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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Failing to import lidar data in Grass 7 [on hold]

I've installed liblas 1.8.0 and python setup.py inside of liblas installation folder. When trying to import lidar data in Grass 7, I get the following error message: Traceback (most recent call ...
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1answer
12 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?
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13 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 ...
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23 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 ...
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24 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 ...
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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, ...
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39 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) ...
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1answer
31 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.
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34 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 ...
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16 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 ...
0
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1answer
12 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 ...
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26 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 ...
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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.
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14 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 ...
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17 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 ...
2
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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
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3answers
32 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 ...
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27 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, ...
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2answers
71 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 ...
2
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38 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 ...
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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 ...
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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" ...
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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 ...
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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
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1answer
29 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 ...
2
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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 ...
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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. ...
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2answers
55 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 ...
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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 ...
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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 ...
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1answer
30 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 ...
1
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1answer
47 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 ...
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37 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] - ...
8
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2answers
264 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 ...
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0answers
10 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 ...
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0answers
43 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') ...
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1answer
21 views

Adding GeoEye1 sensor to grass i.atcorr

Following the instructions, I've updated the iwave.h and iwave.cpp files using the official spectral responses from DigitalGlobe (In the iwave.h file I don't know if it's necessary to use more ...
2
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0answers
24 views

Error using grass script v.lidar.edgedetection

I'm in trouble with the grass script v.lidar.edgedetection. When I try to filter an xyz format dsm the script starts but at the end of it an error message appears (see attached image). Somebody ...
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19 views

solar radiation r.sun

I have a dsm and dem for an area. When I try to run r.sun module to calculate solar radiation I receive this error message in the picture. This problem does not occour when I don input slope and ...
2
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3answers
57 views

How to export a GTiff with its GDAL colour table, in GRASS, which is suitable for Adobe Illustrator?

I've created a new raster in GRASS, starting from a dem and using the commands r.relief and r.shade. Now I would like to export this new raster as a georeferenced image and import it in Adobe ...
0
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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 ...
3
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1answer
90 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 ...
2
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0answers
87 views

How to build a GRASS network with node IDs from the line dataset?

I have a dataset of street network links (line geometries). Each network link has a link id, start node id, and end node id attribute. I want to use this network in GRASS, so after importing the ...
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27 views

Command Grass in QGIS not work

When I use r.contour or other Grass commands in QGis, I have this error message. Why?
1
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1answer
20 views

hdf-eos5 file format import in grass

I want to import AURA-OMI ozone level3 data which is available from http://giovanni.gsfc.nasa.gov/giovanni/ .The data is in hdf5 format. The extension is .he5. Do anyone know how to import in grass. ...
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33 views

What's the best neighborhood size to smooth the ASTER GDEM v2, resampled at 1m res, in GRASS with r.neighbors?

Basing on your experience, what neighborhood size could be a good compromise to smooth the ASTER GDEM v2, resampled at 1m res, without affecting too much the edges and the valleys? I have to realize ...
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1answer
52 views

What's the right way to calculate the scale parameter value for r.relief in GRASS?

I have a little doubt about the way I should calculate the value of the "scale" parameter in the r.relief command in GRASS. In the description section of the r.relief page of the GRASS manual I read: ...
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0answers
52 views

GRASS GIS r.walk issue

I have been playing around with GRASS GIS to do a simple cost analysis of getting from point A to point B. I have a DEM clipped to the study area, a raster containing the friction costs, as well as ...
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27 views

How to smooth a shaded relief map created with the command r.relief in GRASS 7?

How can I smooth a shaded relief map created with the command r.relief in GRASS 7? I read about the plugin r.denoise but I can only find it for GRASS 6... Thanks in advance. Bryan
2
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72 views

Performance difference between focal statistics (ArcGIS) and neighbor (GRAS or QGIS)

I tested minimum, maximum, and average neighbor (circle radius = 161 pixel) using ArcGIS, GRASS and QGIS: ArcGIS (10.1): it takes only one minute GRASS (6.4.3): it takes 123 minutes for every output ...