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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108 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 ...
1
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0answers
17 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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0answers
21 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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0answers
137 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 ...
1
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1answer
84 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 ...
0
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0answers
27 views

suggestions for open source GIS in monitoring [duplicate]

my name is weng and i am currently conducting my research Entitled "Architecture for GIS based monitoring system for malnutrition" and one of the requirement would be to identify what open source GIS ...
1
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1answer
101 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 ...
2
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4answers
530 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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2answers
177 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 ...
4
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2answers
513 views

How to enable GRASS plugin in QGIS 1.8.0 (Linux Mint 13 - 64 bit)?

Every time I enable GRASS plugin in QGIS (Plugins -> Manage Plugins -> GRASS), I got a message: Exception - G_getenv(): Variable GISDBASE not set. I googled and found some information here but don't ...
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0answers
98 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 ...
2
votes
2answers
336 views

Flow modeling and FOSS GIS; lahars and HEC-RAS

What are the options for FOSS flow modeling of dilute debris flows in QGIS or GRASS? Have you, or can you refer me to studies where the authors, tested these models/plugins/functions/etc. for use in ...
0
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1answer
66 views

Adding additional nodes to network in Grass GIS

I have created a network in Grass GIS (using v.net, nodes option). I then want to "disrupt" the network (i.e., create some road blockages) and add in nodes to the new line ends where road blockages ...
4
votes
1answer
157 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?
0
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1answer
64 views

How do I install mdenoise?

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 ...
2
votes
1answer
241 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 ...
0
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1answer
41 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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2answers
58 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 ...
2
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0answers
151 views

How to Install GRASS Addons to use in QGIS

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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0answers
86 views

where to perform principal components analysis and tasseled cap transformation

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 ...
8
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371 views

SEXTANTE toolbox - GRASS error

I am trying to use the SEXTANTE module GRASS (and SAGA) for vector analysis but whatever function I use I always get the same error:"Could not load layer: G:/closest.shp Check the SEXTANTE log to look ...
3
votes
2answers
194 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: ...
1
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1answer
141 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 ...
3
votes
1answer
115 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
227 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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2answers
140 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 ...
6
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6answers
309 views

Tool/Algorithm for generalizing OSM-Files for printing maps

Is there a tool or algorithm to (topological) generalizes OSM-shapes? I would like to build a printable map in different scales. In the image below you can see the same divided road (yellow) at ...
0
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1answer
105 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 ...
5
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2answers
313 views

Is there an open source alternative to ArcGIS for Desktop's Integrate tool?

I need to snap about 1000 lines in one layer to the lines in another layer (there are about 5000 lines in the second layer). The lines to be snapped are about 15 map units away from the base layer ...
0
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2answers
127 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
502 views

Using Landsat 8 for quantitative analysis - what DNs does GRASS require?

Hoping someone can short circuit a lot of exploration Landsat 8 values are stored as unint16 since the sensors work on a range 0 to 4096 whereas the L7+TM was 8 bit and had a digital number range 0 ...
0
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2answers
57 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 ...
1
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1answer
77 views

GRASS 6.4.3 Landsat processing

what are the pre-processing steps required for landsat etm+ with GRASS 6.4.3 prior to land cover change detection? The product used is L1T.
0
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1answer
82 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 ...
2
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0answers
137 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 ...
7
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0answers
533 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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0answers
40 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 ...
0
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1answer
71 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 ...
0
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1answer
188 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 ...
0
votes
1answer
71 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 ...
0
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2answers
110 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
64 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: ...
2
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0answers
206 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
votes
1answer
70 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?
0
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1answer
61 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: ...
0
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1answer
39 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 ...
0
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1answer
140 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 ...
0
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1answer
122 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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86 views

QGIS GRASS Rasteranalysis (r.los)

I want to determine the area around a wind turbine from wich the object is visible. I want to use r.los in GRASS i get this error: (German) r.los input=dgm@sichtbarkeit coordinate=534228,5406743 ...
0
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1answer
90 views

Cannot import Grass in Console of Qgis (1.9.0 Master)

I can't import Grass in Console of Qgis (1.9.0 Master). I am guessing it is because of some Grass environment variables which are not set up correctly. However I don't understand why it is working ...