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.

learn more… | top users | synonyms

0
votes
0answers
3 views

Least cost paths : multiple start points and multiple possible end points

I'm working on a 15*10 km area, splatted in a 50*50 m cell grid. I want to compute the time needed to travel from a single starting point to each cell centroid, combining driving and walking time. ...
0
votes
0answers
19 views

How to process a big number of raster outputs?

I am new to python and QGIS. I'm trying to take some simple operations (e.g. count, average) over a big number of raster maps from a python script. I'm using the "r.series" algorithm (from processing) ...
14
votes
4answers
1k views

Rubber sheeting in GRASS or QGIS

We are in the process of getting our property boundaries corrected and a side effect of this is that we need to move any assets that have been drawn relative to the property boundaries, so they are ...
1
vote
1answer
409 views

Can't launch GRASS GIS 6.4.3 GUI on windows 8.1

As title, I downloaded GRASS GIS from this website: GRASS GIS - Home, and I choose winGRASS 6.4.3 standalone installer to download. After I installed, I click on its icon: I can't launch it even ...
0
votes
0answers
14 views

Why do GRASS' NC dataset and USGS' CONUS dataset coordinates disagree?

In the course of trying to figure out a specific data extraction task, I'm trying to understand the coordinate system used by GRASS. For a while, I'd been working with elevation data near Raleigh, NC, ...
0
votes
0answers
9 views

GRASS make local relief error

While using/trying to make a local relief in GRASS with the plugin r.local.relief i stumble across a error. ERROR: G_realloc: unable to allocate 15000000 bytes of memory at ...
1
vote
0answers
170 views

where to perform principal components analysis and tasseled cap transformation [on hold]

I want to perform a principal components analysis (pca) and a tasseled cap transformation (tasscap) for a classification.Should i perform pca and tasscap on the original bands of my image or on the ...
0
votes
0answers
50 views

Time processing in GRASS?

I am computing NDVI for Landsat TM in grass 6.4.3 in raster map calculator, and time processing is many hours and finally tke message is "failed". trying to find a solution I discovered that it ...
1
vote
1answer
76 views

Export of group = multiband raster to another format not works in GRASS

I am really new in GRASS and my question is really basic but I dont realize where I am wrong. I have a set of single layers in my PERMANENT from some Landsat images (1 landsat = 7 one layer ...
0
votes
1answer
23 views

How to find the path after “cannot find module” message when I try to use grass tools in qgis [on hold]

I use mac and when I try to use grass modules in qgis (brighton) I get a "cannot find module" message.
0
votes
1answer
193 views

Grass 7 on Ubuntu 14.04. Can't start Grass

I attempted to install GRASS GIS 7 on ubuntu 14.04 using these instructions. When I call grass70 from the command line I get a welcome message and a prompt to continue. I then get two error messages: ...
0
votes
0answers
31 views

Activating GRASS GIS in QGIS

Apparently, my linux ubuntu setup of QGIS doesn't contain grass gis, although when I initially installed it last week I added grass gis to the command line. Anyway, I typed in once again and installed ...
0
votes
1answer
132 views

GRASS i.landsat.toar returns empty raster

I am trying to use the GRASS module i.landsat.toar. Currently the files created are empty and it spits out: So it seems that it is not picking up something? The location is set to the extent of ...
1
vote
1answer
130 views

How do I install mdenoise in GRASS?

How do I install mdenoise in GRASS 6.4.3? I've already successfully installed r.denoise, and have downloaded mdenoise from wget http://www.cs.cf.ac.uk/meshfiltering/index_files/Doc/mdsource.zip. How ...
0
votes
0answers
10 views

GRASS GIS : ScriptError : Unable to fetch interface description for command 'd.rast'

I'm new to GRASS GIS (6.4.3) and I'm trying to use the r.watershed command. I imported the GTOPO30 DEM in tiff format, but I can't display it. I get the following Script Error: "Unable to fetch ...
25
votes
4answers
6k 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 ...
1
vote
1answer
236 views

How to interact with GRASS GIS vector map topology “level/layers” from terminal/command line?

Is there anybody out there that can maybe assist in the most simplest form of code to call on command line to "export topology" (which is level 2 information in GRASS) as separate spatial data, as ...
0
votes
0answers
25 views

How to merge two rasters when are on the same place

I have two rasters in GRASS GIS. first : raster of DMR, raster picture of relief - created from high values second : raster of buildings where pixels of every building have value of high of this ...
0
votes
0answers
31 views

I have an error when I execute a command in grass raplat

I use grass 6 in ubundu. I have putted the date into the .csv file and the antennas in .msi format, but when I try to execute the command in terminal "r.radcov" the system show me an error as: Error ...
0
votes
0answers
17 views

Grass functions (for example, r.li) on QGIS Processing Toolbox

I need to know if it is possible to add other functions, such as r.li to Processing Toolbox. Thanks.
3
votes
2answers
502 views

How do I reproject one raster to match another's in GRASS

I have two raster layers, A and B, which have information about the same location but have different projections and datums. How can I reproject layer A to match the projection and datum of layer B? ...
0
votes
0answers
12 views

Is this error “invalid context…fatal error” due to GRASS GIS bug or the system?

Copy of error message that appears in the terminal (Macbook Pro, OS X 10.9.5): MacBook-Pro.local Python[2653] :CGContextRestoreGState: invalid context 0x0. This is a serious error. This ...
0
votes
0answers
15 views

Is there any way to add the Origin ID in the isolines calculations (GRASS GIS)?

I would like to ask whether there is anyway in to add the OriginID in the calculations of the Isolines (v.net.iso) in GRASS Gis. The calculations are a bit useless if they only include the cost ...
0
votes
1answer
13 views

What causes v.net connect “Failed to find intersection segment” and how to fix it?

In GRASS 7, when running v.net connect, I get the ERROR: Failed to find intersection segment and no output is generated. The only mention of this error Google found is in the source of connect.c What ...
2
votes
3answers
28 views

How to create custom color ramp using “r.colors” GRASS GIS function?

I am trying to assign a raster/grid a custom color palette in GRASS using the "r.colors" function. r.colors map=Consensus_BRT_RCP85 colors=rules This allows me to input my rules for my color ...
2
votes
1answer
60 views

Trying to extract arc information from a Suburb shapefile

I downloaded some shapefiles from the Australian Bureau of Statistics (ABS). It's basically showing a bunch of suburbs when I view the shapefile through a GIS tool. The GIS tool that I am using at ...
1
vote
1answer
48 views

Error in executing commands in GRASS GIS

I'm using Grass 6.4.3RC2. I have a problem because when I execute the command: r.radcov csv_file=cell_list_hataDEM_umts_amc_testTEST.csv dem_map-AlbSRTMdem@PERMANENT clutter_map=AlbClut@PERMANENT ...
2
votes
1answer
41 views

How to get mean geographic direction of a polygon in QGIS?

I have a raster height model and would like to calculate the horizontal geographic direction (north, east, etc. - orientation) of each cell, then calculate then the mean value of all these cells in ...
2
votes
1answer
760 views

Create a 3D surface from xyz csv using GRASS

Apologies if this is a repeat question guys. I am trying to create a 3D bathymetry surface from xyz data. There is approximately 300,000 points with lat, long and z (depth data). The data is sonar ...
1
vote
2answers
68 views

Shortest Path Matrix with QGIS/GRASS

I signed up just a minute ago, because I am working on my Master's thesis and could not find a working solution for the following problem: I am analyzing Germany's high voltage electricity grid. I ...
0
votes
2answers
54 views

DEM with bathymetric contour lines in GRASS

I am trying to create a DEM from a bathymetric contour lines. Contours are in vector format and the elevation value is negative. To create the surface I have converted the contours in raster (v.to ...
0
votes
1answer
43 views

Import BigTiff files in Grass

I am trying to import a raster (geotiff) in Grass with size of 64 GB . It makes me an error like this: ERROR 4: This is a BigTIFF file. BigTIFF is not supported by this version of GDAL and libtiff. ...
1
vote
3answers
142 views

How to calculate mean aspect in circular statistics?

Measurements of angles (e.g. compass bearings, aspect) are circular in nature (e.g. 0 and 360 degrees coincide) and therefore cannot be meaningfully described by ordinary arithmetic means. I have a ...
0
votes
0answers
25 views

Is it possible to use d.nviz in QGIS 2.8.2?

I read that this algorithm belongs to GRASS 7 only but GRASS 7 doesn't work in QGIS (Missing dependencies). How do I do that? By the way I want a raster animation with time. And d.nviz can help with, ...
2
votes
0answers
37 views

Calculate cover loss between years using r.mapcalc

I am working on forest cover raster data for 2 years and am interested in areas with >5% loss in forest cover. I am pretty new in GRASS GIS, so any suggestions for how to create a difference map of ...
1
vote
0answers
54 views

Sophisticated generation and calculation of Vector entities from Raster Data?

The first image below is shown a raster wish represents the altitude value. I created this raster by applying this process, bu using this process we can manually select an upper and lower area (so 2 ...
2
votes
3answers
651 views

Converting Landsat8 DN to TOA reflectance for use in envi

I am used to working in envi, however my current version does not support Landsat8. I downloaded GRASS for the express purpose of converting Landsat8 DN to TOA reflectance for use/analysis in envi. ...
0
votes
0answers
15 views

Losing polygons when importing shapefile in GRASS

I have a complicated mapinfo .tab file of wildland urban interface zones. They are represented as polygons. I am importing into GRASS using the following command: v.in.ogr -c dsn="C:....path" ...
1
vote
0answers
26 views

Extracting area from DEM Raster?

After applying constraints to the DEM I polygonised the raster (using GRASS r.to.vect.area) The result is shown below with a lot of vector with resolution = [30 * 30] Is there any solution to make ...
1
vote
1answer
28 views

Projection change in QGIS after import & export in Grass

I'm working on an application written with Grass command in python and I have a projection problem. First I create a location with belgian lambert 72 (EPSG:31370) in Grass 7.0. After importing all ...
1
vote
1answer
21 views

Duplicated vertices in contour features of GRASS?

I use GRASS to produce contours from DEM (r.contours for SRTM rasters). They looks fine, but most of the line features occures to be duplicated; i.e. verticies duplicated. Here are pictures of output ...
2
votes
0answers
23 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 ...
1
vote
1answer
54 views

How to have newly added lines split existing lines where they intersect, using QGIS

I have a line shapefile where the lines form a closed polygon. Using QGIS (2.8 on OSX 10.7) I would like to add lines to the layer, basically splitting the polygon into quadrants. Then, I will need ...
1
vote
1answer
29 views

Looping inside r.mapcalc in GRASS GIS

I have a Land Cover classification map that I created from 2m resolution multispectral imagery and I am trying to downsample the results to a 20m resolution class map. The climate in question is ...
8
votes
2answers
263 views

Migrating from ArcGIS to gdal

I would like to collect a table of equivalent or close enough gdal based functions to replace ArcGIS functions (esp in spatial analyst). Are there functions available using gdal to perform the ...
1
vote
1answer
46 views

How to create shadows of buildings with r.sunmask?

I need to create image-raster with shadow of relief and shadow of buildings in one. I know how to create shadow of relief but how i can create shadow of buildings with r.sunmask? I dont know how from ...
2
votes
2answers
226 views

Issue while running grass from subprocess

I have a map based web application using geodjango. I needed to display the crime hotspots within a selected polygon area. I found that v.kernel is very good for generating heatmaps/hotspots. So in my ...
1
vote
0answers
36 views

GRASS GIS r.slope.aspect write errors

I am running into an error running r.slope.aspect I have never seen before. When I run it, I get the following output: r.in.gdal complete. Raster map <dem> created. WARNING: map [slope] - ...
0
votes
1answer
192 views

Problem opening GRASS GUI: libgeos-3.3.6.so: cannot open shared object file:

I have been using GRASS to process some Landsat imagery but very recently, and as far as I am aware - after having done nothing different or changing the settings, I am trying to use GRASS and on ...
1
vote
0answers
42 views

How to use d.* from a python/bash script in GRASS GIS 7.0?

Do d.* commands from GRASS GIS 7.0 run from a python script? I'm trying with this code: import grass.script as grass grass.run_command('d.mon', start="wx3", resolution = '1') ...