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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Paths with least elevation gain

I have a DEM of a city with numerous hills and a shapefile of the city streets. I want to find the five paths from a low point A to a high point B on the street network that involve the least ...
2
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1answer
25 views

Return variable with GRASS GIS on a Windows machine

How do I return a variable in GRASS GIS on a Windows machine? For example I set a list of files to define my region. I already figured out that I can't use the bash command export, I need to use set ...
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35 views

Deciding variables for image classification?

The results of an image classification may vary A LOT depending on the variables you use from the beginning. Number of classes, minimum class size, sample interval, atmospheric corrections, ...
0
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1answer
33 views

reading GRASS vector map in python

I know similar questions have been asked several times, but none of the solutions seems suitable for my problem or don't work.. I computed flowlines using the r.flow tool from GRASS GIS, then I ...
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23 views

Module nziv not found in QGIS 2.10.1-Pisa

I want to use nviz in QGIS2.10.1-Pisa on windows 7 and I always get the same warning message : "Module nviz not found", whenever I click on it in the GRASS tools Modules list. I have tried to ...
2
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34 views

“Identity” equivalent in Grass GIS

In ArcGIS and SAGA GIS there is the "identity" tool, which creates a vector overlay and shows area contributions of polygons in shapefile B to the polygons in shapefile A (in the attribute table). ...
2
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1answer
34 views

GRASS plugin for QGIS2.10 missing [duplicate]

I have installed installed qgis2.10 from source on Centos6.6 however the issue i'm facing is that i am missing the grass plugin form the gui. I have checked the plugin manager, its not listed there. ...
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24 views

export several rasters from grass

I'd like to export 127 raster files from grass to .tif in one operation. I already stumbled over this post How to batch export using r.out.gdal command in GRASS but it doesn't work (I don't even know ...
2
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21 views

Using Spyder IDE to develop python for Grass GIS, get 'ImportError: No module named grass.script'

I am trying to use Spyder IDE to develop a python script using python library from grass-6.4.3. I run the script below, and get 'ImportError: No module named grass.script' I am using python 2.7, ...
3
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1answer
28 views

QGIS GRASS raster to GeoTiff

First of all: Windows 8.1 QGIS 2.8.2 Wien My problem is that I used the GRASS module r.watershed to delineate watersheds and get flows with a DEM. It worked fine so everything is OK so far. But ...
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1answer
25 views

Can't access GRASS tools in QGIS [duplicate]

I'm running QGIS 2.6 on OSGeo-Live 8.4 Virtual Machine based on Lubuntu 14.04. I've set up a GRASS (GRASS GIS 7) environment in QGIS, and I have a merged .tif file of LiDAR images open in QGIS, so I ...
2
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1answer
73 views

QGIS 2.10 with ubuntugis dependecies Grass issues Ubuntu 14.04

I saw in How to correctly install QGIS 2.8.3 with GRASS plugin on Ubuntu 14.04? how to get Qgis 2.10 running from the non ubuntugis repository with grass features but I'm still having problems with ...
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7 views

Sky View Factor of building roofs => Vector algorithm [duplicate]

I'm currently working on a project in which I'm trying to assess the SkyViewFactor of a given roof using building vector data. I've already managed to build a process based on vector rasterization ...
4
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2answers
169 views

How to correctly install QGIS 2.8.3 with GRASS plugin on Ubuntu 14.04?

I already tried to install QGIS 2.8.3 using the procedure described on: http://www.qgis.org/en/site/forusers/alldownloads.html#debian-ubunt, but grass-plugin do not compare on plugin list! I tried ...
2
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1answer
49 views

GRASS: Landsat 8 GeoTIFF import error

I'm trying to import some Landsat 8 GeoTIFFs into GRASS (in QGIS), and I can't work out why I'm getting this error, or how to fix it. No amount of Googling has been able to tell me anything at all. I ...
0
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1answer
26 views

r.report giving only per-class cell count

I'm trying to extract the count of each pixel value in a raster, like in this question: How to extract pixel value counts from a raster in QGIS? However, when I run r.report (from QGis (2.10) ...
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1answer
32 views

QGIS + GRASS: r.in.gdal “View output” produces “cellhd file (…) does not exist”

I'm working with a recently installed QGIS (2.10.1) + GRASS (6 v2.0) package, and have been working with some rasters and vectors in QGIS that I'd now like to play with using the GRASS tools. I've ...
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3answers
50 views

Grass GIS: ArcGIS' “Raster to polygon” equivalent

I've got a small clipped extent of a LANDSAT image and I need to have the single pixels as polygons in order to tell the overlap proportions of overlaying polygons. In ArcGIS I used "Raster to ...
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0answers
48 views

Trouble with kernel density estimation

I have been trying to find out how to make the SAGA and GRASS kernel density tools work in QGIS 2.8. I have had a lot of trouble trying to get them to work as they produce useless results seen below. ...
3
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1answer
39 views

How can I change the way r.cost and r.drain modules work?

Look at the picture #1. This is my cost surface raster that has only 2 values. Area restricted for path to cross (red one) and area that is free to go (yellow one). As I need it and as I undestand how ...
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34 views

Problems using GRASS tools for topology validation in QGIS

I'm working with a shapefile of Enumeration Districts (Setores Censitários) of the 2010 Brazilian Census. Enumeration Districts (ED) are smallest areas for which Brazilian Census data is available. ...
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50 views

How do I use r.horizon in QGIS?

I have a raster file I wish to find the horizon angles from. I am currently using QGIS 2.10.1-pisa (the latest updated version) with the GRASS plugin (6.4.3 and 7.0). I have a raster file generated in ...
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1answer
31 views

Grass gis or Qgis trade area?

I know it's possible to make a trade area (service area) in ArcGIS. But Is it possible to make a trade area with a network data set in Grass GIS or QGIs?
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42 views

GRASS 7 Cost surface and elevation points development

I'm a new to GIS and I need some help. At the moment, I'm trying to develop an optimal path across an area by using GRASS 7 features. It is very similar to the task given here. The problem is that I ...
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1answer
12 views

how to do horton analyis on single catchment in grass gis

I have generated streams using r.stream.extract and used r.stream.order then I have tun r.stream.basin using inputs from r.stream.order. I am getting multiple basins. How to select a single basin and ...
2
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1answer
142 views

How to use GRASS v.kernel to calculate point densities along a network?

In a road network, I need to select the segments where a minimum of 5 dots occur (1 dot = 1 address) over a distance of 100 m (the image attached illustrates my question). I'm trying to use GRASS ...
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1answer
28 views

atmospheric correction using Grass

I am using i.atcorr for atmospheric correction in Grass6.4.4. I would like to add Landsat8 sensor to my project(build). If I copy the iwave.cpp file from grass 7, I get error messages. Do I need to ...
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15 views

GRASS7. Parallel import shapefiles failed

I am trying to import a 8 ShapeFile to GRASS V7.0.0. Each shapefile's size is between 80 Mb and 300 Mb. For this purpose, I've used multiprocessing in python. I run 4 parallel processes, each one ...
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0answers
48 views

64 Bit Win 8.1 grass 7 missing dependency

I searched for an solution but couldn't find it. Problem is: previous i had an working grass 7 within qgis 2.6/2.8 I know that there were more people with the same issue. When executing a grass 7 ...
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1answer
35 views

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 ...
2
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1answer
47 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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4answers
252 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 ...
4
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1answer
42 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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1answer
44 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 ...
2
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1answer
110 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 ...
0
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1answer
41 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, ...
3
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1answer
56 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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1answer
42 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 ...
2
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0answers
48 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 ...
1
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1answer
54 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 ...
2
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2answers
80 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 ...
1
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1answer
57 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? ...
3
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1answer
33 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: ...
2
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1answer
161 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 ...
4
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1answer
56 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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22 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 ...
3
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1answer
36 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 ...
1
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1answer
62 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, ...
2
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1answer
58 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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13 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 ...