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
2answers
28 views

What logical function should i use to do a union of two raster files in GRASS?

The files are : DEM and roads. For the following i did euclid distance and then reclass. Now i need to know with what logical function to combine them elevation rank ...
1
vote
1answer
269 views

How to activate GRASS GIS 7 plugin in QGIS 2.8?

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
0answers
44 views

Problem in running r.sim.water

I am trying to run the r.sim.water in GRASS. I have calculated the partial derivatives dx and dy rater map using r.slope.aspect. I am using this elevation map [1] to get the time-series depth map. But ...
0
votes
0answers
17 views

GRASS watershed analysis add storm inlets

Try searching for this with no luck. I am using r.watershed to delineate flow directions, subwatersheds, etc. All good, except that storm drain inlets, culverts and subsurface drainage courses are ...
3
votes
0answers
50 views

Steiner tree problem: Optimal routes for Fibre planning on road network

I am trying to solve a large optimization problem where I have a set of nodes on a road network that need to be connected using fibre using the shortest possible amount of fibre. The problem is a ...
2
votes
1answer
52 views

How to add my own GRASS algorithms to Processing?

I need to use algorithm r.bioclimatic from GRASS in QGIS but I see that this algorithm don't exist in Processing Toolbox. A search a way of add this algorithm to Processing and in GRASS and Sextante ...
0
votes
3answers
49 views

GRASS convert raster to points

I have tried to convert a raster to points using this syntax: r.to.vect input=g_kelowna_merged@kelowna_mapset output=g_kelowna_points feature=point I have tried using the GRASS interface in QGIS and ...
1
vote
0answers
39 views

Why is QGIS 2.8.1 crashing when enabling Grass Plugin?

I am running Linux Mint 13 "Maya" (Ubuntu 12.04 Precise). I installed Grass via the software center. Than I installed Qgis 2.81 following this procedure: Add the lines for one of the repositories to ...
0
votes
2answers
91 views

How can I extract a smooth river network with QGIS & GRASS?

I´m working with Qgis 2.6.1 and GRASS. I have used the r.watershed module to create a flow accumulation map. With r.mapcalc I have extracted the river network, then i´m using r.thin to thin out to a ...
1
vote
0answers
25 views

Change GRASS module default parameter

I´m new to Qgis and GRASS. I need to change the default parameter skip of the module r.to.vect.lines, from its default value of 10 to 1.How can I do this? r.to.vect.lines [-v] input=name output=name ...
0
votes
0answers
11 views

Default horizonstep in r.sun

I am working on software suite to create some geoscience models on Digital Elevation Models. Part of the process is to calculate the Insolation Time and Global Irradiance using r.sun. We are running ...
1
vote
0answers
57 views

Simulate water runoff to get water height over each pixel of DEM

Here is my problem that I am trying to deal with. I have given a height map of around 512X512 resolution(It is Geo-referenced and I have the meta-data for this). And I have given that this area ...
1
vote
1answer
46 views

GRASS Zero-Crossing Edge Detection

I have a classification of vegetation communities across a landscape in a .tif format. I wanted to use the GRASS Zero-Crossing Edge Detection tool in QGIS to help define boundaries between my ...
5
votes
0answers
141 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 ...
2
votes
0answers
78 views

How to create line segments between pairs of pixels in a raster?

I want to draw several lines between pixels (please see the image below) according to some criteria : First Criterion: The distance between 2 pixels is less than 2000m and greater than 500m ...
0
votes
1answer
13 views

Move Landsat 7 Image in Grass 7

I got 2 landsat 7 images from the same place but different date of adquisition, image A is well placed, but image B is shifted about 1500 meters east and 14700 meters north. I need to use both images ...
0
votes
0answers
69 views

How to reference a number variable in r.mapcalc within QGIS graphical modeler

I need to run the following formula in r.mapcalc: (xor(abs(A-B),abs(A-C))>120)*A I would like to however use a user defined number input variable instead of the 120. I already have this variable ...
1
vote
0answers
20 views

Second order rectification display problems

I'm using GRASS 7.0 to geo-rectify oblique images taken from a fixed altitude and using RTK-GPS data as a GCP (as a vector file) for the process. The survey area is very small and flat, so I'm not ...
2
votes
2answers
33 views

How to combine the content of several mapsets into one new mapset in GRASS.?

I have some mapsets and i want to assemble them into one new mapset and have everything into it. How do i do it?
4
votes
2answers
575 views

Is it possible to use GRASS GIS in Python stand alone scripts?

I am trying to find a least cost path script for Python. I came across r.drain from GRASS GIS. Is it possible to use GRASS GIS in a Python stand alone script? If so where can I download the bindings?
1
vote
1answer
28 views

Grass r.out.gdal, wrong values when importing to QGis

I have a problem with export/import functionalities between Grass and QGis. I create a raster file in Grass (with r.wind.sun, but that most likely does not matter) It has the following properties: ...
1
vote
1answer
34 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 ...
5
votes
2answers
453 views

Creating contours for specific elevations

Input data: 1. an SRTM raster. 2. Point file of peaks. -Attributes contain ID, x, y, z and the elevation at which the peak is completely isolated from a neighboring peak. The output I want is a ...
0
votes
0answers
58 views

How to process a big number of raster outputs with r.series?

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) ...
0
votes
0answers
18 views

Calculating Odd and Even side of road using PyQGIS and GRASS

I'm trying to programmatically and automatically assign odd and even sides of a road to number homes using QGIS and GRASS. I noticed this other post, which gives a solution using PostGIS and I have ...
0
votes
0answers
61 views

Least cost path analysis : a lot of sources and destinations

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. I ...
0
votes
1answer
38 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
76 views

Preprocessing GeoEye-1 in GRASS iatcorr

I am trying to do a study on land use change using three high-res images of an area from three sources (Quickbird, GeoEye-1, WV-3). I have managed to calibrate the Quickbird data using QGIS raster ...
14
votes
4answers
2k 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
511 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
20 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, ...
1
vote
0answers
190 views

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

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
51 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
139 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
50 views

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

I use mac and when I try to use grass modules in qgis (brighton) I get a "cannot find module" message.
1
vote
1answer
150 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
56 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
7k 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 ...
0
votes
0answers
49 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
36 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
29 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
578 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
28 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
31 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
18 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
119 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
61 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
60 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
71 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 ...
1
vote
2answers
137 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 ...