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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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How to import Sentinel 2 data using the command line

I am encountering the following reported error while importing the Sentinel 2 data given by the official website using the command line?1 I doubt if it has anything to do with projection? Can anyone ...
徐志豪's user avatar
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19 views

GRASS r.recode lowest value given no data

I would like to recode a floating point raster using GRASS' r.recode called within a Python function. As rules file for r.recode, I am using a file created by r.quantile with the -r flag. I am using ...
archeo_gis's user avatar
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25 views

r.walk no output band 1: SetColorTable() only supported for Byte or UInt16 bands in TIFF format

I'm trying to use r.walk GRASS algorithm on QGIS 3.28 'Firenze' (Windows) but there is no output with: band 1: SetColorTable() only supported for Byte or UInt16 bands in TIFF format error every time ...
Wojciech Wawręty's user avatar
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1 answer
24 views

r.fill.dir not responding

I have been working on delineation of the Orange river basin in South Africa. Its now one full week trying to fill the DEM file using r.fill.dir in QGIS but it take decades with no response and the ...
Silas's user avatar
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15 views

r.in.xyz (GRASS GIS) not outputting a raster

I have a xyz file points from a lidar dataset and I want to create a raster from it. I'm trying to use r.in.xyz to import it and it seems to be working and it founds 1641751 points, no errors or ...
bona_rivers's user avatar
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1 answer
43 views

GRASS r.viewshed not working with elevation? - PyQGIS

I'm making a QGIS plugin that uses grass:r.viewshed to analyze the area of terrain visible from different points. However, I've noticed, that when using a viewpoint where the elevation between the ...
oliver's user avatar
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Using GRASS GIS addons in QGIS environment

I would like to use r.houghtransform which is an addon to GRASS GIS inside QGIS, because I'm not familiar with GRASS. I have tried to import it with g.extension.manager inside QGIS but it doesn't work ...
Oskar Nyman's user avatar
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54 views

Open source tools to merge categorical raster classes with neighboring class based on area

Given a categorical raster, I'd like filter based on area (ex. number of contiguous pixels) and then: For island groups (no neighbors) that are smaller than the desired area - remove (set to nodata) ...
Brent Edwards's user avatar
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44 views

GRASS GIS from server taking hours to import a shapefile

I have a large shapefile (1GB) with 12k features. It takes 8 minutes to load in R studio (v.4.3.3) using terra package (v.1.7-71), function vect(), on a Windows machine with 32GB of RAM and an Intel(R)...
LT17's user avatar
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Grass GIS vector seem to lost connection to database table, but in file dbln connection exists

After I imported a big vector file and table in sqlite.db was successfully created, there were some operations then I got an error: DBMI-SQLite driver error: Error in sqlite3_prepare(): select * from ...
Nikolay Yasinskiy's user avatar
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GRASS Tools Panel (vers 8.3.1) in QGIS (vers 3.34.4): Filter button does not work

Here is a screenshot of what I am addressing. As you can see if I type any module's name I don't get any result. How can I fix that?
FedeR.90's user avatar
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v.generalize along tile edges

I have a problem with v.generalize and I hope I can find help here. So what I'm trying to do is the following: I have a large number of 1x1 km tiles of rasters that represent traffic areas (roads, ...
Felix_geospatial's user avatar
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1 answer
36 views

Can't find d.rast.edit in my GRASS modules

I'm trying to manually edit a raster by using the GRASS tool d.rast.edit as I've seen it's worked for other users. However, even though I have the rest of the GRASS tools, I can't seem to find the ...
Lucas's user avatar
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27 views

v.clean with rgrass does not work, vector type not found

I'm trying to clean a vector file called network with rgrass library using v.clean. Here's my code: Sys.setenv("GRASS_INSTALLATION"="C:/Program Files/GRASS GIS 8.3/") library(...
Freestyle Season's user avatar
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1 answer
31 views

r.out.gdal exports raster with projection but without extents

Exporting raster with r.out.gdal with PCRaster driver gives two files - .map itself and .xml with projection and colormap. But... I can't find the information about extent. Projection is EPSG:4623 (...
Nikolay Yasinskiy's user avatar
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1 answer
57 views

DCELL cell type is set automatically for raster after r.resamp.interp

After interpolation with r.resamp.interp with bilinear method DCELL cell type is set for raster. When I export it with r.out.gdal I get a precision loss error, as I export it as Float32 (PCRaster ...
Nikolay Yasinskiy's user avatar
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0 answers
38 views

Colour intersecting viewsheds by number of intersects

I'm creating a PyQGIS plugin which utilises the Grass7 r.viewshed algorithm. It creates viewsheds as .tif Layers in the project, using the main raster layer as a Digital Terrain/Elevation Model for ...
oliver's user avatar
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27 views

Why importing QGIS rasters into GRASS Mapset is not working

I am using GQGIS 3.30. I enabled GRASS and Processing Plugins, and pointed them to the right directory. I created a new mapset and location. Then I used the GRASS toolbox "Import raster into ...
Andrea's user avatar
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33 views

Input/Output Warning and uncompression error during v.rast.stats processing

First I use command r.slope.aspect elevation=dem slope=dem_slope format=percent --overwrite to calculate slopes in percent. I get a warning during slope calculation: WARNING: Unable to flush file ...
Nikolay Yasinskiy's user avatar
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1 answer
159 views

GRASS r.horizon returns nonsense

I am trying to calculate the horizon profile from a point on a mountainside, through the appropriate DTM elevation file and the GRASS function r.horizon.height (via QGIS). However, the output looks ...
elevation_modeller's user avatar
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25 views

Different area between Query raster/vector tool and v.to.db

I found a discrepancy between the select GUI tool "Query raster/vector" and v.to.db, and I do not know why. I attached the pictures. First image (image 1) show that the attribute "...
Pablo Sanhueza's user avatar
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85 views

Using v.voronoi.skeleton in Qgis 3.43 with Grass8

In previous QGIS-versions that used Grass7 I designed a model that used v.voronoi.skeleton. But with the upgrade to 3.43, and Grass8, this model will not work anymore. It complaints that grass7:v....
StefanK's user avatar
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Why new v.dissolve procedure generates new database tables and causes an error on adding columns later?

The new v.dissolve procedure includes, as the documentation states, two independent processes: v.reclass and v.extract, being a front end to those. In my case when v.reclass is called it creates a new ...
Nikolay Yasinskiy's user avatar
1 vote
1 answer
51 views

What is the right way to dissolve vector features in GRASS GIS on attribute values of one column summarizing or averaging others?

The line product of v.overlay contains a column with zones number and a stack of other attributes. What I want: Dissolve features (lines) on attribute column that contains zones number. Other ...
Nikolay Yasinskiy's user avatar
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0 answers
34 views

How to get zonal statistics of a vector map by areas from another vector map in GRASS GIS?

I have a map with areas (polygons) and another map with lines for example. Lines have multiple attributes and I want some of them to be summed and written to new columns of my areas map. Each polygon ...
Nikolay Yasinskiy's user avatar
0 votes
0 answers
67 views

How do I calculate albedo in QGIS from a Landsat 8 image downloaded from EarthExplorer

I'm using QGIS and I'm struggling to calculate the albedo from the images. I don't understand how to use GRASS as every time I use it, I get something that doesn't make sense. Sor far, I have ...
GISNewbie2024's user avatar
0 votes
2 answers
78 views

Segment lines by given divider

I a trying to segment lines with specific values that are stored in a field. For example, I need my line 1 which is ~84m long, to be segmented into two segment that are 31m and 53m long. I have a ...
basile's user avatar
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1 answer
43 views

Use v.clean function from GRASS in Jupyter Notebook

I want to automate a process which involves using v.clean tool from GRASS inside a Jupyter Notebook. I've read documentations on how to use Python with GRASS, but it seems impossible to do it or I don'...
Freestyle Season's user avatar
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2 answers
93 views

Fatal Error when trying to download addons for GRASS 8.3.1

I get an error with g.extension r.stream.order: ERROR: Failed to get branch from the Git repository <https://github.com/OSGeo/grass-addons/>. fatal: unable to access 'https://...
Nikolay Yasinskiy's user avatar
0 votes
1 answer
32 views

How can I update a column of a vector layer for reversed selection of features using command line?

Let it be two layers: one with multiple polygons, other with one. The task is: to select features of first layer that intersect with the second, then calculate values of a new column (for example: ...
Nikolay Yasinskiy's user avatar
0 votes
1 answer
53 views

How to resolve "Rscript not found" error when executing r.futures.potential in GRASS GIS?

I'm trying to run a Python simulation script in GRASS GIS 8.3.1 on Windows that utilizes the r.futures module. I get the following error when the r.futures.potential command is reached: ERROR: ...
user22780500's user avatar
1 vote
1 answer
234 views

Cannot install GRASS addons in GRASS 8.2 (Ubuntu jammy)

I am trying to install the r.clip addon in GRASS 8.2 in Ubuntu 22.04.3 LTS (jammy). I installed GRASS 8.2.0-1~jammy0 from https://launchpad.net/~ubuntugis/+archive/ubuntu/ppa and ideally need to use ...
Ernesto561's user avatar
2 votes
1 answer
474 views

PCRaster Tools, GRASS and SAGA installation on QGIS 3.34.2 for MacOS

I have followed the instructions here https://www.youtube.com/watch?v=RaFrXzw7IvI to install PCRaster Tools via conda, which is working. However it appears that all of my previously installed packages ...
Justine's user avatar
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0 answers
20 views

r.mapcalc in GRASS GIS fails to mask rasters

I have a raster binary map (0-1) where 0 represents unsuitable areas (violet) and 1 represents suitable areas (yellow). I want to crop another raster (red) based on this suitability (for several ...
LT17's user avatar
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5 votes
0 answers
107 views

Install GRASS missing addons within QGIS

I'd like to use r.sun.hourly and r.sun.daily from within QGIS but it doesn't seem to be present in GRASS tools. I tried to install it using g.extension in the GRASS shell, but it says I have to run it ...
Louis's user avatar
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1 answer
23 views

r.cross: max number of input map layers?

r.cross serves for combining multiple maps. The current docu (https://grass.osgeo.org/grass83/manuals/r.cross.html) states in section Parameters: Names of 2-30 input raster maps However, further ...
GISmo's user avatar
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1 vote
0 answers
41 views

Running grass7:r.watershed in QGIS gives different results to running identical process in QGIS

a former colleague created a QGIS tool in Python for the Team which creates Flow Routes and TWI (Topographic Wetness Indicator) maps for a selected location. I have run through the code and copied the ...
sar_copp's user avatar
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0 answers
67 views

Hans Der Kwast - Derive Streams and Catchments Model (r.to.vector not outputting file)

I'm using the model created below and following the steps from 17:00 onwards https://youtu.be/ZC0skH4ifsI?list=PLeuKJkIxCDj2Gk0CkcJ-QeviE41aMZd-5&t=1021 I've followed the osgeo4 installation steps ...
Alex's user avatar
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0 votes
0 answers
65 views

Installing old extension using g.extension of GRASS GIS

I am new to GRASS GIS and trying to get this extension I found working. https://gitlab.com/invafish/r.stream.culvert So, it fails to find if I try g.extension g.extension r.stream.culvert url=” https:/...
SunnyD's user avatar
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35 views

QGIS Grass Raster import using r.in.gdal.qgis: 'Layer data source could not be found'

I'm a QGIS learner following the official QGIS Training Manual. I'm on Module 12.1. My problem is that when I try to add a raster layer to GRASS using r.in.gdal.qgis, the resulting layer shows a red ...
JnomiddlenameHoward's user avatar
1 vote
1 answer
41 views

Why stream numbers generated by r.stream.order go one after other, not succeeding

Subwatersheds and streams corresponding form an 2n+1 series, where n=0,1,2... I don't know for what reason, and I also doubt if it works like that in all cases. It's very useful for me as I would like ...
Nikolay Yasinskiy's user avatar
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0 answers
17 views

Is it possible to split a polygon-subwatershed with a gage point without v.overlay?

After creating a clean map of subwatersheds I want to split some where control gages are located. If I try to do this with v.overlay (AND) - clipping subwatersheds previously generated with r.basins ...
Nikolay Yasinskiy's user avatar
0 votes
0 answers
41 views

Using gdal_translate to convert 32-bit raster to byte is black

I have a 32-bit float raster in GRASS. It is a single channel Sentinel 2 raster. I can export to geotiff with r.out.gdal: g.region rast=orthoimage_red r.out.gdal input=orthoimage_red output=...
Jeshua Lacock's user avatar
1 vote
0 answers
82 views

GRASS paths in Python standalone from QGIS install

I am trying to access GRASS from Python (Spyder). I have: Installed via pip install grass-session Started GRASS from OSGEO4W, loaded the mapset and location Started Spyder from Anaconda Tried to ...
william3031's user avatar
1 vote
1 answer
54 views

Creating relation for duplicate lines

I have two datasets with some duplicate lines. I can select the duplicates with GRASS v.select: v.select ainput=map1 binput=map2 output=duplicates operator=equals or QGIS Select by Location: ...
Jeshua Lacock's user avatar
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0 answers
31 views

Exporting .LAS file after using v.lidar.correction

Question I want to use the GRASS GIS LIDAR modules (v.lidar.edgedetection, v.lidar.growing, and v.lidar.correction) to classify points for LAS files. I'm very new to working with databases, and the ...
mozmoz3737's user avatar
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1 answer
55 views

Why is r.grow.distance in GRASS GIS returning a raster with all values = 0?

I'm trying to create a raster map that contains "Euclidean" distances to roads from another raster that contains said roads, by using r.grow.distance in GRASS GIS. The command executes ...
user22780500's user avatar
0 votes
1 answer
34 views

GRASS build polylines based on category/ID (v.net.distance)

I have calculated shortest routes between citywide origin-destination pairs with GRASS and v.net.distance. These routes are segmented, however, and I would like to turn them into polylines based on ...
SPet's user avatar
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1 answer
112 views

Running GRASS GIS from PyCharm

I follow the Working_with_GRASS_without_starting_it_explicitly with GRASS 7.8.8 (2023), but it did not work as intended. The Python line "gs.message" runs, but the line "gs.run_command('...
Pablo Sanhueza's user avatar
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0 answers
41 views

Exporting records with more than 250 characters in a field to GML

I am trying to export OSM vectors to the GML format like: v.out.ogr input=network output=network.gml format=GML I get an error that the field a_other_tags has more than 250 characters: ERROR 1: ...
Jeshua Lacock's user avatar

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