Re: [GRASS-user] r.mapcalc questions
Frank Broniewski wrote: > I have some questions concerning the use of r.mapcalc. I have a DEM made > by r.surf.contour using the approach in the wiki (multiplying by > 10)[1]. Now when calculating back the original values I wonder about > the values given by r.info. Calculation is done like so within the > wxpython map calculator: r.mapcalc dtm_surf = dtm_surf.100k / 10.0 > > Now r.info tells me: > Data Type:DCELL > which seems OK, but > Range of data:min = 130 max = 555 > -> shouldn't these be float values after calculation? > and the comments > dtm_surf.100k / 10 > I definitely typed 10.0! Where're my .0s? For DCELL, r.info uses %.15g for the range, while r.mapcalc uses %.8g for floating-point constants in the history. The "%g" format specifier omits trailing zeros, and omits the decimal point if nothing follows it. The alternatives are "%f", which uses a fixed number of decimal places, "%e" which always uses scientific (exponential) notation, or "%#g", which always includes the decimal point and trailing zeros. All of these have their drawbacks. Would would be nice would be like the existing behaviour but always retaining the decimal point and at least one digit, but there isn't any easy way to get that. > A quick visual > verification with r.slope.aspect shows some terracing effects. That lets > me suspect that the conversion to a DEM float raster failed somehow - > but why? Note that r.surf.contour works in floating-point and generates DCELL output, so the multiplication and subsequent division should be unnecessary. -- Glynn Clements ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Grass-Windows - Error using tcltk's messages
On Tue, Jun 7, 2011 at 5:35 PM, Luisa Peña wrote: > Greetings > I have compiled GRASS6.4 with Osgeo4w and it worked just fine. Then I > decided to create an installer and it worked just fine but... tcltks > translation is not working. I only need the v.digit . And it's not working > for any language. Any tips on what might be happening? The messages were not tagged for translation in GRASS 6.4. I have backported that now, still have to update the .po files (asap). Markus ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] r.mapcalc questions
Hi, I have some questions concerning the use of r.mapcalc. I have a DEM made by r.surf.contour using the approach in the wiki (multiplying by 10)[1]. Now when calculating back the original values I wonder about the values given by r.info. Calculation is done like so within the wxpython map calculator: r.mapcalc dtm_surf = dtm_surf.100k / 10.0 Now r.info tells me: Data Type:DCELL which seems OK, but Range of data:min = 130 max = 555 -> shouldn't these be float values after calculation? and the comments dtm_surf.100k / 10 I definitely typed 10.0! Where're my .0s? A quick visual verification with r.slope.aspect shows some terracing effects. That lets me suspect that the conversion to a DEM float raster failed somehow - but why? I'm using the osgeo4w build on windows 7 64. GRASS GIS version is 6.4.1 (2011). Many thanks Frank [1] http://grass.osgeo.org/wiki/Contour_lines_to_DEM -- Frank BRONIEWSKI METRICO s.à r.l. géomètres technologies d'information géographique rue des Romains 36 L-5433 NIEDERDONVEN tél.: +352 26 74 94 - 28 fax.: +352 26 74 94 99 http://www.metrico.lu ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Reference for Boyles algorithm in v.generalize
Hello, i posted that question already some time ago but didn't get any reply/idea... Here again: I am looking for the literature reference for Boyle's algorithm in v.generalize. What is the source this tool is based on. Does anyone know the original literature? Thank you /Johannes -- NEU: FreePhone - kostenlos mobil telefonieren! Jetzt informieren: http://www.gmx.net/de/go/freephone ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Movement Cost: Euclidean results?
Dear GRASS-users, I want to obtain a movement cost layer (r.walk) which only regards pure walking cost (without a friction layer). I've generated a 32 bit geotiff DEM (not too big) and a constant value = 1 grid as friction surface (for being neutral). Unfortunately GRASS only gives me a symmetrical result as there would be no relief. Is is not possible to perform a simple movement-cost analysis without any optional friction maps? Using a constant value grid (or lamda = 0) doesn't work unfortunately. I'm always getting symmetrical/euclidean results. Thank you! Regards David ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: Writing a script for image classification
you can save the script as myscript.sh, and start Grass in a terminal (type grass) and select your location and mapset (now you can close the gui). In the terminal you go to the directory where you saved the script, make it executable (type chmod 0755 myscript.sh) and start the script with ./myscript.sh.. before that you need to modify the script, i.e. set the variablesfor example maps="yourmapset" is your mapset, raster"band1,band2,band3" are your raster files you want to group..if you already made a signaturfile, you can skip most of the script - Department of Geography and Regional Research UZA II, Althanstr. 14 1090 Wien, AUSTRIA http://geooekologie.univie.ac.at -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Writing-a-script-for-image-classification-tp6448874p6453188.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: Writing a script for image classification
I use Linux, Ubuntu 11.04. -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Writing-a-script-for-image-classification-tp6448874p6453003.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] v.surf.rst vs r.slope.aspect
Thanks Edgar, the results are indeed better with a bit of smoothing. Cheers, Pierre 2011/6/7 Edgar Pimiento : > Pierre, > > -r.param.scale is more appropriate for high resolution elevation data than > other modules. It permits to select the kernel (window size) for the > estimation of parameters. Land surface parameters depend on DEM resolution > and size of computation window. High elevation data are susceptible to noise > and it is better to use a kernel larger than 3 when calculating slope and > other parameters. > > For references check module help and the following: Wood, J.D. (1996) The > geomorphological characterisation of digital elevation models PhD Thesis, > University of Leicester, UK,http://www.soi.city.ac.uk/~jwo/phd; Hengl, T. and > I. S. Evans (2009). Mathematical and Digital Models of the Land Surface. > Geomorphometry- Concepts, Software, Applications. T. H. a. H. I. Reuter, > Elsevier. Volume 33: 31-63; and Reuter, H. I., T. Hengl, et al. (2009). > Preparation of DEMs for Geomorphometric Analysis. Geomorphometry- Concepts, > Software, Applications. T. H. a. H. I. Reuter, Elsevier. Volume 33: 87-120. > > > Edgar Pimiento > e_pimie...@yahoo.com > Public Works Division, Shimane Prefecture, Japan > > > From: Pierre Roudier > To: GRASS > Sent: Tuesday, June 7, 2011 2:23 PM > Subject: [GRASS-user] v.surf.rst vs r.slope.aspect > > Dear list, > > For a project, I need to derive parameters like slope and aspect from > a high-res DEM from a LiDAR point cloud. > > There are several way to do this in GRASS: > > - v.surf.rst > - r.slope.aspect > - r.param.scale is a bit special and, I think, has a different purpose. > > How do RST and r.slope.aspect compare? I can see (using difference > maps or the profile tool) the results are different, but I'm not too > sure which one to use at the end of the day. > > Any thoughts/references on that? > > Cheers, > > Pierre > > -- > Scientist > Landcare Research, New Zealand > ___ > grass-user mailing list > grass-user@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Scientist Landcare Research, New Zealand ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Grass-Windows - Error using tcltk's messages
Hi I have exacly the same problem. Is this some limitation on building these installers? Or it may be some error that both of us did Antonio __ Information from ESET NOD32 Antivirus, version of virus signature database 6188 (20110607) __ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: Writing a script for image classification
Hi, are you using Windows or Linux? - Department of Geography and Regional Research UZA II, Althanstr. 14 1090 Wien, AUSTRIA http://geooekologie.univie.ac.at -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Writing-a-script-for-image-classification-tp6448874p6452758.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
