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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Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
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2answers
1k views

Is there a Focal Statistics (spatial analyst) tool in ArcGIS equivalent in QGIS?

I'm attempting to use QGIS v2.0.1 to accomplish the same tasks that I can do using ArcMap v10.1 and I'm running into some trouble finding equivalent tools. In ArcMap I am using the Focal Statistics ...
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33 views

Unicode Characters in GRASS ps.map instructions file

I am trying to put text on a ps.map generated map and the text contains the degrees symbol. I can insert the symbol into the instructions file, and it looks fine, but when I generate the map, the ...
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25 views

accuracy of classification in qgis [duplicate]

I have my classified map and my validation points. I performed point sampling with validation points to my classified map. but i am fuzzy with my next step. Some help?
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1answer
383 views

GRASS 6.5 or 7.0 - Need Help with Loop Script

I am new to Python and scripting in general. This is also my first time a posting question. My overall goal is to create a script that I can cycle through all the raster maps in a mapset and then ...
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166 views

Problems with SEXTANTE

maybe the answer is somewhere, but i can't find it right now... I'm getting problems with SEXTANTE and algorithms with GRASS, SAGA... Always is the same, they can't open the files, the error is the ...
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1answer
202 views

Grass GIS and Python Error

I am trying to use Python with Grass GIS. To get started I try to read in a raster TIFF. The import of grass.script works fine: import grass.script as g But if I am trying to run a command I get ...
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2answers
465 views

How to find the shortest route between two points based on cost surface?

I have two locations: (A) starting point and (B) designation. Also I have a slope raster. I want to find the cheapest path between these two locations based on the slope (it is more expensive to ...
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2answers
535 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?
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1answer
583 views

GRASS in QGIS not working (windows XP)

I am unable to use GRASS algorithms in QGIS 2.0.1 (on windows xp). I've already configured the GRASS path. The algorithms seems to work correctly (I cannot see errors in the log), however in the end ...
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1answer
141 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 ...
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378 views

Atmospheric correction for RapideEye without atmospheric parameters

I'd like to perform an atmospheric correction of my RapidEye images but metadata do no include atmospheric parameters required to use the 6s algo implemented in the Orfeo ToolBox. Is there a solution ...
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1answer
152 views

How to set opacity for GRASS layers using command line?

In the process of learning GRASS, I am finding that I can learn many of the command-line methods that I need for scripting tasks from using the wxGUI, as it conveniently shows most of the underlying ...
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1answer
91 views

How to set partial transparency for GRASS layer?

I am trying to style layers in a GRASS monitor such that they are partially transparent. I'm guessing that there's a module for that (d.shadedmap seems close), but I haven't found it. I need a ...
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0answers
233 views

How to Install GRASS Addons to use in QGIS [duplicate]

WIN 7 QGIS 1.8.0 GRASS 6.3.4 I want to use r.viewshed in QGIS. therefore i want to install it in GRASS by using the GRASS interface. Followin Error appears. g.extension.py extension=r.viewshed ...
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175 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 ...
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1answer
151 views

How to duplicate this QGIS workflow with gdal/GRASS? (reproject and crop a raster)?

I have a number of rasters (rgb images) that I want to re-project and crop. I have established a workflow for doing this in QGIS, but I'd like to do it using gdal modules, because the output is being ...
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2answers
112 views

Neighborhood analysis based on occurrence of value

How can I do, either in ArcGIS, grass or another tool, the following: for each cell (pixel), if there is at least one cell with value '4' in a neighborhood of 5 cells around it, reclassify that cell ...
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2answers
895 views

How to set output resolution for gdalwarp to that of source file?

I have a large raster, which I want to re-project and crop for a new location that I'm creating in GRASS. I seem to have gotten the re-projection and cropping right with this call to gdalwarp: ...
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3answers
463 views

Raster map in different zone () than region ()

I am new to QGIS (just installed QGIS 2.0.1) and am having problems running any spatial analysis tools. I followed the instructions on how to call GRASS tools into QGIS, but when I try to run the ...
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1answer
364 views

How to debug “Unable to load GDAL library” error in QGIS 2.0?

I have a problem with r.surf.contour. I create a DTM with v.to.rast.attribute and then use the r.surf.contour and it works fine in QGIS 1.9 but with QGIS 2.0 doesn't work. I have a contour shapefile ...
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1answer
213 views

grass algorithms no longer run in QGIS/Sextante

I used to be able to run GRASS algorithms in QGIS 2.0 via Sextante (Ubuntu 12.04) but not anymore. Initially I would double click on any grass algorithm and the execution would stop with: "WELCOME TO ...
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1answer
116 views

Calling GRASS 6 in GRASS 7 (shell)?

I am running a shell script for batch processing in GRASS 7 (calling it with sh [...sh] in the command line window), which creates a series of rasters through classifications, raster calculator and ...
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1answer
211 views

How to import and patch multiple ASTER files in QGIS?

I'm a new user and just began with GRASS, where I learned to import 30x30 resolution ASTER files and then patch them (the six I'm working with) into one map. On QGIS, it doesn't appear that there's a ...
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2answers
471 views

How does GRASS handle multi-channel images (e.g. landsat)?

I am trying to understand how to use multi-channel images (e.g. landsat or the land-cover data provided by Natural Earth). I am hoping that someone can confirm or correct my interpretation of the ...
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1answer
818 views

How to cluster Raster data

I have thousands of Raster data concerning the ice coverage at the pole at different times (days) over several years. Now I would like to perform a cluster analysis. I want to split the data into ...
3
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1answer
237 views

How to import ESRI Ascii format into GRASS?

I need to take a set of datafiles, generated by our sensor system that reads GPR (Ground penetrating Radar) deviations over a surface as we drive along. I have discrete readings from a set of sensors ...
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2answers
556 views

LANDSAT 8 i.landsat.toar error GRASS 7

I am a bit new to GRASS, but I have managed to get a lot of good work done thus far. However, the following error is really throwing me off, because I can't find any help anywhere for it. I am using ...
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4answers
363 views

Has anyone else been unable to locate and install the GRASS plugin in QGIS 2.0.1?

After uploading and installing QGIS 2.0.1, I am unable to locate and install the GRASS plugin. The plugin is not listed in the 'Plugin Manager'. The 'Plugin_Installer' is also shown in red, ...
3
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4answers
906 views

GRASS 6.4.3 Crashes on Startup; libintl-8.dll cited

I recently installed QGIS 2. I used the advanced OSGeo4W installer that I downloaded from the QGIS download page. GRASS is included in the stack. When I attempt to open GRASS, I receive the following ...
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1answer
258 views

GRASS 7 - raster calculator “and”

I am struggling with one thing in the raster calculator in GRASS GIS 7: I want to create a raster_b from raster_a, with raster_a values between >=-0.15 and <=0.15. The raster containing values ...
3
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1answer
524 views

Solar irradiation calculation using r.sun

I am trying to compute the global solar irradiation for a region and the run times seem to be a bit too high. I have as inputs a Digital Surface Model with the buildings and a Digital Terrain Model ...
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0answers
80 views

grass region resolution error

I am working on a raster, but I can't set a correct region for it. In the Set region to match this raster map field, I select my raster map to change current region, but its resolution does not ...
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2answers
88 views

v.what.rast trouble in GRASS GIS 6.4.2

I'm facing a problem using the v.what.rast comand. I'm trying to update the vector "canali" which represents some streams, with the slope value for every single point of the lines. The slope values ...
3
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1answer
380 views

how can i correct atmospherically landsat 8 images?

I am trying to correct atmospherically an image from Landsat 8 with 6s model from grass 7 and 6.4. Because there are no parameters for Landsat 8 yet, I am trying to give parameters from Landsat 7 ...
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1answer
1k views

GRASS v.Overlay/QGIS Intersect Speed intersecting line and polygon

Im currently trying to convert my scripts from ArcGIS to QGIS but one aspect that is extremely slow (imo) is trying to intersect a polygon with a line feature. I feel as though there must be a better ...
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2answers
202 views

In grass v.drape works with points but not lines

I got an elevation raster map which I interpolate from a point cloud with v.surf.bspline. Then I digitize a couple of points in a new vector layer. With v.drape I'm able to get a height from the ...
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1answer
162 views

create POV-Ray image from DEM-file in grass

I am working on r.out.pov Tool of grass 6.4 creating a POV-ray(beautiful 3D) image from an elevation raster. You can see this link for more information about 3D analysis of GRASS. r.out.pov manual ...
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1answer
76 views

Where do I find the code for gd_calc.py?

I need to create a raster that is the average of a large set of other rasters (many thousands). I've learned from another question that the script gd_calc.py can do a limited version of this, limited ...
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2answers
215 views

How to average a set of n rasters using gdal or other GRASS module? [duplicate]

I need to average a set of n rasters using gdal or some other GRASS module. What command exists for this purpose?
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0answers
162 views

Getting an error when I try to import a loaded vector file to the QGIS GRASS Plugin

I am getting an error code when I try to import a contour line vector file GRASS via QGIS. I have been trying to create a DEM from the contour lines following this tutorial: ...
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1answer
485 views

Basic raster map questions

My bigger problem is to convert a raster map to polygons. I've found some questions that give info and I'm trying to use GRASS GIS as part of that. However, I'm having some basic problems and I can't ...
2
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0answers
493 views

How to specify cost attributes for network analysis in QGIS using the GRASS plugin?

I have a road dataset with information about the length, speed and drivetime for each segment. I use QGIS 1.9 with the GRASS plugin to do different types of network analysis, but how do I set up the ...
0
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1answer
150 views

Does r.in.gdal -o reproject the imported raster data to the location projection?

Does r.in.gdal -o actually reproject the imported raster data to the location projection, or do I need to call gdalwarp to reproject prior to importing?
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1answer
145 views

v.surf.idw on grass return : no data points found

I'm a newbie with grass and I'm using grass (6.4.3) with the GUI... running Ubuntu 13.04 for what it's worth. Here is my region : projection: 99 (Lambert Conformal Conic) zone: 0 datum: ...
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2answers
126 views

Is d.mon xN deprecated in GRASS in favor of something in the wxGUI?

I'm trying to learn command-line GRASS (6.4.3) using the KyngChaos binaries on a Mac (10.8.4) from Neteler and Mitasova's book, Open Source GIS: A GRASS GIS Approach (3rd ed.). I've learned from this ...
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1answer
69 views

Error message starting gis.m in GRASS

I finally broke down and bought Neteler and Mitasova's book, Open Source GIS: A GRASS GIS Approach, because I need to learn command-line GRASS. On trying to work through the book's examples, I'm ...
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1answer
375 views

How to script map production in GRASS?

I'm trying to automate my production of maps with GRASS. What I want to do can be described in fairly generic terms: I have two layers (one vector, one raster), which will be identical in every map. I ...
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96 views

How to Configure sextante in Qgis 1.9 ubuntu

I am using Ubuntu 13.04 and the most up to date version of Qgis 2.1.0-Master. I am trying to get sextante to work correctly and have a hard time. Specifically SAGA 2.1.0 and GRASS 6.4.2 will not ...
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1answer
178 views

GRASS GIS related issues! [closed]

(1) How to create a multiband raster from a set of single band rasters (except when somebody talks about doing a r.composite). I attempted creating a raster3D and it turned out that it is not ...