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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2
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2answers
54 views

Create a new GRASS database in R with CRS projection

How to create a new GRASS database in R with CRS projection? I am able to create a new one using the following code but it is not projected require(raster) require(spgrass6) ...
0
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2answers
47 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 ...
0
votes
2answers
331 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 ...
1
vote
1answer
25 views

Set region with rounded values/coordinates

How do I set a region update with rounded coordinates. I usually set my region from a puffer around my points of interest and round up the north and east coordinates and round down the south and west ...
2
votes
1answer
46 views

Problems to use v.what.vect in GRASS7

I have problems to use the function v.what.vect and I'm not sure what is the issue. I have a simple forest polygon and try to determine if a point is in the forest or not. # check the output of the ...
1
vote
2answers
391 views

Error in r.terraflow

I used r.terraflow.short in GRASS, but it displayed this error: r.terraflow.short elevation=raster_bulacanElevation \ filled=raster_bulacanElevationFlooded1 \ ...
1
vote
1answer
58 views

QGIS: Grass Tools: Least cost path using r.drain generating flawed results

I am trying to use a combination of r.walk and r.drain in the QGIS grass plugin to model the most efficient path between two points, where cost is accumulated principally by movement over deeper ...
0
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1answer
190 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 ...
1
vote
1answer
72 views

Calculating percentage of cells which are lower than site in Grass GIS?

In GRASS GIS: I have a shapefile with 300 hundred of sites (with height values for each point), and want to calculate the percentage or number of cells (of a given DEM) which are lower than the ...
1
vote
1answer
52 views

cells w/in search window GRASS GIS

I am trying to find all cells that are a certain distance and within a certain window from a cell of interest. For example: I want all cells in a distance of 10m within a search window of 10 - 40 ...
3
votes
2answers
57 views

Making a simple line- complex

I am trying to make my own version of code to generate elevation profile for a line drawn over a DEM and I got stuck very early on. As a simple use case: I have a line that consists of just two ...
4
votes
0answers
77 views

Speed optimization of shadow computation with grass gis r.sun

I am trying to optimize the speed of r.sun to compute shadowed area on a DTM at 1m resolution. My current area is 3.39 km² but my final area will be 450 km². The r.sun wiki say that pre-computing ...
3
votes
1answer
135 views

Cannot open r.viewshed on Grass 7

I cannot open the r.viewshed tool in Grass 7.0.3. I am using the 64-bit version on Windows 7. The error message is given below: Traceback (most recent call last): File ...
3
votes
0answers
56 views

r.sun from QGIS toolbox doesn't give realistic value about the hours of insolation

I have a problem with the GRASS module r.sun when I run it in QGIS. I would calculate the hours of insolation in a specific site during a specific day. When I ran the algorithm "r.sun" from GRASS, it ...
1
vote
1answer
57 views

Sunshine hours duration calclulated from r.sun (GRASS Plug in) are same for diffrent date

Currently i am trying to calculate sunshine hours duration from r.sun (GRASS Plug in ) from QGIS 2.12. I want to calculate sunshine duration for 21 st jun and 21st December for same elevation data ...
2
votes
1answer
29 views

QGIS graphical modeler: how to automatically enter parameters in r.drain.coordinate tool

i am carrying out a cost least path analysis and i am using QGIS. The processing tools i am using are: r.cost.full and then r.drain.coordinate Considering i have more than 1000 layer to process ...
1
vote
2answers
106 views

GRASS init error in QGIS?

Every time when I start my QGIS I see the following message: GRASS init error: Problem in GRASS initialization, GRASS provider and plugin will not work : Module built against version $Revision: ...
2
votes
3answers
27 views

Grass 6.4.3 v.rast.stats: Calculate only one value

I am using the grass (6.4.3!) function v.rast.stats to calculate the mean value of rast values over polygons. The tool is somewhat slow and I actually only need the mean value. Is there any ...
5
votes
1answer
297 views

Grass NVIZ has no output in QGIS 2.8.1 ubuntu 14.04

I am trying to use the Grass7 NVIZ algorithm from the QGIS 2.8.1 toolbox, on ubuntu 14.04. I have enabled Grass7 in the QGIS processing preferences. I have compiled Grass7 from source, and Grass ...
1
vote
0answers
47 views

Python error when using r.reclass on raster with no CRS

I have a set of GRID data (directory of .adf files) that I'm trying to reclassify in QGIS. I'm using the GRASS r.reclass function to try to reclassify the layers, but GRASS keeps failing and ...
0
votes
0answers
9 views

Can grass 7.0.3 pansharpen Landsat 8 spectral bands [duplicate]

Can grass 7.0.3 now pansharpen Landsat 8 rgb spectral bands. The last post in 2013 said that a programmer was working on it.
4
votes
1answer
157 views

basin creation GRASS vs. flow direction

I have a strange behaviour in QGIS with GRASS tools. I am trying to create basins in the alp region and use he SRTM3 data. As I can see on the flow direction raster the SRTM3 data seems to act nice: ...
1
vote
0answers
22 views

QGIS and GRASS 7 integration [duplicate]

I want to integrate QGIS 2.12.3 or 2.13 with GRASS 7, but I still haven't been able to do so. Can someone please tell me how can I do this with a stable QGIS version.
0
votes
1answer
67 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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0answers
27 views

My OSM country roads network is not routable [duplicate]

I need a routable shapefile in order to execute pgrouting algorithms. I download a national zip from http://download.geofabrik.de/europe/greece-latest.shp.zip and import the roads shapefile in my ...
3
votes
1answer
688 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? ...
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0answers
37 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 ...
5
votes
2answers
2k 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
97 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
75 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 ...
2
votes
1answer
31 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
71 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
270 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 ...
3
votes
0answers
39 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 ...
6
votes
3answers
694 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
vote
0answers
39 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
778 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
64 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
61 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
155 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 ...
32
votes
4answers
811 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
51 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
321 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
108 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
45 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 ...
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0answers
84 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
513 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
125 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 : ...