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.

learn more… | top users | synonyms

0
votes
0answers
3 views

How to solve “features were not reachable” warning message using v.net.distance in GRASS

I'm using GRASS 7.0.4 under Linuxmint 17.1 KDE. I need to build a raster with the shortest distance from every pixel to a city following a road. I have two shape files, the city (point) and the road ...
3
votes
1answer
122 views

GRASS via Processing Toolbox doesn't work in QGIS 2.8.3 on Mac?

I am quite new to QGIS and working with the external applications such as GRASS. When trying to launch a GRASS tool from the processing toolbox I get the following error: Missing dependency. This ...
6
votes
1answer
359 views

Using GRASS algorithms in Sextante under ArcGIS Desktop?

Sextante for ArcGIS comes with SAGA modules. I know that I can use GRASS algorithms in Sextante under gvSIG. But how can I use GRASS algorithms in Sextante under ArcGIS Desktop? I tried to look ...
0
votes
1answer
17 views

Error operating on file using grass

from grass.pygrass.modules.shortcuts import raster as r gscript.run_command('g.region', ...
2
votes
1answer
639 views

Visualizing a LiDAR point cloud in 3D with GRASS?

I'm new with QGIS and GRASS so I'm sorry if there is a straightforward answer for this question but I can't seem to get it done. I've imported a point cloud into QGIS from a datafile. Now I'd like to ...
3
votes
1answer
92 views

Changing 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 ...
1
vote
0answers
9 views

Exporting multiple layers to single dxf file using Grass GIS?

I'm very new to Grass GIS. I need to export multiple vector layers into a single dxf file (required in order to import into another application). However, I can't see a way of selecting more than ...
2
votes
1answer
19 views

GRASS 7 raster map calculator

I am new to GRASS and am trying to use it because I can't afford the Spatial Analyst extension in ArcGIS. I am trying to remove all of the values in a NDVI raster less than some value to exclude ...
1
vote
0answers
15 views

Neighborhood analyses with GRASS/QGIS using ASTER GDEM

I have a problem related with this question (Old question without answer: R.Neighbors with large neighborhoods?). Basically, I want to estimate roughness of a given area, for which I was using QGIS, ...
5
votes
3answers
151 views

Smoothing method for big polygons

I'm looking for an alternative to 'snakes method' for smoothing very big polygons, which I created from SRTM elevation datasets. The problem is that the smoothing is getting stuck after a while with ...
0
votes
1answer
18 views

r.patch results in a blank map in GRASS

I have a collection of tiles downloaded from the EDINA Digimap service, in asc format. I imported these into GRASS using the r.in.gdal function, and they appear in the display screen as expected. I ...
1
vote
1answer
42 views

How to merge adjacent polygons with no common attributes in GRASS?

Many topics are talking about merging polygons based on their common attributes, but few (or none) give a real answer to location-based merging problem. Explanation. Here is a fraction of the base ...
2
votes
1answer
137 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. ...
0
votes
1answer
67 views

R equivalent of GRASS r.grow?

What is a good R equivalent of the GRASS function r.grow? The closest I've been able to find is the script suggested by whuber in response to Creating randomly shaped clumps of cells in a raster from ...
2
votes
1answer
30 views

QGIS - best fit to the sectoral terrain (SRTM 30m resolution data)

i need a help to find out the Slope of "best fit to the sectoral terrain". here is in details about the area of calculation. we have a reference point, from the reference point our sectoral area ...
5
votes
6answers
3k views

How to pansharpen LANDSAT 8 in GRASS?

Having used QGIS for quite some time for mapping, I was 'forced' to dig into GRASS as pansharpening is not directly executable in QGIS. After understanding more or less the structure, I did some ...
1
vote
0answers
32 views

GRASS gis: treating certain cells as starting points in mapcalc

I am attempting to calculate the vertical height from horizontal of every point on a slope. I want to use stream beds (the lowest points in my DEM) as my starting spot, with the horizontal plane ...
1
vote
1answer
35 views

Question about Using r.mapcalculator in Python console

According to the following conversation: Using r.mapcalculator in Python console? I tried: ##NoData Background=name ##RASTERLAYER_BAND=raster ##nodatabackground=output raster import processing ext ...
1
vote
1answer
194 views

Using r.mapcalculator in Python console?

I'm trying to use the r.mapcalculator algorithim in a python script, but I'm having problems in using the r.mapcalculator to tranform a raster layer with float values into integers. Using the ...
3
votes
1answer
39 views

GRASS r.reclass QGIS 2.14. error: “the following layers were not correctly generated”

I am getting a strange error message when running the GRASS r.reclass algorithm. The error states that: "The following layers were not correctly generated *reclassified You can check the ...
0
votes
0answers
31 views

n-dimensional visualization software

I am using Grass 7.04 standalone. I have made a 3d view of dem raster. How can I have a high resolution image file of it to work with photoshop? It seems that the only tool to have it is Nviz but it ...
1
vote
1answer
13 views

How to open .jp2 with GRASS 7.0.3

Does anyone know if I can use Grass to open a .jp2 image file? I am aiming to do some image classification on the image and when I try to import the image into the program a stream of errors comes up ...
0
votes
0answers
7 views

plotting a proportional sized snowfall fall pin ( also the numerical number) for 150 kal local ng positions on a us map

just starting to learn Grass. Need to learn how to have a usa outline map. (Is this spearfish?) On the map place pins ( for a given latitude and longitude) proportional in height for annual ...
1
vote
2answers
252 views

How to 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
votes
1answer
278 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
votes
1answer
261 views

How do I open GRASS layers in QGIS

I'm quite a newbie to QGIS and GRASS.. I have installed QGIS 2.10.1 with GRASS 6.4.3 on my Windows 7 laptop and wish to open GRASS layers in QGIS. If I got it right, you can use the QGIS built-in ...
3
votes
1answer
107 views

QGIS GRASS raster to GeoTiff

First of all: Windows 8.1 QGIS 2.8.2 Wien 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 now what I want to do ...
0
votes
0answers
18 views

Problem with i.landsat.acca on GRASS

I have a problem with my Landsat Tree Cover Continuous Field. The images are fully of clouds and shadows, so unreadable. The problem is the following: when I try to use i.landsat.acca to remove ...
1
vote
2answers
25 views

Error installing addons in GRASS 7.0.2: File is not a zip file?

When I attempt to install an addon in GRASS Setting->Install Extension from Addons and select the addon i want from the list (r.stream.order) i get the following error: "ERROR: File is not a zip file: ...
1
vote
0answers
66 views

Is this error “invalid context…fatal error” due to GRASS GIS bug or the system?

Copy of error message that appears in the terminal (Macbook Pro, OS X 10.9.5): MacBook-Pro.local Python[2653] :CGContextRestoreGState: invalid context 0x0. This is a serious error. This ...
0
votes
1answer
26 views

How to calculate stream order in GRASS 7.0.2?

I would like to calculate Strahler's and other stream hierarchy from my input raster but I am not sure how. This manual suggests tat I should use r.stream.order command, however in version 7.0.2 ...
2
votes
1answer
435 views

How to extract percentage of land cover from a raster according to multiple shapefiles?

I have a raster map that represents land cover of a region, and different shapefiles (total 120) in the same region. I want to know the percentage of every land cover for each shapefile. For example, ...
5
votes
2answers
1k 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 ...
1
vote
0answers
15 views

GRASS 7.0.3 - Script to automate multiple simulations?

I am working in GRASS 7.0.3 and want to conduct a complex analysis of Least-Cost Paths of the many-to-many type. Specifically, I do have my elevation raster (ASTER DEM) and point data of 300 random ...
1
vote
1answer
58 views

Positive Topographic Openness - do any FOSS tools (other than SAGA) provide this?

I'm looking for a FOSS GIS tool to provide Positive Topographic Openness on 32-bit Ubuntu. (which rules out ArcGIS) Normally I use SAGA GIS for this, but my Ubuntu setup is a bit messed-up after a ...
0
votes
1answer
16 views

R.patch creating enormous file size

I'm using r.patch (within QGIS, GRASS 7) to patch two Float32 rasters both of which have a respective filesize of under 200MB. When I save the memory layer raster created by the r.patch function, the ...
0
votes
0answers
14 views

Grass Gis i.atcorr for Aerial data

Can Grass GIS i.atcorr module be customized for Aerial sensor? Attempted for Aerial sensor which has altitude of 13km. but module is failed .if the satellite altitude is changed to 100 km, module is ...
1
vote
0answers
22 views

Raster Precision QGIS

I am using r.patch extension in QGIS to join a number of LiDAR tiles, some of which overlap hence i am carrying out this task before utilising in a hydraulic model. R.Patch works fine, however the ...
0
votes
1answer
179 views

How does i.fusion.brovey in Grass 6.4.3 work?

I'm using Grass 6.4.3 in Linuxmint 16. I don't have a very big problem but I'm trying to understand what is Grass doing, if I'm applying the process correctly and if there is something wrong with my ...
1
vote
0answers
40 views

OS X Yosemite: copy / paste into shell GRASS 6.4.4. within QGIS 2.14.0

I want to know How to copy/paste into GRASS 6.4.4. shell within QGIS 2.14.0. I'm working with OS X Yosemite and the right mouse button doesn't work neither shortcut (cmd+c/cmd+v)
1
vote
2answers
29 views

How to export vector file in GrassGIS to QGIS

I am using GrassGIS to analyze watershed. I created a stream vector extracted from raster elevation data, how to extract the stream vector file so I can open it using QGIS?
1
vote
1answer
196 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?
0
votes
1answer
221 views

grass - add on problem

I can't install the addon in grass 6.4.3 to my linux mint. i've already installed the SVN and than it says: GRASS 6.4.3 (fabian_idrisi):~ > g.extension r.fuzzy Fetching from GRASS-Addons SVN (be ...
2
votes
0answers
25 views

How do I merge a point attribute table to a polygon attribute table in QGIS or GRASS?

I have a point layer containing the following data: I want the following polygon areas to be added to the point attribute table as all the points occur inside the various features of the polygon ...
3
votes
1answer
63 views

GRASS r.in.lidar problem on Windows 10: 'no such file or directory'

I'm having problems to load .las files into Grass GIS 7.0.3 for Windows 10. I use the module r.in.lidar but I get the following message: What can I do? How can I solve the problem?
2
votes
1answer
219 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 ...
2
votes
2answers
187 views

QGIS 2.14.1 Processing Toolbox GRASS 7 .NVIZ Not working

I have a problem with the command GRASS 7 .nviz in QGIS 2.14.1 installed through QGIS-OSGeo4W-2.14.1-1-Setup-x86_64.exe.md5sum all GRASS commands work exept .nviz / nviz7 images: I test with ...
2
votes
2answers
122 views

Where is the nviz tool in qgis 2.14 with GRASS 7.0.3?

I hope Im not blind but I looked in the grass tools (modules) and qgis plugins but couldnt find it. When i try to run nviz from GRASS the whole programme chrashes just before concluding. Its a ...
1
vote
1answer
45 views

How to design a flood with water elevation on a specific point?

Actually I have to know the flooding area caused by a rise of the water level due to the implementation of a dam. So I would like to know if there is an extension or any tool in QGIS or GRASS which ...
4
votes
1answer
244 views

Cannot locate GRASS plugin in QGIS 2.14.1 on Linux

I am trying to load the GRASS plugin in QGIS but it is not shown in the plugin manager (no matter if I turn on experimental and deprecated plugins). Under processing / options / providers GRASS GIS 7 ...