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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Extract Elevation of Points from DEM using Python QGIS or GRASS

I am utterly new to GIS, so please bear with me if I am providing incomplete information here. I have a DEM file (.dt2). What I am looking to do is as follows: take a series of points specified as ...
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148 views

GRASS failed to import ESRI ASCII grid

I'm a new user of GRASS 6.4.3 and I wanted to import ESRI ASCII grid. Raster file was unzipped, and in r.in.arc window I specified name for output, storage type etc. After it has run, raster didn't ...
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234 views

Problem with Bash loop in GRASS GIS

I'm new to GRASS GIS and programming and I'm running into a lot of what I imagine are beginners problems and something similar to this has been asked before, but not In a way that I understand. I'm ...
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311 views

How to specify column names with v.in.ascii

I have managed to import a CSV file into a points vector file using GRASS v.in.ascii v.in.ascii --o input=test1.csv output=test2 format=point fs=, skip=1 x=2 y=3 z=0 cat=0 This is test1.csv ... ...
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3answers
221 views

Looking for large GML files containing vector polygon data

I have few vector data files with 500 to 700 MB GML files. But I am looking for files larger than these preferably 1 GB, 2 GB. It would be helpful if somebody can provide some pointers regarding the ...
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76 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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184 views

r.viewshed - Can't find with Grass toolbox

I'm trying to use r.viewshed and have got Grass installed but can't find it anywhere! under toolbox, I click 'Grass commands (152 geoalgorithms) and have a choice of imagery, raster, vector, etc, ...
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346 views

Matlab script - how to access from/run in GRASS GIS?

I am currently working on shell script in GRASS GIS and Ubuntu. At some point, I must run a calculation (based on an ascii grid) that I have available as Matlab script and .exe (created from Matlab I ...
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548 views

How to batch merge rasters using FOSSGIS tools?

I'm working with QGIS 1.8 (gdal 1.9.2) and GRASS 6.4.3...but on Windows 7. I "just" want to merge my raster. I've got a folder with 50 GTiff raster from Lidar data. The aim is to merge raster ...
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876 views

3D Interpolation using point cloud in GRASS GIS

I've imported a set of 3D points (z,y,z) into GRASS GIS. I'm having trouble: a) visualising my dataset in 3D using nviz or the standard data viewer (I can only get a 2D plan view of my data) and, b) ...
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870 views

Compiling Grass from Source in Ubuntu

Hi a while ago I drafted a semi-universal guide on how to compile GRASS GIS on Ubuntu. Because I had enough emails asking more details I thought to post it here for everyone and if possible to ...
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57 views

GRASS parser() error

I'm trying to use GRASS on python 2.7, but I'm having some problems at setting my script on IDLE, then I'm getting an error at parser() function: Here is my script: import os import sys gisbase = ...
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62 views

Paths with least elevation gain

I have a DEM of a city with numerous hills and a shapefile of the city streets. I want to find the five paths from a low point A to a high point B on the street network that involve the least ...
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107 views

Can't access GRASS tools in QGIS [duplicate]

I'm running QGIS 2.6 on OSGeo-Live 8.4 Virtual Machine based on Lubuntu 14.04. I've set up a GRASS (GRASS GIS 7) environment in QGIS, and I have a merged .tif file of LiDAR images open in QGIS, so I ...
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68 views

comparison of atmopsheric correction methods

I have noticed that dos methods for atmospheric corrections are in the section of radiometric correction (i.toar) on grass gis.Does that means that dos is a method doing radiometric and atmospheric ...
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126 views

GRASS convert raster to points

I have tried to convert a raster to points using this syntax: r.to.vect input=g_kelowna_merged@kelowna_mapset output=g_kelowna_points feature=point I have tried using the GRASS interface in QGIS and ...
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133 views

Ls factor, flow accumulation, watershade, relief in Quantum GIS 2.2

I'm a beginner quantum gis. I want to make the LS factor of 30m DEM that I have merge and set the projection in wgs 84/UTM zone 49S (EPSG ; 37249). I'm having a problem when trying to create relief ...
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154 views

Removing salt and pepper effect

In a land cover raster (categorical map) that is a product of classified satellite image, what is the best way to remove "salt and pepper" effect from the image after classification. I am not ...
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103 views

How to import and layer stack seperate ndvi bands to grass gis?

I have 20 separate single band NDVI files. I have to import this into GRASS and stack them into a single 20 band image. How can I do that?
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142 views

How to change the Map Units in Grass?

because v.segment measures all offsets in map units, i have to change it. (I want to put all of 50 meters a point) So I checked g.proj -p: -PROJ_UNITS------------------------------------------------ ...
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85 views

Discrete Waterpoints with Grass

I've been working with Grass GIS for about two months. I have to develop a method for the identification of target regions of small hydropower plants. Boundary conditions are a predetermined minimum ...
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156 views

v.generalize on massive vector data

I have a contour line file that covers the most part of north italy (shape is 0,6 gb) and I want to use v.generalize (snakes algorithm) on it. Because of the large file size, if I use Grass 6.4.3 I ...
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177 views

How to batch export using r.out.gdal command in GRASS

I created a list of files (NPPFILES) using g.mlist command in GRASS 7. Now I would like to export these files as .tiff files. I tried this command in GRASS prompt for files in $NPPFILES; do ...
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188 views

Qgis map composer shows a huge red cross

I can show this best by a picture: This cross also shows when I export it as raster or pdf. What is it and how can I get rid of it? I am using Qgis 2.4 and the map was done with the help of the ...
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328 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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43 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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551 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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261 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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33 views

GRASS module g.mremove returns irrational outputs

I want to use g.mremove to remove multiple files in my mapset, import os import sys sys.path.append(os.path.join(os.environ['GISBASE'], 'etc', 'python')) import grass.script as g import ...
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282 views

The same error message shows up while running GRASS command

I'm using GRASS 6.4.3(installed with OSGeo4W) under Windows 8.1 x64. When I type commands in the command console below, I often face these problems: type command which has "space", like:g.list ...
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3k views

How to use GRASS module to delineate watershed area?

Update#1:I changed to work under qgis 1.8, I only input the DEM file and run the r.watershed module, and I got this: I have a DEM file of one specified region, and I take the following steps to ...
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134 views

Two r.mapcalc calculations return a much bigger raster cell size than the input raster

I tried the following calculations with a GeoTiff sample, having a cell size of 25m: Calculating the togographic exposure (TOPEX) and estimating the mean topographic curvature Both, the resulting ...
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184 views

Area of a Cross Section GRASS GIS 7

I have a task I would like to solve with GRASS GIS 7, if somehow possible. I want to create a cross section from a landslide - and would like to calculate the area of that cross section/profile. Any ...
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719 views

GRASS in QGIS not working (windows XP)

I am unable to use GRASS algorithms in QGIS 2.0.1 (on windows xp). I've already configured the GRASS path. The algorithms seems to work correctly (I cannot see errors in the log), however in the end ...
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261 views

In grass v.drape works with points but not lines

I got an elevation raster map which I interpolate from a point cloud with v.surf.bspline. Then I digitize a couple of points in a new vector layer. With v.drape I'm able to get a height from the ...
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1answer
648 views

Basic raster map questions

My bigger problem is to convert a raster map to polygons. I've found some questions that give info and I'm trying to use GRASS GIS as part of that. However, I'm having some basic problems and I can't ...
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200 views

v.surf.idw on grass return : no data points found

I'm a newbie with grass and I'm using grass (6.4.3) with the GUI... running Ubuntu 13.04 for what it's worth. Here is my region : projection: 99 (Lambert Conformal Conic) zone: 0 datum: ...
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91 views

Error message starting gis.m in GRASS

I finally broke down and bought Neteler and Mitasova's book, Open Source GIS: A GRASS GIS Approach, because I need to learn command-line GRASS. On trying to work through the book's examples, I'm ...
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194 views

GRASS GIS related issues! [closed]

(1) How to create a multiband raster from a set of single band rasters (except when somebody talks about doing a r.composite). I attempted creating a raster3D and it turned out that it is not ...
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130 views

Problem with interpolation of 3D points in GRASS

I have a sample of 3D points (x,y,z) with tepmerature attribute. I can import my data as a 3D vector map. I want to create a volume of voxels by using v.vol.rst. When I use this module, this error ...
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102 views

Adding additional nodes to network in Grass GIS

I have created a network in Grass GIS (using v.net, nodes option). I then want to "disrupt" the network (i.e., create some road blockages) and add in nodes to the new line ends where road blockages ...
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1answer
132 views

Full Easting and Northing coordinates values cannot be encoded in GRASS r.water.outlet in SEXTANTE-QGIS

The Easting or Northing coordinate parameter accepts only 5 digits. The Easting and Northing values for my outlet are 6 and 7 digits long (integer). How can they be encoded in r.water.outlet? Can ...
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2answers
249 views

Handling MODIS NoData cells with gdalwarp

I'm using the gdalwarp tool to convert MODIS .hdf into GeoTiff files. I want to set the value of the nodata cells so that when I import the .tif image into Grass there is no black edge. I'm using the ...
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95 views

Grass 7 - where is r.regression.multi hiding?

I compiled Grass 7 on Ubuntu and all works fine - except, I cannot find r.regression.multi. I installed it, yet it is nowhere to be found in the drop-down menus; r.regression.line is there and works, ...
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114 views

GRASS v.db.update Concatenate Fields

I am trying to concatenate two fields into one new field in GRASS, but I am unable to get the syntax to work. Ideally, I would like "FIELD1" and "FIELD2" concatenated together in "FIELD3". All fields ...
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22 views

How do I add “padding” to features when applying d.out.file to map display on GRASS?

Thing is this. I've done up a script to automate some spatial interpolation and eventually output the interpolated raster and contour lines as an image of the map display. I'm doing this using ...
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302 views

Automatically apply topology rule to only selected portions of a .shp file?

I am looking for some examples/tutorials on how to apply a topology rule to only a selected portion of a shp file using a script in ArcGIS/GRASS. Using ArcGIS seems to always require an interactive ...
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183 views

Problem running i.gensigset in Grass. Any ideas?

It just returns ERROR: Unable to create signature file. It doesn't say why... Anyone had this before and found a solution?
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1answer
467 views

How to transform a DEM to a cartesian coordinate system?

I am using the script r.inund.fluv. I run the script with all the required parameters and it produced a lot or errors. I emailed the author of the script and he said that "I think you are not ...
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43 views

whats wrong with my exported raster reclassify map in grass?

I'm trying to export a reclassify map in grass to a Geotiff format to pass it to DinamicaEgo platform. I have 6 classes in grass but when I export it, the exported map show me 255 classes and they ...