.terraflow to get the filled elevation. Should >> > I >> > continue on that path or would it be better to use r.fill.null on a >> > large >> > dataset? >> >> r.terraflow does not fill voids, it fills sinks. Use SRTM v3 [0], this >> is gap-filled. Using r.fill.null on SRTM v2 will not give you the same >> quality. r.terraflow has a limit on the number of rows and columns >> (max 32,767 each). r.watershed also has a limit on the number of rows >> and columns, but that is max 2,147,483,647 each. In any case, you >> should use GRASS 7 for such large datasets. >> >> Markus M >> >> [0] https://lpdaac.usgs.gov/products/measures_products_table/srtmgl3 >> >> > >> > Thanks >> > Daniel >> > >> > On Tue, Jan 13, 2015 at 1:46 PM, Daniel Victoria >> > <[email protected]> >> > wrote: >> >> >> >> Charlie, >> >> >> >> I just downloaded some SRTM 1arc sec. from EarthExplorer. The data is >> >> supplied in 3 different file types, GeoTIFF, DTED or BIL and they are >> >> all in >> >> Integer values (Int16). No floating point elevation values. >> >> >> >> Cheers >> >> 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 >> >> >> >> >> > >> > >> > _______________________________________________ >> > 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
