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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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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27 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 ...
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32 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 ...
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131 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
47 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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66 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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64 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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33 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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38 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 ...
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1answer
51 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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46 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] - ...
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270 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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1answer
12 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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50 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
25 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 ...
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25 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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20 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 ...
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3answers
78 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 ...
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17 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 ...
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1answer
115 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 ...
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100 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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30 views

Command Grass in QGIS not work

When I use r.contour or other Grass commands in QGis, I have this error message. Why?
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21 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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35 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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61 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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61 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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28 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
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86 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 ...
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17 views

Reading L1B ASTER in GRASS using r.in.aster

I'm having a problem getting an ASTER L1B to be read in GRASS using r.in.aster. The output the command shows this: (Wed Apr 8 17:49:03 2015) Command finished (1 sec) (Wed Apr 8 17:49:37 2015) ...
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1answer
37 views

Generate a raster with a uniform value using QGis

I'm working on a project using the qgis-modeler and i want generate a raster with a uniform value. i'm using r.surf.random function of GRASS which need min and max value but i want have only one ...
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86 views

Grass Processing tools via QGIS : v.clean snap, chdangle, and rmdangle

Using QGIS 2.6 Grass Processing tools, I'm trying to clean up topology on a water network layer. I noticed topological errors when first trying to break all lines on intersections using v.clean break. ...
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2answers
84 views

Ls factor, flow accumulation, watershade, relief in Quantum GIS 2.2

I'm a beginner quantum gis. I want to make the LS factor of 30m DEM that I have merge and set the projection in wgs 84/UTM zone 49S (EPSG ; 37249). I'm having a problem when trying to create relief ...
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18 views

Is there a max number of cells which r.surf.contour can interpolate in GRASS?

Nothing less, nothing more... I'm wondering if there's a max number of cells which r.surf.contour can interpolate in GRASS, because I have to interpolate a region of 24000 rows x 23000 columns but I ...
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86 views

Unable to start modules in QGIS GRASS plugin (GNU/Linux Debian)

Recently, the Toolbox of QGIS GRASS plugin can't find modules in my GNU/Linux Debian. When I click on any module, the toolbox reports the message: Cannot find module x.xxx and, after, I have the ...
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1answer
57 views

Old question without answer: R.Neighbors with large neighborhoods?

I'm working on the same theme as User 32882, and I'm new here. I have the same problem, and update his question with more details. Old question: "I'm running into problems running the r.neighbors ...
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1answer
75 views

Conditional calculation - QGIS Raster Calculator or GRASS r.mapcalculator

Is it possible in QGIS either directly or via plugins to do a raster calculation including an if statement? e.g., if raster1 > 0.3, then raster 1 * raster 2, else raster1 x raster3...something like ...
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24 views

wps-grass-bridge misses essential GRASS tool

I set up a Web Processing Service with 52°North and GRASS (using the wps-grass-bridge). I get a similar result like in the online example here: 52°North WPS Demo I assume it would be similar with ...
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17 views

QGIS WPS plugin misses one parameter

I set up a Web Processing Service with 52°North and GRASS (using the wps-grass-bridge). All went smooth and I get a proper DescribeProcess for i.cluster. As you can see, I need to give the parameter ...
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102 views

Pansharpening Landsat 8 tiles in Grass 7

I am trying to get some nice looking RGB images for visualization purposes, mainly using as background maps, from the Landsat 8 archive. I was following the tutorial provided by Markus Neteler at ...
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3answers
31 views

Unexpected result converting a vector to a raster in GRASS 7.0.0

My purpose is to create a DEM raster in GRASS 7.0.0 starting from a shapefile containing contour lines. The attributes table has a field named QUOTE_INT containing the elevation as integer. I ...
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2answers
108 views

Extract Elevation of Points from DEM using Python QGIS or GRASS

I am utterly new to GIS, so please bear with me if I am providing incomplete information here. I have a DEM file (.dt2). What I am looking to do is as follows: take a series of points specified as ...
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1answer
16 views

Where to get GRASS module r3.out.vtk?

I'm looking for the GRASS module r3.out.vtk. It's featured on the GRASS GIS manual : http://grass.osgeo.org/grass64/manuals/r3.out.vtk.html But it's nowhere to be found, and neither are r.out.vtk and ...
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48 views

3d model to point cloud

Excepting FME, is there a way to convert 3d model to point cloud?
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61 views

develop rooftop solar radiation potential from 3d buildings model (3dm)

Need to create solar cadastre without having LIDAR data. Have 3d buildings model in .3dm (150 000+ roof surfaces, 500 000+ facade surfaces unmapped, dtm 15x15m) with a lot of multipatch geometry ...
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1answer
52 views

View feature space for multi-band files

I am trying to plot a feature space (scatter plot) for some SPOT images in QGIS 2.8.1. I know a histogram is available in the file properties, but I want to plot eg. Band 1 vs Band 2 to see the ...
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163 views

How to fix the grass7 package available from the ubuntugis-unstable PPA?

Out of the blue, grass stopped functioning this morning on one of the Ubuntu 14.04 systems I use: $ grass Starting GRASS GIS... python: can't open file '/usr/lib/grass70/gui/wxpython/gis_set.py': ...
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55 views

QGIS, GRASS and WINDOWS 8

Good morning, I'm using QGIS 2.8.1 (Wien) on Windows 8 x64 bit. When I'm trying to lunch the GRASS plugin (6.4.3), Windows shows me the error g.mapset.exe has stop working, then after some times, ...
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1answer
89 views

Removing salt and pepper effect

In a land cover raster (categorical map) that is a product of classified satellite image, what is the best way to remove "salt and pepper" effect from the image after classification. I am not ...
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20 views

Using r.neighbors on borders

I have a raster file with pixel size 30 x 30. At the upper border there is half row with "no data" pixels. I want to use the mode function to replace them. I have only thought r.neighbors (from grass) ...
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31 views

Is it right to remove salt & pepper effect from a product produced by clean images?

I have two images from classification (different years) and I want to find the changes of land cover . I have cleaned the two images (salt and pepper). When I create a cross product of the category ...