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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4
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1answer
87 views

GRASS 6.4 Reinstallation for Ubuntu

I need to reinstall GRASS 6.4 on this Ubuntu computer due to compatibility issues. I had installed GRASS 6.4 a few weeks ago to work with a simulation program. I used the command apt-get install ...
2
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0answers
36 views

C/C++ function to return minimum set of points required to represent a geometric shape

I am looking for a method from Grass, GEOS, or similar that will delete those points in a geometry which do not affect its shape. Example 1 +----+----+ p0 p1 p2 p1 can be deleted without ...
4
votes
1answer
79 views

Why can't I see v.net in QGIS GRASS tools

I have noticed answers such as Is there an open source tool to planarize graphs? stating you can use GRASS v.net from within QGIS. However I can't see it - my QGIS processing GRASS toolbox contains ...
32
votes
4answers
723 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 ...
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 ...
3
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2answers
233 views

Least cost path between various points QGIS

Is there an easy way to find the least cost path (LCP) between various points in an open source GIS? This question has actually already been asked here: How to find a least cost path through several ...
1
vote
1answer
22 views

What projections and input file parameters are supported by r.resamp.rst?

I always get ERROR: Unable To Seek after I run r.resamp.rst r.resamp.rst input=map30 ew_res=10m ns_res=10m elevation=map10 It actually starts to work but after it finish I get the error and no ...
3
votes
2answers
458 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
2answers
93 views

Grass GIS: Number of CPU cores to use

E.g. in SAGA GIS it is possible to set with one click the number of CPU cores to use during processing. Is this also possible in Grass GIS?
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0answers
43 views

Issues related to lack of Landsat 8 Metadata usage in i.landsat.toar run [duplicate]

In my application of i.landsat.toar, I am coming across an issue for which there is previous precedence. LANDSAT 8 i.landsat.toar error GRASS 7 Computer Basics: Data Used: Landsat 8; Operating ...
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0answers
34 views

How to determine Grass (i.atcorr) tool control file's “visibility for the aerosol model [km]” value

In Grass, the Atmospheric Correction tool (i.atcorr) reference do not provide information with regards to the parameter "visibility for the aerosol model [km]"stated in the control file.I have ...
1
vote
1answer
48 views

Regarding Atmospheric correction and Elevation DEM Projection system

I am trying to conduct atmospheric adjustment of Landsat 8 image bands using 6s algorithm (i. atcorr grass gis tool). It seems, in the input section, an elevation raster map should be provided. In my ...
2
votes
2answers
120 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 ...
2
votes
1answer
36 views

Why there is no “View Output” button for the command “v.to.points” in Grass plugin in QGIS?

How do i get or where do i get my output vector point layer after i run the command v.to.points to my vector line layer?
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vote
2answers
36 views

Resetting 'cat' column in GRASS?

I've got a regular polygon file that looks like this: Unfortunately, this file stems from a v.overlay so that the 'cat' values are are a bit messed up. I would like them e.g. to start in the upper ...
2
votes
1answer
39 views

Matching raster regional extent with vector region in GRASS?

In Grass GIS, I am able to import bathymetry .tif raster data however the region coordinates are not in lat/lon formar and therefore, do not overlay with my vector points which are in lat/lon format. ...
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 ...
0
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0answers
36 views

GRASS: Site Analysis using address lists in vector maps

My objective is to analyze and optimize the distribution of sites (e.g. shops) in a certain area.In the end I want to be able to answer questions such as: How much farther or less will customers ...
1
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0answers
31 views

Extracting distances along a line from postcode a centroid to the nearest point (bus stop)

I'm looking to measure the distance from postcode centroids (point file) in a city to the nearest bus stop (point file) along the road network (line file). In Qgis I can calculate the distance but ...
6
votes
2answers
228 views

Skeletonize vectors in QGIS/Python

I am trying to find a tool to create a skeleton of a large vector dataset using QGIS and its bundle. It should be directly programmatically callable through Python or commandline (QGIS, GRASS, OGR ...
1
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0answers
47 views

GRASS GIS i.landsat.toar hangs & holds CPU at 100%

I use python scripting to automate processing of several Landsat 8 scenes. I use a VPS (4 core, 8GB memory, SSD) running Ubuntu 14.04 with GRASS 7.0.1 Line in script for i.landsat.toar: ...
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0answers
26 views

Best way to store, elaborate and query raster data [closed]

I have created multiple raster images with GRASS-GIS (~150Gb), that I'll need to multiply for a certain coefficient, and query the results that need to by saved just temporally. The portions of the ...
1
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0answers
45 views

G_Malloc error for Grass module(r.stream.extract) in R

I am having a big issue of this G_malloc Error while using a module of Grass (6.4.4) (r.stream.extract) in R. Initially I thought my computers configuration was low, So I switched to 8gb Ram 64-bit ...
1
vote
2answers
124 views

Tool or program to clean polygon dataset

I have a polygon dataset (shapefile, mapinfo tab file) which I would like to "clean" to be topologically correct. The polygons are assigned an ID which represents a specific class. For example ID 3 is ...
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0answers
28 views

Raster statistics change after re-projection — which one is correct

I'm looking into some global DEMs (like ETOPO1 - http://www.ngdc.noaa.gov/mgg/global/global.html), and noticed that the statistics for the elevation values can change quite a bit after reprojecting ...
2
votes
0answers
33 views

QGIS - WHERE SQL within a processing.runalg statement for v.surf.rst in python console

I'm creating lots of raster files with grass:v.surf.rst so rather than using the graphical interface I wanted to use the python console (and potentially put in in a script at some point). However ...
2
votes
1answer
118 views

Atmospheric Correction Model Output for Landsat 8 Image?

Following are my procedure, observation and question/ request: Data Source: Earth Explorer Landsat 8 Grass GIS Version: 7.0.2 RC1 Windows 7 32 bit OS I have been trying to conduct an Atmospheric ...
0
votes
0answers
21 views

TIF file is black in GRASS when imported

I'm trying to input a TIF file into GRASS. Dimensions: 11617 x 15489 Size: 514 mb Color Palette: 2 colors (black background, white polygons). Layers: one layer Compression: none Software used for ...
2
votes
2answers
89 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. ...
0
votes
1answer
87 views

Determination of Soil Moisture for a Region Using open Source Data

I want to derive soil Moisture for a region using Landsat and Microwave data could you please help me with the procedure.
3
votes
1answer
119 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 ...
2
votes
2answers
103 views

Points that get created in the wrong order when using e.g. QChainage?

I have a polyline layer (road) that I want to use to get a point layer with 1 km between the points. I have tried both 'QChainage' and 'Locate points along lines' to do this. They both work, I get ...
1
vote
1answer
63 views

Reading files from grass into R with loop

I have a connection between GrassGIS and R. I want to read thousands files from my mapset into R. I have lines with names "line1","line2"... I know I have to use a loop for this so I did ...
1
vote
1answer
360 views

How do I install qgis lyon with grass access

I am working wit a win10 64 bits 16mb of ram. I want to install Lyon on my computer and not get rid of 2.83. My 2.83 is a stand allone install. I thought I could install Lyon usion OSGEO 4w installer. ...
1
vote
0answers
39 views

How to determine aerosol model value for i.atcorr in GRASS? (Using Aeronet data)

I am trying to conduct atmospheric correction of landsat 8 image using i.atcorr of Grass GIS. In thıs regard, I need to know Aerosol Optical Depth (AOD) as stated in Grass wiki page. I've found some ...
2
votes
3answers
82 views

Storing large number of mapsets with many raster maps

OS X El Capitan, GRASS GIS 7.0.1 I have a location with about 530 read-only mapsets with each about 2600 raster maps (plus PERMANENT and one link to a read-write mapset), overall 11.255.481 raster ...
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
41 views

GRASS PyWPS Create a new vector map from user selected polygon

My goal is to select a specific polygon in which the user clicked and make a new vector map that contains only the selected polygon. I see two ways: Convert XY coordinate from literal input to a ...
2
votes
1answer
70 views

Reproducing GRASS GIS network analysis tutorial in QGIS Field Calculator

Im looking to reproduce the assigning of road speeds as denoted in a GRASS GIS tutorial (v.net.alloc tutorial), where the road speed is assigned by road type (i.e. 'interstate' = 75 mph etc.) to then ...
3
votes
1answer
90 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 ...
1
vote
1answer
93 views

r.cost multiple destinations

I am trying to calculate the optimal route from one archaeological site to multiple sites. I already have the r.cost raster. My question is if I can use r.drain to multiple destination points.
1
vote
2answers
72 views

Addon installation problem on GrassGIS

I am facing a problem with GrassGis 7.0.1. I want to install r.viewshed.cva form Addons. I don't get an error during installation but when I try to open the plugin I get the error : ScriptError ...
1
vote
1answer
194 views

QGIS 2.10.1. GRASS Algorithm Processing

While selecting the GRASS algorithms 'Processing algorithm: v.to.points - Create points along input lines' The error message came up: The specified GRASS GIS 7 folder does not contain a valid ...
2
votes
1answer
60 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: ...
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0answers
37 views

For preparing watershed delineation with QGIS Grass module I couldn't find r.watershed module

For preparing watershed delineation here some one has described some steps as follows After step 2, I want to get flow accumulation file, but I can not find this kind of module in GRASS, so I pass ...
2
votes
1answer
94 views

How to brew GRASS with Postgresql support? [closed]

On my Mac, running OS X 10.10.5 and I installed Grass with homebrew: brew tap osgeo/osgeo4mac brew install grass-70 Unfortunately, I cannot choose the pg driver in the db.login menu. Can anyone ...
0
votes
0answers
771 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 ...
1
vote
1answer
250 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 ...
1
vote
2answers
55 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 ...
0
votes
0answers
57 views

GRASS: launch <wxpython> GUI fails to launch after selecting mapset

I built grass70 from source on Ubuntu 14.04 desktop using the documentation at the Grass Wiki. I can initialize grass70 from the command line, and the startup GUI appears to select my project / ...