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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6
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3answers
310 views

Cutting out depth information in raster. Calculating volume in Qgis

I am trying to calculate habitat volume for around 30 fish stocks in Qgis. I have habitat areas (shape files) and Bathymetric information (.tif file). I believe I can calculate the entire volume of ...
1
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0answers
48 views

using r.volume model GRASS plugin in QGIS

I am calculating volume of bathymetric data in the form of a clipped raster in GRASS with a Custom Lambert projection centered around 70degrees North, using the module r.volume in GRASS. Side note: ...
3
votes
2answers
68 views

GRASS GIS not starting

Hello my name is Luca and I write from Italy. I have a problem with GRASS GIS 6.4.3. Last week I installed QGIS 2.4 with GRASS GIS 6.4.3 GUI on Windows 7 64 bit - admin user. When I click on GRASS ...
3
votes
1answer
83 views

ArcGIS Desktop equivalent to GRASS r.geomorphon algorithm?

I would like to know if in ArcGIS Desktop 10 there is some tool/algorithm which can be used to perform the same analysis that r.geomorphon does in GRASS 7.
1
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0answers
39 views

QGIS OD matrix assignment on network

Using QGIS, I would realize an assignment of an OD matrix on a network, like this one on Transcad. I have: - network - points of Origin and Destiny - flows of traffic for each OD I found a solution ...
1
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1answer
194 views

Loading GRASS gives error installing QGIS Chugiak on Windows 8.1?

I am experiencing a problem installing QGIS 2.4 Chugiak on Windows 8.1, resulting in a error loading Grass. This may be a problem only affecting certain installations, I'm not sure. I am a noob on ...
1
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2answers
108 views

How can I import tif file in GRASS GIS

While importing TIFF image to GRASS GIS, I get an error: Location PROJ_INFO is: name: Lambert Conformal Conic proj: lcc datum: nad83 a: 6378137.0 es: 0.006694380022900787 lat_1: 36.16666666666666 ...
1
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2answers
485 views

How to create GRASS scripts in C# in Windows

Most of the tutorials that I have seen are under Python and Linux. Is it Possible to create GRASS scripts in C# or atleast in Windows. I can create scripts using a different language as a compromise ...
1
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0answers
17 views

GRASS GIS and Liss4MX

i am working on grass gis. how to use grass gis for liss4 of IRS-P6.I have to do atmospheric correction for hilly terrain data.i would like to use grass's i.atcorr. may i know the dependencies and how ...
0
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0answers
19 views

How can I implement GRASS GIS flow direction process from DOS scripting

When I try to implement its showing it work completely in its command prompt(grass) and creating output files also but when I try to view the result its not showing anything in Map Display I ...
2
votes
1answer
101 views

How to properly open an ASTER data?

Yesterday i downloaded an Aster L1B image from USGS's website. If i load it in QGIS, it doesn't get displayed properly(location wise). Even after i've enabled "On the fly" option, it's not reading the ...
0
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1answer
32 views

trying to calculate volume using r.volume GRASS - error message

I am trying to calculate volume using GRASS plugin in Qgis using module r.volume however the attached error message keeps appearing. Any ideas?
1
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1answer
51 views

Error importing raster into GRASS plugin in QGIS

I am trying to import a tiff raster file into GRASS however every time I do this the below error message comes up. I am using a custom CRS so I have tried changing it back to the default CRS but still ...
4
votes
2answers
3k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
2
votes
0answers
100 views

How to merge overlapping and duplicate lines from vector layer to one single line?

I used the "polygone to line" tool from QGis, to get a line-layer from this polygon-layer: unfortunatly this causes overlapping and duplicate lines, after I broke the qgis-export via GRASS into ...
2
votes
1answer
40 views

How to convert tif to dep extension?

In white box when i try to import or do any processes it's asking .dep extension How can i convert .tif into .dep extension?? If try to pass LISS3 data in GRASS GIS it is taking as single bands. So i ...
1
vote
1answer
36 views

Setting resolution for GRASS raster

I am trying to calculate volume using the GRASSplugin. I have my area information in vector format and my depth information in raster. I read that it is important to set the raster resolution before ...
3
votes
1answer
65 views

Merge different Landsat scenes in Grass GIS

I am new to Grass GIS, and I really need some help in solving this issue. I have 17 scenes from Landsat8 covering an area. I have created color infrared images of bands 5,4,3 and now I want to merge ...
3
votes
3answers
243 views

GRASS v.generalize method=douglas not working as expected

I'm frustrated with v.generalize trying to simplify polygons. Those polygons stem from ArcGIS's raster to vector function (imported into GRASS from Shapefile), so they are pretty zigzag like this: ...
4
votes
3answers
223 views

LiDAR data density, returns per square meter

How can I compute a raster showing the number of return points per square meter using SAGA GIS or other open source software? My goal is to obtain a mask which would show me the places (cells) ...
2
votes
0answers
150 views

Problem loading output layer QGIS

Every time I run operations with temporary file output from the graphical modeler, I get the following error message: Oooops! The following output layers could not be open CLIP: ...
1
vote
1answer
43 views

My RapidEye image won't appear in GRASS GIS

I have several RapidEye images that I want to use for object segmentation in GRASS GIS. When I import the the bands they all look like this and the same goes with a RGB composite: I've used these ...
-3
votes
1answer
287 views

How to extract drainage line network from GRASS GIS and QGIS [closed]

Giving DEM as input is there any way to get drainage network? I am newbie to GRASS and QGIS ,provide any working examples in GRASS GIS and QGIS with procedure.
1
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0answers
33 views

Create “grid” of polygons with the same 3D area based on an underlying raster variable (e.g. DTM height)

This could apply to point or raster values but imagine a raster of a continuous variable such as height (DTM). Is there a way to create a complete coverage of polygons that will have an equal area, ...
2
votes
2answers
215 views

How to create isochrones from streets with distance values?

I have made isochrone lines using GRASS and QGIS, as shown. The lines show various distances to fire stations on a street network. Now I would like to turn these lines into polygons that look like ...
3
votes
3answers
155 views

Can a shapefile, or other file, be made from Excel without coordinates

I have two Excel spreadsheets I'd like to make into shapefiles, or some equivalent. I have access to ArcGIS at work and want to try using GRASS as well. I have seen the help on doing so, but only if I ...
2
votes
2answers
149 views

Resolution difficulties in Grass

I have gone through similar questions to mine here, but I didn't find a solution. Please help! When cropping a raster image by using g.region & r.mapcalc, I get a new image but the resulting ...
5
votes
2answers
446 views

How to split lines into equal segments with QGIS?

I'm attempting to split a curved (wiggle) line into equal length segments. Have used Grass's v.split which works to a degree but does not provide the output I'm after. v.split will extract segmented ...
4
votes
2answers
4k views

How do you Turn on the GRASS plugin in Quantum GIS?

I downloaded and installed Quantum GIS 1.5.0 with GRASS using the OSGeo4W installer on my Windows XP machine. Unfortunately, when I go to Plugins>Manage Plugins I cannot find the GRASS plugin. When ...
1
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1answer
26 views

DEM error when trying to do topographic correction in GRASS

I'm new to GRASS gis and I'm trying to do a topographic correction (i.topo.corr) of 9 ASTER bands using SRTM dem. I keep getting this error message: ERROR: Illumination model is of CELL type Is ...
1
vote
1answer
31 views

3D rubber sheeting using ground control points

I have 3d lines that I would like to rubber sheet or rectify in 3D (including z rectification). I used ogr2ogr with -gcp, however all the vertex of a polyline were set to a single elevation, and since ...
16
votes
2answers
6k views

What's the relation between QGIS and GRASS?

I have been working with GIS and remote sensing in an university and professional environment some ten years ago (ArcInfo etc), so I have some experience even though somewhat outdated Right now I am ...
3
votes
1answer
72 views

Underwater terrain modeling

My task is to model the surface of a lake bed, calculate volume of it and visualize it as 3D a surface. I have acquired depth measurements in a small lake using echosounder. The precision should be ...
2
votes
0answers
69 views

best method for gridding or interpolating elevation data

I wonder if someone can recommend the best method for gridding elevation data in QGIS, GRASS or similar. The elevation data I have is collected along 1m spaced lines at approximately 1 reading per ...
3
votes
1answer
42 views

Why GRASS 7.0.0 can't create a table while importing shapefiles from QGIS?

I use GRASS7.0.0Beta1 and QGIS 2.4.0 on Windows8. With v.in.ogr, when I import a shapefile, I get the error message "Unable to create table". When I put the option of not importing the table, the ...
1
vote
1answer
47 views

Import shapefile into GRASS in QGIS

I am using the GRASS interface in QGIS 2.4. I have successfully imported my shapefiles into GRASS using v.in.ogr, but when I try to then use a GRASS tool, like v.net Network maintenance, the select ...
1
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1answer
29 views

Create Addons for GRASS GIS

Is there a complete guide - example describing how to create an add-on/plugin for the GRASS GIS? I would like to extend the GUI with extra menus and toolbars creating extra functionality.
8
votes
1answer
858 views

How to pan-sharpen Landsat images for image-classification in GRASS?

I'd like to learn how to do an unsupervised classification of a Landsat scene using i.cluster > i.maxlik in GRASS using pan-sharpened 15m-resolution images (the example given in its Wiki uses the ...
0
votes
1answer
39 views

How to batch export using r.out.gdal command in GRASS

I created a list of files (NPPFILES) using g.mlist command in GRASS 7. Now I would like to export these files as .tiff files. I tried this command in GRASS prompt for files in $NPPFILES; do ...
0
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0answers
41 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 ...
0
votes
0answers
22 views

PostGIS commands in GRASS

How does the geometry get referenced in GRASS when using a PostGIS command like st_within? e.g: echo "UPDATE file SET within=(select file2.name from file, file2 where st_within(file.geom,file2.geom) ...
1
vote
1answer
44 views

r.sun delievering unrealistic Values

I need your help. I'm trying to calculate the global irridiation for a specific area. I'm interested in the results for rooftops in special. I have a DEM, calculated slope, aspect and horizons and ...
1
vote
1answer
38 views

Preserve polygon boundaries when vectorizing a raster according to a polygon vector

I have a raster which I clip by some polygons and then convert to polygon. I would like to obtain the same number of polygons in both my vector files. The problem is that some areas in the vector ...
1
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0answers
93 views

How to create least-cost path between two polygons with GRASS?

I am completely a beginner in GRASS but I would like to use it to have the cumulative cost of moving between two polygons. More exactly, I would like to get the smallest cost from any point situated ...
0
votes
1answer
51 views

removing spurious lines in raster before or after vector conversion?

I'm looking for a feature/function in either python opencv/ndimage/gdal/etc. or qgis/saga/grass that will help clean up a skeletonized image that I'd like to vectorize into a shapefile of ...
2
votes
0answers
415 views

QGIS cannot open output layers

I have problem with QGIS 2.0.1. Everytime I run tool from SAGA or GRASS, I get exactly the same error, for example: Oooops! The following output layers could not be open Channel Network: ...
3
votes
0answers
110 views

Pan sharpen Landsat 8 using Grass 7

I have followed this great tutorial on pan sharpening using Grass GIS 7 (I'm using beta 3). Everything in the tutorial seemed to have worked, but my final output is not as expected (pictured below). ...
0
votes
1answer
57 views

Error G_Calloc v.to.rast

Using the grass GUI I get this error message: ERROR: G_calloc: unable to allocate 2004389888 * 8 bytes of memory at raster.c:71 What can i do to remedy this?
1
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0answers
19 views

Free And Open Source Software Tools to orthorectify Pleiades imagery [duplicate]

Are there Free And Open Source Software Tools to orthorectify Pleiades, Worldview And Quickbird imagery as we do with COST tools such as ERDAS Imagine, PCI, ENVI, etc.?
2
votes
0answers
98 views

3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS

How can I make 3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS? I am quite new with GRASS. I have only managed to get a 3D view of the terrain so far.