[GRASS-user] Questions concerning r.mapcalc, r.cost and high resolution DEMs

Hello, i just joined this mailing list and i hope i'm doing everything right. I'm in a project where i try to provide an easy way to do a cost-distance analysis, based on a given raster DEM, i did this with ArcGIS earlier but i want more people to be able to use this simple (and faster) approach,

Re: [GRASS-user] Questions concerning r.mapcalc, r.cost and high resolution DEMs

Daniel For the first problem I would sugest you to filter high slope values r.mapcalc h_m=if(slope<70, (0.00016*(exp(3.5*(abs(tan( "slope_in_degree" )+0.05)*cellsize, null()) For the second problem, did you try to use a smaller percentage (say 10%)? best regards El 24/03/14 10:15, D

Re: [GRASS-user] Questions concerning r.mapcalc, r.cost and high resolution DEMs

Hi Daniel, concerning your first point, you could try to run simpler calculations of your quite nested mapcalc expression, in order to pin down which cells cause problems at certain levels of calculations. Eg. just run a simpler mapcalculation like and identify the levels of calculation and cells

[GRASS-user] projection issue

Hello, the trouble I am currently experiencing is dealing partly with cs2cs, but partly with grass, so I post my question on this list... Being within a Mercator location, defined with the location wizard (calling epsg:3857), I type : echo "6.46311951 45.78037144" | m.proj -idg

Re: [GRASS-user] projection issue

Comment on my previous message : if we have a closer look at parameters, we notice a difference between the current (grass location) projection parameters and epsg:3857 parameters : Current : a (semi-major axis) = 6378137 rf (flattening factor inverse) =298.257223563 am I wrong or

Re: [GRASS-user] projection issue

On 24/03/14 13:10, Vincent Bain wrote: Comment on my previous message : if we have a closer look at parameters, we notice a difference between the current (grass location) projection parameters and epsg:3857 parameters : Current : a (semi-major axis) = 6378137 rf (flattening f

Re: [GRASS-user] projection issue

Le lundi 24 mars 2014 à 13:49 +0100, Moritz Lennert a écrit : > You're not wrong. The difference comes from the GRASS file > /etc/ogr_csv/pcs.csv in which there is a specific rule set for 3857. > > Don't know why, though. > > Moritz Thank you Moritz for your reply. Yes, I finally tried to make

Re: [GRASS-user] projection issue

On 24/03/14 14:03, Vincent Bain wrote: Le lundi 24 mars 2014 à 13:49 +0100, Moritz Lennert a écrit : You're not wrong. The difference comes from the GRASS file /etc/ogr_csv/pcs.csv in which there is a specific rule set for 3857. Don't know why, though. Moritz Thank you Moritz for your reply

Re: [GRASS-user] projection issue

Le lundi 24 mars 2014 à 15:00 +0100, Moritz Lennert a écrit : > I guess https://trac.osgeo.org/gdal/ticket/3962 is related to this. interesting discussions confusion/debate on this particular point is weird : there should be only one way to choose between a sphere and an ellipsoid ? As far as

Re: [GRASS-user] Elevation differences between endpoints of least cost paths

Thank you! -Don -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 From: jctorres mailto:jctor...@ugr.es>> Date: Saturday, March 22, 2014 12:04 AM To: "MacQueen, Don" mailto:macque...@llnl.gov>>, "grass-user@lists.osgeo.org

Re: [GRASS-user] visited lines

On 20/03/14 11:41, Annalisa Minelli wrote: Hi list, I have a maybe stupid question, but I should identify (by category) the net lines visited from going to one point to another along a net. I tried the v.net module, but I'm not colpletely sure to have understood what the 'nreport'

Re: [GRASS-user] visited lines

On 24/03/14 17:10, Moritz Lennert wrote: On 20/03/14 11:41, Annalisa Minelli wrote: Hi list, I have a maybe stupid question, but I should identify (by category) the net lines visited from going to one point to another along a net. I tried the v.net module, but I'm not colpletely s

Re: [GRASS-user] visited lines

Hello Moritz, I tried your solution and since I generated the path using the same v.net.path with the same -s flag (which preserves the segments) that you suggest, when I do the v.distance trying to "copy" the attribute cat from the net segments it seems not to work properly - I mean, it copies "so

Re: [GRASS-user] projection issue

Vincent: > the trouble I am currently experiencing is dealing partly with > cs2cs, but partly with grass, so I post my question on this > list... > > Being within a Mercator location, defined with the location > wizard (calling epsg:3857), I type : ... > I can't figure what is going wrong. Would

Re: [GRASS-user] projection issue

Le lundi 24 mars 2014 à 13:24 -0700, Hamish a écrit : > > Hi, > > First of all, avoid using Google's "spherical mercator" projection for > anything other than necessary data import/export if you can possibly help it. > But sometimes we don't have a choice, so.. > I wish I could never have hea

[GRASS-user] reading/converting Z-map format with Grass/Gdal

Dear list, I have a Z-map format text file, representing a geological horizon. I need to convert it to some other format, something like a simple XYZ or XYT text file. Example of format is below. Any suggestions if I can achieve this with Grass/Gdal? regards, Szilard ! ! ZIMS FILE NAME :