Questions tagged [grass-gis]
GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) specialized in handling raster, topological vector, image processing, and graphic data. GRASS GIS is a high performance analytical GIS and remote sensing with focus on modularity. Users can process both day-to-day data as well as massive time series.
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Using v.distance to classify points far from overlapping polygons always return the same set of polygons
I have two vector layers with the distribution of an animal species. EDIT: I'm showing how the maps look in QGIS, but I'm working in GRASS GIS. First dataset:
Second dataset:
As you can see, these ...
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How to update string column of a shapefile GRASS GIS
I'm relatively new in GRASS GIS and I want to update a column of a shapefile.
I use GRASS GIS (version 7.8.6 on Ubuntu 20.04 .4 LTS), not the GRASS extension in QGIS.
I'm workin on a shapefile. In ...
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QGIS grass imports vector line data as points, not vector lines
I am very new to QGIS and Grass. I am trying to create a dxf file with height data using Grass 7 as per this youtube video. (1:35 mark)
My contour data and Qgis file is uploaded here. When I go to ...
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Problems with GRASS tools in QGIS 3.28 LTR
I've tried to use GRASS tools, like v.clean and v.buffer, and only got those error messages:
QGIS version: 3.28.4-Firenze
QGIS code revision: fd0fb72ab3
Qt version: 5.15.3
Python version: 3.9.5
GDAL ...
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Different Coordinate system in r.water.outlet
I'm trying to use the r.water.outlet when selecting the coordinate from the map it changes the coordinate system as in the picture. I make sure all the layers and the project have the same coordinate ...
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GRASS init error
I have installed the GRASS 7.8.7 plugin on QGIS. However, when it loads up the GRASS drop down is available but key functions such as New Mapset etc. are greyed out.
I also get the following error ...
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Select a specific band in GRASS (QGIS)
In GDAL you can use flags like
-b 1 -b 2
to select individual bands from a multiband raster
In Arc you can sometimes use "...\whatever.tif\Band_1" to select an individual band
Can you do ...
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Geometry error in large dataset
I have a large shapefile that I'm working on, containing more than 555.000 polygons, that represents the area covered by a 5G network. I have to extract areas that are not covered by a 5G network ...
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why is my input-Pixel in "r.resamp.filter" not always the center-pixel of the output?
I struggle to understand the mechanics from r.resamp.filter. I create a raster in the projection EPSG 2056. with cell-size 1 around an arbitrary origin (here:
Extent -8.1370000000000005,983....
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How to create a wind map from wrfout in GRASS GIS
I would like to create a wind direction map in GRASS GIS using wind U-velocity and V-velocity, which are outputs from the weather model WRF.
I tried to create a wind direction map with the command d....
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Calculating percentage of small grids in coarse grid (fill ratio)
I am doing an analysis of two rasters in grassgis.
I am trying to determine the number of small grids (resolution=800×800) that are included (overlapped?) in the coarse grid (resolution=249×229) when ...
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How to use v.net.path algorithm on QGIS?
I want to use the v.net.path (see grass documentation) from the QGIS processing toolbox. However, I do not know what the format of the input parameters is. The required parameters are:
Input vector ...
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Set elevation of 2.0 meter above cells when running grass r.horizon second method
I am using the algorithm r.horizon second method, it takes a raster, start azimuth angle, end, step size etc. and calculate the horizon altitude angles for each pixel, each azimuth has own layer.
From ...
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Problem running QGIS r.horizon command in PowerShell
I would to run this command in images below via CMD also without opening QGIS GUI on Windows 10
I added "C:\Program Files\QGIS 3.28.2\bin\qgis_process-qgis.bat" to PATH then run my command ...
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Miminum values of a raster change when applying r.resample
I am trying to aggregate a raster of a bioclimatic variable (can be downloaded here: https://envicloud.wsl.ch/#/?prefix=chelsa%2Fchelsa_V2%2FGLOBAL%2F > Climatologies > 1981-2010 > bio/ > ...
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How to interpret the numbers in the left column?
I ran r.report on a raster file and got this result. I cannot interpret the numbers in the left column. I'm still a beginner and I don't quite understand why the left column doesn't say land cover ...
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Create a location for GRASS GIS command without GUI is not understood by GRASS from bash
On CentOs 7.. I installed GRASS by
yum install grass
So, using this great tutorial: https://xycarto.com/2020/05/03/basic-grass-gis-with-bash/ I try to get started with GRASS.
I made a folder ...
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Looping GRASS "v.extract" in python
I have a multipolygon shapefile representing different cities. I am trying to loop the "v.extract" GRASS command through the different polygons via the Python interface.
This is the code I ...
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Export raster band to greyscale image in GRASS GIS
I'm trying to output the ARVI band of an image to a JPEG from GRASS GIS. I need the image to be the same resolution, as I it will be used for creating label data for a ML model in LabelStudio.
I ...
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Viewing Errors from in pygrass
I am running using grass-session to run grass within a python environment on some short lived AWS servers. I am getting some errors from running r.sim.water, but I can't see what they are because they ...
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GRASS addon r.tg.grom throwing a Python error
I'm trying to get this addon to run in GRASS to calculate Topographic Grain for my DEM. I've managed to get it installed and functional on GRASS 7.6 on macOS 12.2.1, but after inputting my parameters ...
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GRASS processing fails with osgeo4w instalation of QGIS 3.22 LTR
I've searched and tried many potential solutions, unsuccessfully:
I uninstalled my previous QGIS (3.16 from standalone .msi installer, everything was working well) and installed QGIS 3.22 (LTR) with ...
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GRASS i.rotate function not appearing - any idea's why?
I want to look at rotating a layer using GRASS' i.rotate tool, but it is not showing in the toolbox. Am I looking in the wrong place?
Update
I have run the i.rotate tool in GRASS independently but it ...
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Convert smoothened contour in QGIS ( vector) to raster for use in HECRAS
I have generated contours in QGIS using point data (AutoCAD file) and I had to also smoothen the contours and remove noises (smaller contours) from the contour generated. I need to get this contour ...
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QGIS: global solar irradiance calculation and analysis
I am working on a climate change project where I want to have a map showing the average temperature per month at a local scale. I want to use the following data: average temperature from weather ...
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1
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64
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Error using Grass v.net.centrality
I have a network downloaded from Open Street Maps on which I want to run the Grass v.net.centrality tool. I've tried everything I can think of, including reinstalling QGIS (I've tried multiple ...
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V.NET.SALESMAN problem filling in dialog box parameters
I have a problem with the process of the algorithm "V.NET.SALESMAN" that surely is simple but I can't do it. I have read Grass’ documentation and similar posts here in Stack Exchange but in ...
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GRASS GIS 8.2 fails on startup
I just installed GRASS GIS 8.2.0 with the standalone installer, but I'm having issues at startup. Instead of reaching the main window I end up with the command window shown below.
Any ideas on what ...
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Both GRASS and SAGA fails on QGIS 3.28
After having trouble with GRASS and SAGA on my Windows laptop, I have just reinstalled QGIS but it has not solved anything. Hopefully I'm missing something obvious, but I cannot for the world figure ...
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Enabling GRASS in Processing Toolbox of QGIS 3.28.2.0
I installed QGIS 3.28.2.0 (Release candidate) via Network installer on Windows 10.
I am missing GRASS in the Processing Toolbox. How to enable this?
GRASS 7.8 is installed (There is no separate start ...
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Convert a layer from WGS 84 to WGS 84 / Pseudo-Mercator during GRASS import
I have a bash script that does the following:
export PATH=$PATH:/usr/local/grass/bin
GRASSDATA=/output/grassdata && \
MAPSET=PERMANENT && \
MAP=outputAmtrakMap && \
rm -rf $...
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Overlapping lines or polygon in GRASS GIS 3D
I have a shapefile GIS layer with several overlapping paths. They consist of geodetics/shortest path calculations from several origins to one destination. I want to visualise these paths as either as ...
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v.in.ogr does not provide any error information
I am using the mundialis/grass-py3-pdal:8.2.0-alpine docker image to run GRASS. I run the following from the bash command line (inside the container):
/usr/local/grass/bin/v.in.ogr input=/path/to/...
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Fixing errors installing QGIS on Ubuntu
I’m trying to install the latest QGIS stable version 3.26.x on my ubuntu 20.04 system. I’m following these instructions at qgis.org, starting at “Here you will simply install the latest stable QGIS“.
...
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QGIS modeler not finding GRASS
I have problem to create simply process in QGIS modeler.
I got error message:
Algorithm is not available
Why its not available, same GRASS algorithm works in QGIS desktop?
What is that red box in ...
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Merge two or more overlayed "Drainage Direction" rasters calculated with r.watershed command
I have a big raster and I need to calculate catchment areas with GRASS command (r.watershed, r.water.outlet) but I can't process it due to its weight.
In order to solve that problem I've divided the ...
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111
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Which is the correct way to write commands in GRASS GIS on Windows?
I learnt how to use GRASS GIS from an Ubuntu machine, directly using the command line. I wrote my commands in a text editor (e.g., Notepad++), and I just copied and pasted the lines I was interested ...
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GRASS r.stats.zonal help
I am following this tutorial but redoing it with more current data:
https://ecodiv.earth/TutorialsNotes/deerdensities/results.html
I am recieving the error: ERROR: The base map must be an integer (...
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Improve the quality for a raster PNG in Georefrencing QGIS
I imported a raster .png file (convert from .svg) in Georeferencer, the resolution is acceptable but after the geo referenced layer is placed on top of the map, it becomes a blur.
I tried this GRASS ...
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GRASS GIS in OSGeo Live - cannot add extension
I use GRASS GIS in OSGeoLive v14 on Ubuntu in virtual machine (Oracle Virtual Box). When I try add any extension, it is giving me a FileNotFoundError: [Errno 2] No such file or directory: 'svn'.
I ...
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GRASS init error: GRASS was not found in 'INVALID/S/qgis-deps-0.9/stage/grass78' (GISBASE), provider and plugin will not work
I have downloaded QGIS 3.26.3 from https://www.qgis.org/en/site/ and installed it on my Mac M1 Pro running OS 12.6
On launching QGIS I get the following initialization error:
"GRASS init error: ...
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Remove inner boundaries in merged vector layers
I am using QGIS and the GRASS plugin for a watershed analysis where I would like to merge three small natural catchments into a larger one.
I used the 'Merge Vector Layers' function (under the 'Vector'...
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How to calculate proportions of area occupied when one rasters is totally overlapping with another
Suppose I have two rasters (here vectorized for visualizing purposes): yellow (Y) and violet (V).
I want to know the proportion of area each of these rasters occupies compared to the area available. ...
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Where do installed add-on extensions appear in GRASS GUI
I have just started using the GRASS GIS GUI, and went onto settings to install the v.krige add-on extension
It has successfully completed, but I can't find where it is on the GUI to run it?
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395
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QGIS: Resample (upscale) raster using a Gaussian filter
I want to resample a raster from 15m to 460m using a Gaussian filter.
The goal
I am having a coarse image which I want to downscale. I also have a fine resolution band to assist the downscaling. The ...
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How to use Python packages (GeoPandas, rioxarray) inside GRASS Python scripts?
I want to combine the functionality of GRASS GIS with other Python packages such as GeoPandas and rioxarray. My OS is Windows. It is possible to import other standard packages such as numpy and Pandas....
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Issue with GRASS tool r.to.vector
I'm trying to obtain quality vector data from a JPEG raster file of a cadastre area in the Netherlands. I thinned the raster with the GRASS thin tool and also filled it with the fill tool, but when I ...
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GRASS 8.3 not downloading sample data or addons/extensions on Window's 11
I m trying to install addons in GRASS 8.3 and download the sample datasets, but the error message says I m not connected to the internet. I am. The only sample dataset that was downloaded was the ...
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QGIS: QgsProcessingOutputLayerDefinition Error
I'm trying to use v.clean to clean up some gaps in my shapefile. It seems like the processes finish fine but I'm having trouble actually saving the layers.
Execution of <C:\Users\Ben\AppData\Local\...
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2
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88
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Loading and reprojecting .nc file without projection
I am trying to extract some bands from a .nc file. I don't know the file projection (if there is one), thus I created in GRASS GIS a newLocation with no projection (just a XY Cartesian plane) and ...
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