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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3
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1answer
715 views

How to get the Flow or directional raster map using GRASS?

Aside from using r.fill.dir in GRASS, is this the script to produce the Flow or directional raster map? Is the output for the script the following graphic? http://grass.fbk.eu/grass63/screenshots/...
1
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0answers
38 views

GRASS unable to download any extension from GRASS Addons

I'm trying to install some add-ons to GRASS, but each time I try to download an addon, I'm getting the same error: g.extension.py extension=v.autokrige svnurl=http://svn.osgeo.org/grass/grass-addons/...
5
votes
2answers
3k views

How to correctly install QGIS 2.8.3 with GRASS plugin on Ubuntu 14.04?

I already tried to install QGIS 2.8.3 using the procedure described on: http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubunt, but grass-plugin do not compare on plugin list! I tried ...
2
votes
2answers
110 views

Missing v.in.ogr module of GRASS in QGIS Processing toolbox?

I am a new user to QGIS/GRASS and I am having a problem utilizing GRASS. I have several files that I generated in QGIS that I want to import into GRASS so I can use some of the Grass modules. ...
2
votes
1answer
76 views

windows can't open the file, v.in.ascii

I am using GRASS 7 for windows, and I'm having trouble running v.in.ascii, although I'm fairly sure I've run it successfully before. When I run v.in.ascii, I get an error: Windows can't open this file....
2
votes
1answer
33 views

Using wild cards in GRASS to remove files

I have a bunch of files on a GRASS location, all named temp_something, that I want to delete. I tried to use the g.remove tool using the multiple option and typing temp* in, but it doesn't work out, ...
4
votes
3answers
76 views

How to list the available GRASS modules in command line

Using GRASS shell, I know that I can use the -help suffix to get information about a particular module. E.g. r.relief -help will return this: Description: Creates shaded relief map from an ...
1
vote
1answer
297 views

QGIS 2.10.1 GRASS Processing algorithms not working

I just did a fresh install of QGIS 2.10.1 from the qgis repos (Ubuntu 14.04). I also have grass70 installed (through ubuntugis-unstable). I can see the GRASS7 commands in the processing toolbox panel,...
3
votes
0answers
41 views

Calculating a specific distance from points along a network - GRASS

I'm currently using the v.net.iso function in GRASS (no access to network analyst in ArcMap). Does anybody know of a way to export the result to shapefile so that you have an individual line feature(s)...
6
votes
3answers
723 views

Network distance computations using GRASS

I'm an ArcGIS user who's interested in learning to use GRASS. Can anyone point out resources that will help me in learning how to obtain network distances between (1) residential locations (points) ...
3
votes
1answer
121 views

Get ID for each single v.to.points point in GRASS?

How do I get for each v.to.points point an ID in the database (DB). So far I splited the line (each 10m) but it returns only one DB entry for each original line. v.db.select line cat|Id|Name 1|1|...
1
vote
0answers
43 views

Grass i.landsat.acca says image is cloud free but it is not

I'm working on an area in Amazonia with high cloud persistance which makes global data on land cover quite useless at small scales, so I wanted to learn to process my own Landsat images, with GRASS ...
4
votes
3answers
826 views

3d vector and geometry operations in open-source GIS

There is some really good open-source software available to work with 2D vectors. For example QGIS has operations like buffer / clip / dissolve / select by location / join attributes by location... ...
4
votes
1answer
67 views

GRASS GIS temporal raster individual layer statistical summary

I have created a temporal raster in GRASS GIS which has 90 layers. I would like to extract the mean of each raster layer and export it as text file. Right now I have to export the rasters as GeoTiffs ...
2
votes
0answers
28 views

Attribute table update after v.split on GRASS GIS [duplicate]

So I just used v.split to create shorter segments (with just 2 vertices) of my contour lines. I was left with about 22000 lines but, when I open the attributes table, I find no more than 45 entry ...
2
votes
1answer
62 views

Importing shapefile into GRASS, and multiple new rows appear in attribute table

I am importing a GADM Global Administrative Areas shapefile into GRASS (using QGIS 2.8.2 interface). When I do this, multiple additional rows are created in the attribute table. It goes from this: ...
5
votes
1answer
168 views

How to get r.drain to run in QGIS/GRASS?

I use the GRASS GIS extensions for QGIS (QGIS version 2.12.3 with GRASS 6.4) and I have a problem with the r.drain algorithm: I simply cannot make it work with a given starting point as a vector point....
32
votes
4answers
868 views

Generating equal sized polygons along line with PyQGIS?

I would like to create polygons along a line to use them for AtlasCreator in a next step. ArcMap has a tool called Strip Map Index Features. With this tool I can choose the height and width of my ...
1
vote
1answer
57 views

Solar radiation flux at 5 minute interval using GRASS GIS r.sun

I have been trying to estimate instantaneous total solar irradiance(w/m2) at five minute interval for a day (eg. 21 sept). I can do this in SAGA GIS by using "moment, mode 1" and running the solar ...
4
votes
0answers
330 views

Error when using r.watershed in QGIS 2.10.1 with Grass

I am running r.watershed within QGIS processing the I get the error below. I draw your attention to: GRASS_INFO_WARNING(2205,1): Subprocess failed with exit code 256 GRASS_INFO_END(2205,1) ...
2
votes
1answer
119 views

Capturing Output Messages from GRASS when Running Python Scripts

Thanks to the excellent documentation here: https://grasswiki.osgeo.org/wiki/Working_with_GRASS_without_starting_it_explicitly#Python:_GRASS_GIS_7 I've figured out how to access GRASS modules in ...
2
votes
1answer
52 views

Panchromatic Image Classification GRASS GIS

How to perform an unsupervised classification of a single panchromatic satellite imagery in GRASS GIS? I tried it many times but I keep being prompted for a second image or other images in the sub-...
1
vote
0answers
87 views

Execute GRASS command within QGIS python console

We try to calculate catchments with the r.water.outlet function from python console. To do so we use the following code: import processing rlayer = QgsRasterLayer("/my/path/DrainageDirection.tif", "...
3
votes
2answers
569 views

How to make GRASS 7 addon available in QGIS 2.12?

I stumbled across the GRASS-Tool i.segment but could not find it in my QGIS processing toolbox. I found out that it is an addon for GRASS 7 that I already installed in GRASS 7 standalone. How can I ...
3
votes
1answer
144 views

Get results from using GRASS algorithms with the QGIS processing tool

I am trying to write a plugin in QGIS that uses at some point a GRASS algorithm : "v.split.length", accessible by using the processing class, and here is how I am using it : processing.runalg("grass:...
7
votes
1answer
1k views

Calling GRASS modules in pyQGIS?

I wish to use a Grass module (v.to.db) in QGis, without the grass toolbox. I tried with the Python console, but to no avail : Using Sextante plugin but obviously it didn't know all the grass ...
1
vote
2answers
59 views

i.landsat.toar not working and returning error [duplicate]

First time using grass. I need to convert DN to reflectance. Imagery -> Sat. images tools-> i.landsat.toar. But when I add raster name. I get error. Im using landsat 8 images WARNING: WARNING: ESUN ...
1
vote
1answer
56 views

How can I add r.local.relief to the QGIS Processing Toolbox?

I'm working with QGIS 2.12 and GRASS 7.0.3RC1. I'm making a model using the model builder and trying to add the GRASS addon "r.local.relief" in my QGIS model, but the addon does not show up in the ...
2
votes
2answers
51 views

How can I extract flat surfaces from a DEM with GRASS GIS?

How can I use GRASS GIS to get the flat surfaces in this DEM into polygons? The picture is used to show the clearly defined flat surfaces.
0
votes
0answers
48 views

Converting LandsatMSS DN value to reflectance using GRASS71 [duplicate]

I'm working with a Landsat image MSS by using Grass 7.1,the image's name is LM40080531988146AAA03 with format .tif, the problem is that I want to convert DN value to radiance/reflectance. I'm using ...
2
votes
2answers
207 views

Merging contour lines along tile boundaries

I am working with the CANVEC data set. The data in canvec is broken up in to mapsheets. eg. 116B04. I have data covering the entire province of the Yukon. I have merged all the data in to one ...
2
votes
0answers
52 views

Avoiding edges using GRASS generalization?

I'm trying to process the national wide land cover data into vector polygons. In order to be quick I separate the data into several tiles and process them in parallel. process flow is : 1. v.in.ogr ...
6
votes
1answer
7k views

Converting Shapefile to MySQL?

I have used Grass GIS imported a .shp file; I now want to export this file to MySQL. I understood that MySQL will contain the function of all three the files necessary in a Shape file system (.shp - ...
3
votes
0answers
55 views

Wrong area using Albers Equal Area Projection in GRASS for Java, Indonesia

I am just getting to know GRASS 7.0 and I am struggling finding a good projection to work on a spatial analysis of Java, Indonesia. I am new to the forum, so if information's are missing for a better ...
1
vote
2answers
83 views

Vector to raster conversion [solved]

I'm using GRASS but, in case, I'm also familiar with R and QGIS. I'm trying to convert a vector area map into a raster one. My problem is that the resolution of the raster is too low (and I can't ...
2
votes
2answers
135 views

How to calculate the distance to the nearest water source?

I have a polygon hydro layer of my study area and am trying to calculate the distance to nearest water bodies from my site. Since my site are 2km*2km grids I am not sure how to calculate it? Whether ...
0
votes
0answers
25 views

A vector object not being replaced in temp folder when using 'for' loop in R

I am currently running GRASS GIS through R interface and got stuck at this point; where I am using a 'for' loop in R, and the code is as follows: for(i in 1:nrow(Snapped_SSP_DSN)) { writeVECT6(...
4
votes
2answers
80 views

How can I calculate flow length in QGiS/GRASS?

I have these rasters: DEM Flow Direction Flow Accumulation I would like to calculate the flow distance of every pixel to the outlet of a basin. In Arc-GIS, I can use the flow length. But I don't ...
7
votes
3answers
142 views

How do I count the number of vector lines that pass though a given raster cell?

I am working on a project (currently in GRASS7 though I'm not against exporting to Arc or R or other software if necessary) where I am generating thousands of shortest cost paths (using the r.walk and ...
4
votes
1answer
952 views

Solar irradiation calculation using r.sun

I am trying to compute the global solar irradiation for a region and the run times seem to be a bit too high. I have as inputs a Digital Surface Model with the buildings and a Digital Terrain Model ...
3
votes
1answer
105 views

Calculate Volume over sloped ground in GRASS GIS

I am trying to do some volume calculations on a DEM with GRASS GIS. However, I believe r.volume measures everything from 0. The ground underneath the pile I'm measuring is sloped. I would ...
0
votes
0answers
24 views

GRASS: strange classification output and reject map from “i.maxlik”

I am trying to perform a supervised classification with "i.maxlik". I have three bands: 1) elevation (a dem); 2) reflectance (derived from Landsat ETM+ band4); 3) cumulative solar radiation (derived ...
18
votes
1answer
300 views

Is it possible to generate a boustrophedon pattern which fill a vector Region with GRASS?

Is it possible to generate a boustrophedon pattern which fill a vector Region with GRASS? I have a vector region in GRASS. And I would like to generate a vector (a polyline) being the bostrophedon ...
2
votes
1answer
55 views

Error while executing v.rast.stats command in grass plugin in qgis

I have a vector polygon which I imported in grass. I also have a raster from which I have to extract the value. I ran v.rast.stats command in QGIS 2.12. The command was executed with error. The error ...
4
votes
1answer
120 views

What happened to the GRASS Browser in QGIS?

In the past I could display the imported layers in the GRASS toolbox within QGIS. This was possible under the tab "Browser" as you see in the image. Lately I'm missing this tab. The QGIS version is ...
1
vote
1answer
51 views

Unable to open shapefile with GRASS GIS? [closed]

Is GRASS GIS able to work with a shapefile (*.shp)? I can´t open my shapefile (328000Kb) in that program. I want to dissolve a shapefile in GRASS because on QGIS the process is very slow.
1
vote
0answers
69 views

Making GRASS GIS 7 Ubuntu bash file work on Windows 7

I have created this bash file (.sh) while working on watershed analysis stochastic simulation in GRASS GIS 7.0.2RC1, which is running on Ubuntu. It worked perfectly and I received the correct results. ...
8
votes
5answers
7k views

How to set all pixels with value <= 0 to “nodata” in DEM raster?

I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the ...
1
vote
0answers
35 views

i.spectral tool error

system description: Windows7 32 bıt OS, Grass GIS 7.0.0 Gnuplot 5.0 Solution attempt 01: On the basis of following thread, commented out said path check lines from i.spectral.py script: https://...
1
vote
1answer
79 views

how to calculate the mean value of pixels of a raster in Grass plugin in qgis?

I am using grass plugin in qgis 2.12. I have to estimate the average value of all the pixels but don't know how to do it.