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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1answer
21 views

Error using Grass v.clean

I am trying to clean topology of a TAB file in QGIS 2.14.4 and it returns an error message as below The weird thing is, I am able to execute this okay on my machine but not my colleague's. The other ...
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0answers
41 views

Resolving geometry errors in QGIS

I have a shapefile where the geometry is a mess, lots of gaps, slivers, and holes. I need to correct these geometry errors, but I am having trouble with the process. I have read the pages here, here ...
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9 views

calculate watershed area for many points

Is there an efficient way to calculate the watershed area for many points using GRASS without looping through all points? My points lie anywhere on the stream segments not just at the junctions. This ...
1
vote
1answer
30 views

How do I connect my Python script external to the Grass GIS 7 program in Windows 10?

I've tried to find resources online to link and run my Python script externally from Grass GIS 7, however, I have not been successful. I found resources here that provide instructions (e.g., https://...
1
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2answers
190 views

Error using Grass v.net

I'm trying to connect my network to a points layer with a threshold of 4500 meters. I have about 11000 or so entries in my polyline and about 24 in my points layer. I have alreday used v.distance, ...
0
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1answer
14 views

GRASS dependecies issues in Windows QGIS (i.vi for instance)

I have QGIS (2.14.3) and GRASS (7.0.4) desktop installed on windows 7 and have successfully installed the "GRASS" plugin in QGIS (using plugin manager). However, some of the GRASS dependencies, such ...
3
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3answers
580 views

Can a raster map in GRASS be saved in JPEG/BMP format?

I'm trying to save a raster map in GRASS in jpeg/bmp format without using the GUI for d.out.file/d.save. Is there a script to do it? I tried r.out.gdal but it produced a map that is black and white.
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0answers
19 views

GRASS 7.3 r.fill.dir Does Not Create Output Raster

I am running GRASS 7.3 on Mac OS X El Capitan (2.9GHz, 8GB RAM). I have had to disable SIP in order to run it, but it works. I am hoping to perform some hydrological analyses on a few DEMs. My DEMs ...
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0answers
12 views

Advice on which open-source GIS program to choose for object oriented feature extraction [on hold]

I need to extract polygon features from a series of raster images I have. I think that object oriented feature extraction might be the way to go, i.e. segmenting the image, and then doing an ...
1
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2answers
293 views

How to compile QGIS from source with Grass?

I recently decided to reinstall QGIS and build against the latest version of GDAL - something I have been putting off for ages because I suspected it would be a nightmare. Lo and behold it has been, ...
1
vote
1answer
28 views

Run processing (GRASS) algorithm as administrator

I am trying to use GRASS algorithms in a plugin of mine, in order to improve the quality of a shapefile containing lines that will be used as a graph later. The first algorithm I want to use is the ...
2
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0answers
37 views

QGIS GRASS: Error when converting vector to raster

I am trying to convert a vectorial layer (a grid of regular points with values, representing probabilities, associated to each point). I tried to use QGIS, but I got this error: ERROR 1: Attempt to ...
1
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1answer
32 views

Grass GIS messed up projection

I needed to load a shape in GRASS GIS to use the v.clean.snap function. The .shp was first viewed in QGIS, projected in 3857 or 4326, I don't remeber. After the adjustments in GRASS GIS I exported to ...
0
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0answers
16 views

AniMove error “Wrong value for parameter GRASS7 folder”

I installed animove in QGIS 2.14, then I go to Processing -> Options, Under the Providers section find Animove, Under Animove check Activate. I do this and then press OK. Error message "Wrong ...
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2answers
64 views

Error installing addons in GRASS 7.0.2: File is not a zip file?

When I attempt to install an addon in GRASS Setting->Install Extension from Addons and select the addon i want from the list (r.stream.order) i get the following error: "ERROR: File is not a zip file: ...
0
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0answers
18 views

Add r.null functionality to GRASS toolbox algorithms in QGIS

I'd like to be able to use GRASS's r.null operation in the QGIS processing toolbox (not via the GRASS plugin). However, it doesn't seem to be available. How would I go about adding code to allow for ...
0
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0answers
16 views

Does the random number generator used by v.random return duplicates?

Using v.random, r.random, etc., can the same sight/location be selected? Meaning, can a location show up more than once?
1
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0answers
21 views

SPOT 1 HRV Atmospheric correction in GRASS GIS 7 returns NULL values

I'm having trouble using i.atcorr in GRASS 7. I am using 3-band SPOT 1 HRV image (Green, Red, NIR bands). Performed the i.atcorr for each band using the 6S parameters below (last parameter changed ...
2
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2answers
213 views

Suitable Raster processing methods to extract field boundaries from images

I'm trying to extract field boundaries and features from a lot of aerial images of agricultural land - and avoid digitizing these features manually. I've managed to get a crude raster file of the ...
3
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0answers
269 views

Performance difference between focal statistics (ArcGIS) and neighbor (GRAS or QGIS)

I tested minimum, maximum, and average neighbor (circle radius = 161 pixel) using ArcGIS, GRASS and QGIS: ArcGIS (10.1): it takes only one minute GRASS (6.4.3): it takes 123 minutes for every output ...
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1answer
93 views

QGIS 2.16 GRASS geoalgorithms don't work?

I have problem again almost like version QGIS 2.14. I did not solve the problem. QGIS 2.14 GRASS geoalgorithms don't work? I install C:\MinGW and now QGIS grass geoalgorithms don't work? There is ...
32
votes
5answers
11k views

How to smooth a DEM?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough becouse the area is near flat and the DEM is 90m in ...
2
votes
1answer
345 views

Using Spyder IDE to develop python for Grass GIS, get 'ImportError: No module named grass.script'

I am trying to use Spyder IDE to develop a python script using python library from grass-6.4.3. I run the script below, and get 'ImportError: No module named grass.script' I am using python 2.7, ...
1
vote
1answer
24 views

importing files from grass mapset to QGIS Layer Panel

I am performing an NDVI calculation against 2 sets of rasters. One produced by LANDSAT5 the other by LANDSAT8. r.mapcalc "L8_NDVI = float(L8Band5 - L8Band4) / (L8Band5 + L8Band4)" The L8_NDVI file ...
10
votes
1answer
496 views

Using ArcPy and PyGRASS tools in same Python script?

I´m trying to write a Python script, that includes different ArcPy / ArcGIS commands and want to combine it with GRASS geoprocessing tools. Unfortunately importing the GRASS libraries doesn´t work. ...
0
votes
1answer
11 views

r.statistics throws invalid reclass rule error despite assigning null to unique value

Trying to run r.statistics on two raster layers, one a layer of distinct zones produced via r.clump (stands) and one a layer of all ones (ones). The areas outside of the immediate region of interest ...
0
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2answers
21 views

Problem with r.grow.distance on GRASS

I would like to use r.grow.distance on a raster map. I rasterised a shapefile (about 50 cities in a region) and we can see them on the raster map. Yet, when I launch r.grow.distance, I have a ...
2
votes
1answer
231 views

How to use GRASS v.kernel to calculate point densities along a network?

In a road network, I need to select the segments where a minimum of 5 dots occur (1 dot = 1 address) over a distance of 100 m (the image attached illustrates my question). I'm trying to use GRASS v....
0
votes
1answer
20 views

r.fill.dir blocked

I am trying to fille a DEM downloaded by Geobolivia http://geo.gob.bo/. The r.fill.dir module in QGIS/GRASS toolbox blocked few minutes after I launched it for the DEM. It is very strange as, for ...
2
votes
2answers
464 views

Error Importing dbf File Into GRASS

I am working on an assignment which requires me to connect to a database, then import a dbf file into the database using the command db.in.ogr (as can be seen below). However, GRASS simply won't ...
3
votes
1answer
41 views

GRASS on QGIS is generating new CRS

I am experiencing a strange problem by using the GRASS toolbox on QGIS 2.14.3 Essen. Even if in settings>options>CRS I select to use the project CRS when creating new layers, the results of GRASS ...
1
vote
1answer
17 views

geology problems: three-dimensional fault line - r.plane (GRASS) from polyline

I should use the r.plane script (GRASS) but imputing a polyline (trace of my fault line) and not a point; is this possible? I could use batch process, but I should be charged a lot of points and then ...
1
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0answers
15 views

Resolution changes when exporting raster from GRASS to Arcmap

I have a raster file of rainfall (floating) in GRASS that I want to export and open in arcmap. If I look for the raster file in GRASS, it has Rows: 140 ...
1
vote
1answer
9 views

How to change / switch mapsets in GRASS using cmd

I am using GRASS 7.0.4 I have created a new mapset to the LOCATION using cmd in it. But unable to switch back to old mapset. can anyone guide me??
8
votes
1answer
113 views

How do I Spatially Partition a whole lot of points?

I have location data of customers, with over 130 million records, spread all across the country. This is a Spatial Table in PostGIS I want to now partition the entire country into 'service areas', ...
1
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0answers
14 views

GRASS v.net.iso does not include all lines

I want to define catchment area for bus stops in small city. As a result of v.net.iso in QGIS with GRASS I don't get all highways in that city. Here are my steps: importing above layers into GRASS ...
1
vote
1answer
217 views

trying to calculate volume using r.volume GRASS - error message

I am trying to calculate volume using GRASS plugin in Qgis using module r.volume however the attached error message keeps appearing. Any ideas?
0
votes
1answer
193 views

How does i.fusion.brovey in Grass 6.4.3 work?

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 ...
4
votes
2answers
226 views

Is r.cost equivalent to diffusion interpolation with barriers?

I want to perform interpolation using cost distances rather than euclidean distances similar to Greenberg et al. (2011). In that paper they use r.cost in GRASS to compute cost distances for each ...
0
votes
0answers
17 views

How to obtain accumulation map from r.stream.extract

I would like to obtain the accumulation map that is produced within r.stream.extract when extracting streams and then use it as input for r.stream.order (as described at the man page of r.stream.order:...
8
votes
1answer
187 views

Can GRASS compute the line graph representation of an input graph?

I'm interested in computing a line graph for an input graph, preferably in GRASS since I'll be using other GRASS network analysis tools afterwards. I couldn't find any reference to line graphs in the ...
0
votes
1answer
1k views

Grass Gis 7 does not start in OS X 10.11 El Capitan

Recently I installed the El Capitan upgrade but unfortunately Grass 7 (from the official repository - Grass Gis for Mac) does not start any more. I also re-installed all required frameworks, but I had ...
0
votes
1answer
247 views

grass - add on problem

I can't install the addon in grass 6.4.3 to my linux mint. i've already installed the SVN and than it says: GRASS 6.4.3 (fabian_idrisi):~ > g.extension r.fuzzy Fetching from GRASS-Addons SVN (be ...
6
votes
1answer
364 views

Using GRASS algorithms in Sextante under ArcGIS Desktop? [duplicate]

Sextante for ArcGIS comes with SAGA modules. I know that I can use GRASS algorithms in Sextante under gvSIG. But how can I use GRASS algorithms in Sextante under ArcGIS Desktop? I tried to look ...
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0answers
23 views

grass algorithm changes integer to fixed length

using grass v.clean in the graphical modeller it changes all integer values from the original file to int with length 9 Is this a standard behaviour? Can this be avoided? The details of the grass ...
2
votes
1answer
33 views

GRASS Toolbar for QGIS missing the tools I expect to see

I am trying to learn GRASS and QGIS using the instructions here: https://docs.qgis.org/2.6/en/docs/user_manual/grass_integration/grass_integration.html. I am running on Windows and open the version of ...
0
votes
2answers
27 views

GRASS iterate over multiple shape files using g.region

I have a shapefile called Ahmednagar. I have daily rainfall data from 1997 till 2008. I want to sum total rainfall from 152 till 273 day for each year for 1997 till 2008. This is how I do it. g....
2
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0answers
26 views

Comparison of % change in two photos with GRASS

I have two aerial photos of the same location taken at two different dates. Is there a way to compare the % difference between those two images using GRASS or is there a better tool? Sorry, also if ...
2
votes
2answers
138 views

Grass tools not working in QGIS 2.14.3-ESSEN, OSGEO4W

Windows 10 QGIS 2.14.3-ESSEN OSGEO4W install (current) 64-bit Processing toolbox. Grass tools do not work Neither 6 nor 7. 6 makes sense as I do not see OSGEO4W installing it but 7 tools are ...
0
votes
1answer
33 views

Fast, simple assignment of flow directions to flats in GRASS

I have some enormously huge DEMs which I'd like to assign flow directions to. These DEMs are guaranteed to have no sinks, just flat areas. It seems as though the only ways of assign flow directions ...