GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) capable of handling raster, topological vector, image processing, and graphic data.

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How to increase the resolution of a 3D image in QGIS GRASS NVIZ

I'm trying to display 3D data in NVIZ within QGIS, but the result appears very low resolution in comparison to the same data in ArcScene. Any ideas as to how to improve the quality would be greatly ...
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18 views

Converting Landsat8 DN to TOA reflectance for use in envi

I am used to working in envi, however my current version does not support Landsat8. I downloaded GRASS for the express purpose of converting Landsat8 DN to TOA reflectance for use/analysis in envi. ...
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15 views

QGIS DEM Output cell size does not match DEM input cell size

As my first post I offer a humble apology if this is such a basic question as to make any of you cringe. I feel like I have exhausted my search skills and read through the QGIS documentation ...
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14 views

r.stream.* commands do not work in qgis environment

I have been working for a while with some grass commands in QGIS environment (r.watershed, r.terraflow, r.thin, r.to.vect etc) with out any problem. I haven't been able to get any results at all from ...
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9 views

GRASS GIS for geological mapping [closed]

Has anyone used GRASS GIS for geological mapping? I am trying to perform multispectral processing on open source GIS platform as I don't have access to ENVI software. Does anyone know a way to do ...
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36 views

Loading GRASS gives error installing QGIS Chugiak on Windows 8.1?

I am experiencing a problem installing QGIS 2.4 Chugiak on Windows 8.1, resulting in a error loading Grass. This may be a problem only affecting certain installations, I'm not sure. I am a noob on ...
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17 views

Trouble with r.out.gdal in GRASS GIS

I'm processing some landsat 8 files. I'm using this scene LC82260982013325LGN00 and I have to apply i.landsat.toar and export the result as a GTiff. However when I use r.out.gdal it takes a very long ...
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10 views

GRASS: v.drape, v.split and v.to.db on spearfish sample data

I am new to GRASS and started training on the spearfish sample data set in GRASS 6.4.3. I selected a bicycle tour and transformed it into a polyline. My next goal is to read out the slope and ...
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34 views

What's the difference between Processing GRASS and the GRASS toolbar?

Preparing a QGIS-course for my colleagues I stumbled over the following question: What is the difference between the GRASS commands in the processing toolbar and the GRASS Tools, that you access via ...
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84 views

LiDAR data density, returns per square meter

How can I compute a raster showing the number of return points per square meter using SAGA GIS or other open source software? My goal is to obtain a mask which would show me the places (cells) ...
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Problem with Command Console (GRASS GIS 7.0,0 beta2 on Windows 8.1)

I have a problem with Command Console. When I do for example, File-> Map display-> Add raster-> elevation, it works. But when I write into Command Console d.rast map=elevation@PERMANENT, it ...
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17 views

Execute Spyder within Grass GIS

I'm using GRASS Gis with a small Python script. Is there a way (for windows users) to use the sypder ide within grass? I looked at http://grasswiki.osgeo.org/wiki/Tools_for_Python_programming but ...
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15 views

Is my code for changing the resolution correct?

I have a raster files of daily minimum temperature (tmin) for the period 1962-2011 at a resolution of 1.125. I need to convert each single day raster file into 0.5 using inverse distance ...
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21 views

GRASS and r.viewshed

I'm trying to run the r.viewshed command using co-ordinates held in a .csv file I imported using v.in.ascii. It has over 200 rows and I'm looking to run viewsheds from each line, without doing it ...
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1answer
39 views

Compute number of days with snow

I have a project and I want to map the effective number of days with snow cover for a year in some mountain area. Until now, I have processed the MOD10A2 (8 days snow cover) product derived from MODIS ...
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30 views

How to check the resolution of converted raster file

I have a raster file whose resolution I need to change to 0.5. I do this using this: g.region rast=my_raster res=0.5 After running this command, how do I verify whether the resolution has actually ...
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14 views

v.clean in QGIS Python console

I have tried to use v.clean and v.clean.advanced (by GRASS GIS) within a script in QGIS, and was not able. I followed instructions here:, but was not able to do so. I got message: "No module named ...
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27 views

Why is the raster information No Data value set to -1.#IND?

I have a couple rasters that have been atmospherically corrected using the "landsat.toar" tool in Grass. When these rasters are output and I open up their properties in ArcCatalog, the NoData Value ...
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32 views

QGIS – Raster Calculator: Using flat (no data) areas of an aspect-raster in the raster calculator

I´m playing around with the Raster tools, following more or less the qgis-tutorial but using my own data. When I calculate the aspect of a DEM, flat areas are (logically) left without data. However, ...
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27 views

Does somebody has a Python script for a Multiple Flow Algorithm?

I´m looking for for a python script for a multiple flow algorithm assigning flow to all lower cells from one central cell. This algorithm is part of the r.terraflow and would need it to start at a ...
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2answers
20 views

Adjacency matrix in GRASS

I have a line shapefile that I use as network. I connect a set of point to it using "v.net operation connect" command. . My questions are: (i) how can I get the list of neighbors for each ...
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18 views

GRASS r.out.mat memory issues

we have built a model with pythn/GRASS that calls the r.out.mat module. The area is quite large 25,000x25,000 cells. The machine we are running it on is Windows 7 machine with 16GB of RAM. After a ...
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63 views

What is the typical v.surf.xxx exicution time?

What is the typical v.surf.xxx exicution time? I am trying to run v.surf.bspline on a set of ~1600 points. It has bee running for about an hour now and is stuck at spot indicated in the image. I ...
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49 views

Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
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31 views

NVIS module not found in QGis

When I try to use the nvis module in Grass, QGis, pops-up a warning window saying "Module nviz not found". how can I solve this issue and use the nviz?
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31 views

How to modify existing grass gis tools and run them in QGIS?

I would like to take an existing tool of the grass tool box and modify the code to the specific needs of my task. As I´m struggling to start some kick-off would be great. How to access code? What do I ...
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33 views

Empty signature file after i.gensig in Grass (SOLVED)

I'm trying to make a supervised classification in Grass 6.4.3 under Linuxmint 16. After digitizing the training areas, I transformed them from vector to raster. Then I've done the following: just in ...
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18 views

r.composite gives blank image output in GRASS GIS

While running r.composite in GRASSGIS GUI command the image formed looks absolutely blank. The data I used is listed here below. IRS-LISS III Multispectral coverages. (i.e. band 2, 3 and 4 for Blue, ...
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2answers
112 views

“Missing dependency.This algorithm cannot be run :-(” QGIS + GRASS Windows 7

Windows 7, OsGeo4W pack installed including QGis 2.4.0 and GRASS. I Qgis when i try to execute a GRASS geoprocessing algorithm i get this popup: "Missing dependency.This algorithm cannot be run :-( ...
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21 views

Help me to understand how i.fusion.brovey works in Grass 6.4.3

I'm using Grass 6.4.3 in Linuxmint 16. I don't have a very big problem but I'm trying to understand what is Grass doing, if I'm applying the process correctly and if there is something wrong with my ...
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30 views

r.topidx error: required parameter output not set

I'm calling GRASS r.topidx from QGIS 2.2.0. I can get other tools to work on the DTM, for example r.watershed. But r.topidx I get the Oops message: Oooops! The following output layers could not be ...
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qgis: module crashed or killed

using Grass 6.4.3. via Qgis 2.2.0 Valmiera (standard installation package): Why would Grass modules suddenly produce a "module cashed or killed" error. specifically in relation to r.surf.idw2 and ...
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44 views

GRASS GIS: auto-completion fails in commande line

I'm running GRASS GIS 6.4.3. on Win 7, SP1, 64 bit. The path to my grass-DB is: D:\grassdb Within the GRASS GIS Commande Line, if I press the tab-key to auto-complete only folders, files and ...
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21 views

GRASS workflow for volume calculation

i am attempting a volume calculation using the route of 2 dems (upper and lower) and trying to subtract the difference. workflow as follows: A. rasterise vector contours (v.to.rast.attr) B. create ...
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21 views

QGIS GRASS vector simplification creates duplicate data rows

When simplifying polygons in QGIS (2.2.0) with the GRASS v.generalize tool the resulting layer duplicates some data rows many times. A shapefile of 657 zones/data rows: .. is simplified to one ...
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50 views

Background (sky/terrain) of a viewshed

Is it possible to determine whether a point feature of a particular height would be backed by sky or by terrain? I've done the viewsheed analysis of a wind turbine. Now I would like to make a raster ...
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27 views

Error G_Calloc v.to.rast

Using the grass GUI I get this error message: ERROR: G_calloc: unable to allocate 2004389888 * 8 bytes of memory at raster.c:71 What can i do to remedy this?
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77 views

How to use python to set a variable to a value from a vector attribute table for GRASS

I'm adding to a python script for GRASS v.transects.py. I want to set a variable to equal a value from a field in the vector's attribute table using a for loop to cycle through each row. This is one ...
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24 views

GRASS raster map types: UInt16 and Float64

i am in the processing of using r.out.gdal to export DEMs from GRASS into QGIS this is the output of the first try: using UInt16 as the data type. r.out.gdal input=DEM0maslTopog@UTM_35S ...
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14 views

problem r.walk region GRASS

I'm getting troubles to run r.walk. If I run r.walk in this region: projection: 3 (Latitud - Longitud.) zone: 0 datum: wgs84 ellipsoid: wgs84 north: 33:39:03N south: 29:16:03N ...
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19 views

can grass modules work separately

Grass is very useful tool for pre processing of imagery.i want to use i.atcorr module separately.will it be possible. i have compiled using .cpp files(AerosolConcentration.cpp, ...
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23 views

Use python to execute GRASS module v.distance

I have successfully use python script to import a line shapefile and a point shapefile into GRASS, and the following are their attribute table in QGIS, line shapefile point shapefile Now I want ...
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82 views

libgdal1 and libgdal1h conflict

I am on Ubuntu 14.04. When I am installing PostGIS-2.1, it's asking for libgdal1 library. But when I am installing libgdal1, it's removing grass and gdal. Can someone please guide me how to install ...
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80 views

QGIS GRASS plugin missing!

I just installed QGIS version 2.2.0-Valmiera on my mac with OS X. First I installed all required frameworks. QGIS is running, but the Grass plugin is not existing. In the toolbox the grass tools are ...
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92 views

QGIS 2.2.0 GRASS not worked

I use QGIS 2.2.0 on Windows 8 64 bit. I try to install use Standalone installer and OSGeo4W and still get the error And then i start GRASS C:\Program Files (x86)\GRASS 6.4.2>grass64 ╬╪╚┴╩└: ...
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26 views

GRASS GIS 3D - Inconsistent number of attributes

I am trying to automate my 3D plotting of GRASS GIS 7 results, also to make them more consistent in size and view angles. So for m.nviz.image elevation_map=DEM -a mode=fine resolution_fine=1 ...
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17 views

QGIS GRASS plugin: r.composite quality loss

When using the r.composite tool within the GRASS plugin in QGIS, the result raster has a cell size of 150x150 while the input rasters have a cellsize of 30x30. Can this be overcome somehow or is this ...
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24 views

GRASS GIS v.in.ply

I'm trying to import a .ply file from MeshLab 1.33 into GRASS GIS 7.0 using v.in.ply addon, but I get the error message: ERROR: List index must be integer, is uchar This appears to be referring to ...
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16 views

Run this module in GRASS 6.4.3 command line in Windows 7 or QGIS Grass Module

I have GRASS 6.4.3 running and working in windows. I would like to use this script (http://grasswiki.osgeo.org/wiki/AVHRR) Scroll down to Import to see the code. I have the correct EPSG set but ...
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33 views

Problems running grass.mapcalc

I am using the GRASS Python Scripting Library on Ubuntu 14.04 with the packages available from the Universe repository. I have the following block of code: try: ...