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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1k views

Create a 3D surface from xyz csv using GRASS

Apologies if this is a repeat question guys. I am trying to create a 3D bathymetry surface from xyz data. There is approximately 300,000 points with lat, long and z (depth data). The data is sonar ...
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1answer
112 views

What does v.distance calculate excactly?

As I am from an economics department, I am quite a beginner in QGIS. I read, that if I wanted to calculate the distance from a polygon to a point/line/other polygon, I should use the GRASS plugin ...
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2answers
41 views

GRASS GIS - Plot Legend using Text Only Version

If a person uses the text only version of grass on a remote system, how do you output the legend as a graphics file? such as: r.out.tiff input=mymap output=file.tiff but have it print the legend ...
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1answer
65 views

can grass gis module be used in parallel mode

i want to use my customized grass gis(6.4.3) module for separate bands of a sensor in a parallel mode. is it possible? i have created separate location and if one band is executed ,for the second band ...
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0answers
25 views

Is there a lower bound on the std deviation for v.kernel in GRASS?

I'm using the v.kernel function in GRASS to create heat maps. I am able to generate an acceptable heat map using a std deviation of .2 and a several thousand rows and columns. After the map is ...
2
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1answer
140 views

Find lakes on an elevation raster

I would like to know if there is a way to identify lakes based on an elevation raster (like SRTM or ASTER)? As far as I can understand, it would mean identifying any cell below the elevation of ...
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117 views

How to make DEM raster in Google Sketchup?

I would like to make DEM in google sketchup, later add 3D buildings and finally convert this file to raster. Afterwards, I want to import this raster to GRASS GIS to make solar maps. It is possible to ...
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1answer
66 views

Errors while building grass-7.0.1 with Msys/MinGW

I need to build grass-7.0.1 for qgis on Windows 10 with Msys/MinGW. I succefully installed all packages from general and several packages from optional requirements. Here is my configure options ...
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136 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
76 views

GRASS mapcalc in Python Shell

I'm trying to convert my GRASS/Bash script into the Phython Shell. Now I have a raster dataset (test.01) which I want to convert in 1 or 0. In GRASS I used the command r.mapcalc r.mapcalc ...
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1answer
126 views

How to merge vector buildings height layer with raster DEM to get solar maps in r.sun in Grass GIS?

Welcome, this is my first post. I have vector layer with buildings heights and vector/raster DEM file. I need to create solar maps with sun radiance values on the roof (and on surface, ofc). I am ...
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1answer
57 views

How do I get the distances to every cell in GRASS?

I have an elevation raster map, a point, a raster map defining the viewshed from that point, and now I want to produce another raster map with the results of a function of the distance between the ...
3
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1answer
41 views

Visible altitude across a raster from a point

I have a raster surface model and I'm trying to determine the height an object would need to be at to be visible from an arbitrary point at an arbitrary altitude. I am currently using Grass and have ...
4
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2answers
406 views

95 percent volume contour

I generated, from point data, a kernel density map using GRASS, and I would like to identify the 95% volume contour in it. Is it possible in GRASS? Thank you
1
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1answer
111 views

GRASS 7.0 fill.dir crash

I am working on a 13407 lines * 11050 columns raster file (SRTM DEM, 30m) with a script that calls a series of hydrological modules in GRASS 7.0. The system I am using is a Windows server 2012 R2, 64 ...
2
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2answers
226 views

Deciding variables for unsupervised image classification?

The results of an unsupervised image classification may vary A LOT depending on the variables you use from the beginning. These are the variables for the tool in ArcGIS:number of classes, minimum ...
2
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1answer
281 views

Extracting polyline of border between differing polygons using R or GRASS?

I have a shapefile with polygons with an associated variable that can take different values. I would like to extract the borders between polygons of differing value (red and blue) as a polyline (dark ...
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1answer
54 views

2.10 program group option to open QGIS with GRASS

I have installed QGIS 2.10 on Windows 8. I cannot find the 'option' to start QGIS with GRASS - as has been previously answered. Have I possibly missed something in the install? Is this 'missing' ...
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1answer
291 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
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1answer
62 views

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
42 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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1answer
68 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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0answers
156 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 ...
3
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2answers
289 views

Issue while running grass from subprocess

I have a map based web application using geodjango. I needed to display the crime hotspots within a selected polygon area. I found that v.kernel is very good for generating heatmaps/hotspots. So in my ...
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0answers
54 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). ...
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1answer
536 views

Connecting Grass with R

I need help to connect R with Grass. In RStudio when I send the line: loc <- initGRASS("C:/Program Files/R/R-3.1.0/bin/i386", home=tempdir(), override=TRUE) It says: Error in ...
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62 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 ...
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1answer
359 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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1answer
108 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 ...
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1answer
4k views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
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0answers
104 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 ...
2
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1answer
61 views

Extracting area from DEM Raster?

After applying constraints to the DEM I polygonised the raster (using GRASS r.to.vect.area) The result is shown below with a lot of vector with resolution = [30 * 30] Is there any solution to make ...
3
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1answer
575 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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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 ...
2
votes
1answer
106 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 ...
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0answers
120 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. ...
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3answers
87 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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1answer
112 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 ...
0
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1answer
68 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) ...
4
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4answers
3k views

How to open/display and extract NetCDF files info?

I am working with NetCDF files using R & Matlab and I would like to know if the GIS community is using them. I know that ArcGIS can open & display, however most of the times the results are ...
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1answer
56 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?
3
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1answer
87 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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0answers
121 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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0answers
106 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. ...
0
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1answer
70 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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4answers
2k 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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1answer
61 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 ...
0
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1answer
46 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 ...
0
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1answer
16 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 ...
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1answer
63 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 ...