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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GRASS GIS Data display

I have import data vector and raster into GRASS GIS database. I try several projection and i dont know why i cant display the data in Grass GIS. But i can display my data with the grass plugin in ...
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91 views

How to calculate the 3D length of line segment in QGIS?

I've been looking through all of the GRASS commands in the QGIS 2.10 processing toolbox and it seems like one of these must be able to do this but I haven't found one yet. There is 'v.sample' which ...
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1k views

Grass toolbar for QGIS 2.10

I don't see the GRASS toolbar in QGIS 2.10 (Pisa). There are still GRASS commands in the Processing toolbox. I know there was some upgrade of GRASS for 2.10. Is the toolbar not available anymore? If ...
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47 views

What is the “t” in i.landsat.toar

I'm using GrassGis 7.0.0 for Landsat imagery. In the description of i.Landsat.toar under dos3 and dos4 is: TAUz = exp[-t/sin(e)] What is "t"? I cannot find any description about what it is. Can ...
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58 views

Identify nodes in GRASS

Apologies if this is a really basic question but I have been unable to sort this out: How do I identify nodes in GRASS? Specifically, I am running a Salesman analysis and get the following error ...
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415 views

Where is the “Add vector layer”-button in GRASS 6.4.4. plug-in QGIS 2.10.1?

I've just downloaded and installed the new version of QGIS 2.10.1 with GRASS 6.4.4. When opening a new GRASS mapset and importing layers, I missed the button "Add a new vector layer". I've updated ...
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57 views

Using GRASS7 algorithms via WPS - best practices

I need to set up Linux server (Debian or Ubuntu), which provide GRASS7 algorithms via WPS. I have some attempts with 52°North WPS, but without any success. Also there are many other ways how to do it, ...
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80 views

Is it possible to have v.in.lidar without compiling GRASS?

I already have installed libLAS like this: sudo apt-get install liblas-bin And Ì have installed GRASS GIS 7 from the ubuntugis-unstable repository. Is it possible v.in.lidar without compiling ...
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85 views

How can i import raster image to GRASS GIS without losing RGB Values?

I am using GrassGIS 6.4.2, How can I import raster data to GrassGIS without losing RGB Values? The raster image format is TIFF, the below commmand is using to import raster image: r.in.gdal ...
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80 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or ...
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181 views

Elevation data from 3D shapefile of buildings to raster DEM

I have acquired LoD2 building models in the 3DShape format (Polygon ZM). This LoD2 data needs to be prepared for a R-script of solar irradiation calculations on roof surfaces, but which can only ...
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126 views

Suitable Raster processing methods to extract field boundaries from images

I'm trying to extract field boundaries and features from a lot of aerial images of agricultural land - and avoid digitizing these features manually. I've managed to get a crude raster file of the ...
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1answer
166 views

What's difference between Topology and Check Validity in QGIS?

I would like to know what the difference is between the Topology Checker and Check Validity tools? Is there anyone who knows of a good document or tutorial that explains functions of these tools? ...
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1answer
47 views

QGIS Convert bathymetry shapefile from fillable to strokeable

In Java I would like to stroke the bathymetry depth lines instead of filling the area. I'm starting with the Natural Earth Bathymetric Data: ...
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1answer
322 views

Grass 7 no longer works via the Processing Toolbox on Ubuntu

When I try to execute a Grass 7 algorithm via the Processing Toolbox in QGIS 2.10, 2.8.2 or 2.8.1, I get the following error: Missing dependency. This algorithm cannot be run :-( QGIS ...
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3answers
109 views

How do I count the number of vector lines that pass though a given raster cell?

I am working on a project (currently in GRASS7 though I'm not against exporting to Arc or R or other software if necessary) where I am generating thousands of shortest cost paths (using the r.walk and ...
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0answers
64 views

QGIS Training Manual - Lesson 12.2.1 (GRASS GIS) - r.colors.table module does not color raster

I am going through the QGIS Training Manual, Lesson 12.2.1 ("Follow Along: Set Raster Colors) and noticed that the 'r.colors.table' GRASS module did not color my DEM raster layer which I imported via ...
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1answer
56 views

Simplify / generalization of flow lines

I'm trying to make a model of surface runoff of rain water. I'm using GRASS GIS function r.flow, which generates nice smooth lines of runoff. What I need is edit these flowlines someway to avoid ...
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1answer
159 views

Compile QGIS from source (with Grass)

I recently decided to reinstall QGIS and build against the latest version of GDAL - something I have been putting off for ages because I suspected it would be a nightmare. Lo and behold it has been, ...
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1answer
99 views

Processing algorithm fails from Python script

I'm trying to write a Python script performing a geoalgorithm. What is surprising me is the following: I first test the algorithm by QGIS (2.8) interface. In my case, the GRASS interpolator ...
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1answer
42 views

GRASS problem - r.viewshed.cva addon

I'm a very beginner at GRASS. I'm using GRASS 7.0 and I tried to install r.vieshed.cva extension. When installed, if I type it in the command line, it appears "r.viewshed.cva" is not recognized as ...
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2answers
182 views

GDAL/QGIS broken Ubuntu 14.04

I think I've managed to bust GDAL after (I think) installing Grass7. I had previously built GDAL (1.10) from source with a bunch of additional drivers. When installing Grass7 GDAL 1.11 was installed. ...
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31 views

Grass 7 import shapefile problems

I'm just messing about with Grass 7 (installed fine on Ubuntu 14.04 - well no errors at least). I'm trying to import a shapefile using v.in.ogr and when presented with the dialog box, browse for my ...
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536 views

Create raster with grid cells values based on area covered by polygons

I have a polygon data with area covered by the forests (data is here - https://www.dropbox.com/s/zgckliydalljw6a/sp_data.zip?dl=0). I want to convert polygons to raster. The value of each grid cell ...
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28 views

GRASS r.inund.fluv example of input files

Does anyone have an example of input files for the GRASS r.inund.fluv add-on that can be shared. I am asking because I am getting some errors when I am trying to run an the files that I created and I ...
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166 views

Removing pseudo-nodes using QGIS Sextante plugin?

I have a road network (vector) that i'm interested in carrying out some space syntax analysis on. Predictably my GIS data is in a pretty terrible state. For example, there are a bunch of roads on the ...
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70 views

Converting a (WAsP) vector map to a raster map with GRASS GIS

i'm quite new to GIS and i need to convert roughness data which is available in a vector format to a raster format. The final data should be on a simple 2-dimensional uniform grid with a constant grid ...
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1answer
68 views

Creating input node file for V.net.salesman in GRASS?

I have imported line vector layer and point vector layer(12 points) to grass using v.in.ogr. Now i want to use v.in.salesman to find shortest path between these 12 points, but i couldnt input ...
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64 views

registering MODIS in GRASS as space-time dataset

I have a problem using the space time module in GRASS GIS (7.1 for Ubuntu). I have a MODIS time series with 8 day interval, so 46 images per year. So I created a file (filelist_grass.txt) containing ...
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70 views

Drawing “proportional” buffer using QGIS or GRASS?

I'm working on aquatic vegetation and have a shapefile representing floating vegetation in a lake. By some studies, we know that submerged vegetation extends for a certain extension based on floating ...
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104 views

Why is r.sim.water out of memory (ERROR: G_calloc) in GRASS GIS?

I'm having trouble with GRASS GIS. I'm new to GRASS GIS, I have played around and also searched the internet and the Wiki, but found nothing really helpful, so this is my last chance :) I wanted to ...
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149 views

Error: GRASS 7.0 and QGIS 2.8.1 in Linux Mint from the ubuntugis-unstable

I have installed GRASS 7 and QGIS 2.8.1 from the https://launchpad.net/~ubuntugis/+archive/ubuntu/ubuntugis-unstable (Trusty 14.04) in Linux Mint 17.1 64bit(sudo apt-get install postgis libgdal1h ...
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1answer
126 views

How can I create polygons for a 3D map from a DEM in grass/qgis

I have a SRTM 30m DEM of my area. I want to create a physical 3D terrain map from it (from felt, 3D printer, you name it). I have two questions about this process: With grass r.contour I created ...
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1answer
57 views

Error when installing a GRASS addon!

I am trying to install r.inund.fluv on Linux to produce inundation maps but I am getting the below error. Note that I have a Fortran compiler. Any help with this matter would be highly appreciated. ...
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2answers
80 views

How to use r.mapcalculator to change values within a raster cost map to negative

I have created a cost map in r.cost module in GRASS (through QGIS). This is actually a distance map from a protected area and distance from protected area has been calculated in both directions. How I ...
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1answer
75 views

GeoTiff exported using GRASS will not open in other programs

I am trying to export an image group as a multi-band GeoTiff using the r.out.gdal module in GRASS. For some reason I cannot get ArcGIS to recognize my GeoTiff exports. I have tried opening the file in ...
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46 views

Linearising aspect in GRASS GIS

After having produced aspect of surface in GRASS GIS and being aware that GRASS GIS calculates aspect counterclockwise from east, how could we transform aspect from being a circular variable (0-360 ...
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31 views

Mod function in GRASS GIS

What is the equal of ArcGIS Raster calculator "Mod" function (Finds the remainder of the first raster when divided by the second raster on a cell-by-cell basis.) in r. mapcalc in GRASS GIS?
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63 views

Execute GRASS command within QGIS python console

We try to calculate catchments with the r.water.outlet function from python console. To do so we use the following code: import processing rlayer = QgsRasterLayer("/my/path/DrainageDirection.tif", ...
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0answers
57 views

Convert manual colored maps to vector

Is there a way to colorimetrically and automatically vectorize georeferenced rasters that came from manually colored, scanned maps? Currently we Print the topography maps 20k scale --> hand-coloring ...
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103 views

From Landsat spectral radiance (W/m2*sr*µm) to Global horizontal irradiance (W/m2) for mere mortals

We are working in a solar energy project to locate potential sites for solar panel farms. We are using the Landsat 7 panchromatic band to derive radiance with GRASS using i.landsat.toar (W/m2*sr*µm ...
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1answer
58 views

comparison of atmopsheric correction methods

I have noticed that dos methods for atmospheric corrections are in the section of radiometric correction (i.toar) on grass gis.Does that means that dos is a method doing radiometric and atmospheric ...
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0answers
146 views

Raster Not Loading into Map Display - GRASS

I am very new to GRASS and I have been trying to load a raster using just the GUI. I have set my project to the projection of my .tiff file and extents. Using file > import raster I select the .tiff ...
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37 views

What logical function should i use to do a union of two raster files in GRASS?

The files are : DEM and roads. For the following i did euclid distance and then reclass. Now i need to know with what logical function to combine them elevation rank ...
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GRASS watershed analysis add storm inlets

Try searching for this with no luck. I am using r.watershed to delineate flow directions, subwatersheds, etc. All good, except that storm drain inlets, culverts and subsurface drainage courses are ...
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2answers
149 views

Use GRASS through R

I want to use GRASS GIS 7 through R 3.1.3 in kubuntu operational system. Could someone help me connect GRASS with R, and use GRASS commands through R (not the other way round!).
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1answer
81 views

How to add my own GRASS algorithms to Processing?

I need to use algorithm r.bioclimatic from GRASS in QGIS but I see that this algorithm don't exist in Processing Toolbox. A search a way of add this algorithm to Processing and in GRASS and Sextante ...
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0answers
87 views

Steiner tree problem: Optimal routes for Fibre planning on road network

I am trying to solve a large optimization problem where I have a set of nodes on a road network that need to be connected using fibre using the shortest possible amount of fibre. The problem is a ...
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1answer
104 views

topographic correction using GRASS 7.0 (**i.topo.corr**)

I would like to apply topographic correction using GRASS 7.0 (i.topo.corr). The imagery were already converted from DNs to Top-of-Atmosphere Radiances. When I apply the i.topo.corr command it runs ...
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57 views

Why is QGIS 2.8.1 crashing when enabling Grass Plugin?

I am running Linux Mint 13 "Maya" (Ubuntu 12.04 Precise). I installed Grass via the software center. Than I installed Qgis 2.81 following this procedure: Add the lines for one of the repositories to ...