Hi Ivan and Helena, 149,040,000 Cells for the srtm 90m of Mekong river. computer is on 8Gb RAM. About 65 % done after 43.x hours, r.watershed basically does it, it seems. Of course efficiency is a problem here, but it does it.
yes r.terraflow goes to /tmp, that is considered a bug to me, not an enhancement... The location from which we have the GRASS dataset is generally the best guess for large empty Disk space. Cheers, Yann On 19/03/2008, ivan marchesini <[EMAIL PROTECTED]> wrote: > Dear Helena, > Thank you very much for your answer... > my problems are: > > * is the flowdirection output produced by r.terraflow suitable for basin > creation (like I can do with the drainage map created by r.watershed and > given as input to r.water.outlet)? Because this is my final target... > It seems to me that r.terraflow outputs aren't useful for basin > delineation... or I'm wrong? > > * I'm really interested in testing TerraSTREAM but, probably due to my > fault, I wasn't able to obtain a login and password... > > many many thanks > > Ivan > > > > > > > > Il giorno mar, 18/03/2008 alle 09.33 -0400, Helena Mitasova ha scritto: > > > Ivan - you may talk to Yann on this list before you buy more memory - > > he is trying to do the same as you , but with a bigger DEM and 8GB of > > memory (Yann I hope it is OK with you that I am revealing this here). > > My experience with large DEMs (up to 10,000x10,000) has been that I > > had to split the area into sections that were about > > 2000x2000 on 1GB memory computer) to get it done (I was able to do > > that for Panama because of its shape - many small watersheds rather > > than a single big one) - it took me several days to do that. > > Then I ran r.terraflow and I got it in 3 hours. > > > > Yann says that r.terraflow did not work for him - now I remember what > > the problem was when I tried to run it recently - > > it needs a LOT of hard drive space which is not a problem these days, > > BUT the default has been changed > > to /tmp which for my linux box is only 2GB or so. But when running > > r.terraflow you can define where > > you want the temporary files to be written - so give it something > > with a lot of space (tens of gigabytes at least) > > and it should run. I think that the default should be changed to > > where it was - I think it is the regular grass tmp where people > > usually have a lot of space for the data. > > > > If even that does not work you can give a try to brand new > > TerraSTREAM - see the link below > > (and let me know whether it works for you), > > > > Helena > > > > TerraSTREAM provides a series of components that > > perform flow modeling and terrain analysis tasks on very large digital > > elevation models and works equally well on TIN and grid DEMs. The > > algorithms > > used in the libraries have provable efficient performance in the > > worst case, > > even on very large terrains that do not fit in the main memory of the > > computer. > > TerraSTREAM 0.2 comes with direct GRASS and ArcGIS support as well as > > a simple > > standalone graphical user interface and powerful command line tools > > that can be > > used alone or integrated into most GIS environments by scripting. For > > more > > information about this release and for contact information, visit > > http://madalgo.au.dk/Trac-TerraSTREAM/. > > The TerraSTREAM 0.2 users guide is available here: > > http://madalgo.au.dk/Trac-TerraSTREAM/wiki/UsersGuide . > > > > > > > > On Mar 18, 2008, at 5:32 AM, ivan marchesini wrote: > > > > > Dear Grass Users and Developers, sorry for cross posting but we > > > hope the > > > argument can be of interest for all and we hope someone can give us a > > > solution to this problem.. > > > > > > We have this kind of problem: > > > * a large DEM (150000000 cells) > > > * an ordinary computer (2 GB ram) > > > * we must obtain the drainage map using r.watershed (without changing > > > resolution), because then we need to be able to calculate the upstream > > > basin for each cell (r.water.outlet). > > > * we have tried r.watershed straigth (but after few seconds a memory > > > allocation problem crashed the program) > > > * we have tried the "-m" option but after 4 days of work it is > > > still at > > > 0%. > > > * giving up the last option, because it takes too long, we have > > > monitored the ram usage by means of "free -m" and we have seen that > > > r.watershed rapidly saturate the ram and then, after a little usage of > > > swap (20 mb) crashes.. so it seems that r.watershed doesn't use swap > > > memory... (and is then unuseful, as we did, to increase the swap > > > memory) > > > * we have tried to modify > > > "Swappiness" (http://www.gentoo.it/doc/memory.html#doc_chap5) but > > > without success... the error is still the same > > > > > > > > > so at this point: > > > * is adding ram to the computer the only solution? > > > * if yes, how can we estimate the ram to buy! > > > * can we obtain some better results compiling grass with option > > > --enable-largefile > > > * does someone solved a similar problem in some other way? > > > > > > Thank you for your suggestions!!! > > > we hope really in your help > > > > > > Luca & Ivan > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > Ti prego di cercare di non inviarmi files .dwg, .doc, .xls, .ppt. > > > Preferisco formati liberi. > > > Please try to avoid to send me .dwg, .doc, .xls, .ppt files. > > > I prefer free formats. > > > http://it.wikipedia.org/wiki/Formato_aperto > > > http://en.wikipedia.org/wiki/Open_format > > > > > > Ivan Marchesini > > > Department of Civil and Environmental Engineering > > > University of Perugia > > > Via G. Duranti 93/a > > > 06125 > > > Perugia (Italy) > > > Socio fondatore GFOSS "Geospatial Free and Open Source Software" > > > http://www.gfoss.it > > > e-mail: [EMAIL PROTECTED] > > > [EMAIL PROTECTED] > > > tel: +39(0)755853760 > > > fax (university): +39(0)755853756 > > > fax (home): +39(0)5782830887 > > > jabber: [EMAIL PROTECTED] > > > > > > _______________________________________________ > > > grass-dev mailing list > > > [email protected] > > > http://lists.osgeo.org/mailman/listinfo/grass-dev > > > > > -- > Ti prego di cercare di non inviarmi files .dwg, .doc, .xls, .ppt. > Preferisco formati liberi. > Please try to avoid to send me .dwg, .doc, .xls, .ppt files. > I prefer free formats. > http://it.wikipedia.org/wiki/Formato_aperto > http://en.wikipedia.org/wiki/Open_format > > Ivan Marchesini > Department of Civil and Environmental Engineering > University of Perugia > Via G. Duranti 93/a > 06125 > Perugia (Italy) > Socio fondatore GFOSS "Geospatial Free and Open Source Software" > http://www.gfoss.it > e-mail: [EMAIL PROTECTED] > [EMAIL PROTECTED] > tel: +39(0)755853760 > fax (university): +39(0)755853756 > fax (home): +39(0)5782830887 > jabber: [EMAIL PROTECTED] > > _______________________________________________ > grass-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-dev > _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
