Skip to main content

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.

564 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
12 votes
1 answer
831 views

Calculate volume of space defined by multiple overlapping 3D polygons

I have thousands of 3D polygons scattered in space but they mostly overlap with many of their neighbors in big extent. Is there any way how to compute volume they define effectively? I would love to ...
vildead's user avatar
  • 231
11 votes
2 answers
2k views

QGIS GRASS Processing Not Working on MacOS?

Recently upgraded to QGIS3 (3.0.2) for MacOS (High Sierra) and encountered GRASS (7.2.2) issues. Tried adding a custom variable and now when running GRASS algorithms (e.g. r.reclass) I get the ...
Gidget1's user avatar
  • 111
9 votes
1 answer
1k views

GRASS v.clean tool in QGIS gives empty output

I am trying to run v.clean in QGIS 3.10.7. I have a 2D LineString dataset saved in GPKG format and I want to run v.clean to clean up some messy topology. But whenever I run it, I get the same result - ...
wfgeo's user avatar
  • 3,598
7 votes
0 answers
1k views

QGIS cannot open output layers

I have problem with QGIS 2.0.1. Everytime I run tool from SAGA or GRASS, I get exactly the same error, for example: Oooops! The following output layers could not be open Channel Network: /tmp/...
Ondrej Berka's user avatar
6 votes
1 answer
1k views

Dealing with no-data values in raster calculator of QGIS

I am trying to patch two rasters with raster calculator but I am not finding the way to work with no-data values. Lager@1 has some information I need as first option, this has as no-data -9999 (...
Marco's user avatar
  • 3,240
6 votes
0 answers
567 views

How to load/enable r.stream.distance and r.lfp in QGIS 3.6.1 with GRASS 7.6.1 (Windows 10)?

I am new to QGIS and GRASS. I would like to use r.lfp in QGIS with GRASS. So far I installed addons extensions r.stream.distance and r.lfp in GRASS (Settings/Addons extension/Install extension from ...
Schop's user avatar
  • 61
6 votes
0 answers
566 views

Running v.clean tool in QGIS Python Console

How to use v.clean GRASS processing tool for break in QGIS from Python QGIS Console.I have tried using below command: processing.runandload('grass:v.clean', layer,\ 0,0.100000,'8132391.27018,8134827....
Ahsan Mukhtar's user avatar
6 votes
0 answers
271 views

Activating GRASS utilities in QGIS Processing toolbox via text descriptors

This is a new follow-on question from this one. Following the documentation outlined in the answer, it is fairly easy to set up a descriptor text file for standard utilities that exist but aren't in ...
MappaGnosis's user avatar
  • 33.9k
5 votes
0 answers
106 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
  • 163
5 votes
1 answer
1k views

r.viewshed Raster map not found

I wanted to test the r.viewshed module from grass via the Toolbox in QGis. But no File is generated. This is the log output: Algorithm r.viewshed - Computes the viewshed of a point on an elevation ...
M F's user avatar
  • 271
5 votes
0 answers
2k views

Using GRASS GIS/QGIS to georeference TIFFs in 3D space, vertically?

I am a geophysicist working for a small shallow surface geophysics firm. We create 2D slices of the ground showing data collected from various surveys. These are generally cross sections (TIFFs) of ...
Toby Child's user avatar
4 votes
0 answers
1k views

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 ...
kaj.n's user avatar
  • 79
4 votes
0 answers
789 views

Installing a GRASS addon in QGIS

I am trying to use the GRASS addon r.vector.ruggedness in QGIS, but it is not available. Then, I downloaded GRASS directly and there it is possible to download the addon that I want. Nevertheless, I ...
Jose Diaz Ramos's user avatar
4 votes
1 answer
359 views

Error: Algorithm not found using grassprovider in PyQGIS standalone script

With QGIS 3.22 the GRASS algorithms got its own provider (grassprovider.Grass7AlgorithmProvider) and are no more part of processing.algs. Knowing this, in a standalone pyqgis-script I am trying to add ...
user104475's user avatar
4 votes
0 answers
275 views

r.to.vect is not responding in QGIS GRASS

NLCD data entered for half of Illinois, all of Michigan and Wisconsin, plus additional along borders. Used r.neighbors to simplify, then r.to.vect with "smooth corners" feature selected. Got ...
Fiddlerman's user avatar
4 votes
0 answers
48 views

What does the blocking option do in GRASS r.watershed?

What does the blocking option do to the r.watershed program in grass? According to the manual, it should stop water from being routed past that location, but it appears to have no effect. I'm trying ...
mankoff's user avatar
  • 1,622
4 votes
0 answers
2k 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 Java)....
Steven Kay's user avatar
  • 20.5k
4 votes
0 answers
285 views

Drawing "proportional" buffer using QGIS or GRASS?

I'm working on aquatic vegetation and have a shapefile representing floating vegetation in a lake. By some studies, we know that submerged vegetation extends for a certain extension based on floating ...
grouchopower's user avatar
4 votes
0 answers
400 views

How to build a GRASS network with node IDs from the line dataset?

I have a dataset of street network links (line geometries). Each network link has a link id, start node id, and end node id attribute. I want to use this network in GRASS, so after importing the lines,...
underdark's user avatar
  • 84.3k
4 votes
0 answers
906 views

Error when using r.watershed in QGIS 2.10.1 with Grass

I am running r.watershed within QGIS processing the I get the error below. I draw your attention to: GRASS_INFO_WARNING(2205,1): Subprocess failed with exit code 256 GRASS_INFO_END(2205,1) Does ...
Vitor Pina Silva's user avatar
4 votes
0 answers
595 views

Option for 360 degree movie embedded in Open Source GIS software?

Is there any Open Source GIS software available to embed 360 degree movies with the map? For a COTS example, there is the Active Link Vision (ALV) extension for ArcGIS from IWANE.
hamizah's user avatar
  • 41
4 votes
0 answers
848 views

Problem loading output layer QGIS

Every time I run operations with temporary file output from the graphical modeler, I get the following error message: Oooops! The following output layers could not be open CLIP: C:\Users\Amine\...
user32882's user avatar
  • 3,544
4 votes
0 answers
914 views

How to install grass addons when offline?

Can anyone tell me how can I install GRASS (v.7) addons on a windows PC when offline? I manually downloaded the files from http://svn.osgeo.org/grass/grass-addons/grass7/ and copied: - the .py file ...
mic_cord's user avatar
  • 499
3 votes
0 answers
698 views

Resample() function in R's terra package and the r.resamp.interp module in GRASS GIS yield such different rasters

Comparing the results from the resample() function in R's terra package (version 1.7-29), and the r.resamp.interp GRASS GIS module (version 8.2), I find differences in how they apply bilinear ...
Eden's user avatar
  • 131
3 votes
0 answers
113 views

Any advice on how to use r.stats in QGIS

I am trying to run r.stats in QGIS to get all unique combinations of data values from 2 raster layers. The process runs, outputs an HTML file, and does not throw any errors. However the files are ...
QuestGIS's user avatar
3 votes
0 answers
296 views

Network analysis in QGIS with nodes at start and end point

I have a dataset form a national agency with a topologically correct road-network. However, I have a problem when applying network analysis within QGIS to the dataset. I have tried both the native ...
ConcreteJungle's user avatar
3 votes
0 answers
153 views

QGIS 3.12.3: V.to.3d: Number of centroids exceeds number of areas

QGIS.3.12.3 | CRS = WGS 84 | Grass downloaded Making a habitat survey map 3d using height values stored in attribute using v.to.3d. Parameters Name of vector map: Habitat layer Input feature type: 4 ...
Jade's user avatar
  • 61
3 votes
0 answers
184 views

How does grass r.viewshed take into account the Earth curvature?

Up to now I always had to do such analysis in a local Cartesian Coordinate System and on relatively small datasets, but today, I want to compute a viewshed analysis on a large raster DEM which is ...
swiss_knight's user avatar
  • 10.5k
3 votes
0 answers
202 views

CalledModuleError: Module run None g.gisenv -n ended with error

I am trying to use r.horizon GRASS module(version GRASS 7.8) in Python script. But I couldn't able to access the grass modules. Everytime, I am getting the following error. File "C:\OSGEO4~1\apps\...
bs karthik reddy's user avatar
3 votes
1 answer
336 views

Route optimization with QGIS

I need to optimize the routes of a collection vehicle working with QGIS. To do this I have a network layer and another with the collection points, both of then in a geopackage. What I need is a new ...
Raúl Casado's user avatar
  • 1,079
3 votes
0 answers
57 views

Line along points with no continous ID and creation date/time

I have a huge points file. The points are along a route network. I would like to build lines by going from point to point - but there is no chronology given! The "ID"s seams to be chaotic ...
MartinMap's user avatar
  • 8,338
3 votes
0 answers
151 views

GRASS 7 problem

I am working with QGIS 3.8.3. I want to split my lines into intersections and for this, I tried to use the command v.clean in GRASS - Processing Toolbox. However, an error msg appears: "This ...
Tatiana's user avatar
  • 31
3 votes
0 answers
1k views

Raster map not found error with r.fill.dir

I am new the GIS world and I am having trouble with generating depressionless DEM from lidar elevation data. I am using GRASS 7.6.1 and QGIS 3.4.12. I have used r.fill.dir successfully on a ...
Andy's user avatar
  • 39
3 votes
0 answers
165 views

Problems importing raster to GRASS from QGIS (error: Datum ETRS89)

When I try to import raster from QGIS to GRASS with r.in.gdal.qgis an error of projection appears. Raster is in EPSG::25831 - ETRS897UTM zone 31N and mapset is supposed to be defined with the same. ...
Blanca's user avatar
  • 31
3 votes
0 answers
109 views

GRASS GIS Segmentation issue on UAV image

I tried i.segment to perform segmentation on a part of UAV orthophoto image, but this always results in stripe-like rectangle segments which I do not expect. Could anyone figure out what happens? ...
Otsuka Haruna's user avatar
3 votes
0 answers
200 views

Using v.net.flow in QGIS/GRASS GIS?

When I try to use the v.net.flow tool in QGIS, the output datasets have a value of 0 for every feature in the flow column. Almost every other v.net tool works, such as v.net.steiner and v.net.distance....
Alex's user avatar
  • 187
3 votes
0 answers
1k views

Convert NetCDF(.nc) (TROPOMI Sentinel-5p) to GeoTIFF (GDAL, GRASS)

I tried converting NetCDF (Sentinel-5p) file to GeoTIFF file but I'm getting: D:\>gdalinfo 20181119T121048.nc Warning 1: Recode from UTF-8 to CP_ACP failed with the error: "Invalid argument". ...
Stefi2019's user avatar
3 votes
0 answers
1k views

Clip raster by mask layer not working in QGIS 3.4.2?

I've been successfully using QGIS 2.18.21 to "clip raster by mask layer" and then run v.rast.stats. However recently v.rast.stats has stopped working in QGIS 2.18.1. The log does not show an error, it ...
user121423's user avatar
3 votes
0 answers
297 views

Convert polygons to lines ignoring redundant vertices in QGIS

Provided the following Polygons layer with 6 polygons (see image below), I would like to calculate each line's segment's angle (amongst other things), so I should convert those six polygons into lines,...
ccamara's user avatar
  • 902
3 votes
0 answers
271 views

r.stream.basin in qgis

I am trying to generate subbasin with provided multiple outlets points by using r.stream.basin. I have install r.stream.basin addon in grass but it does not appear in qgis. Is there any ways to use ...
bikuser's user avatar
  • 177
3 votes
0 answers
74 views

GRASS GIS Error Flags

I am attempting to run a GRASS command from the terminal and eventually a bash script, in which it links rasters in a folder to the Mapset previously defined. I was able to successfully create the ...
TornadoEric's user avatar
3 votes
0 answers
261 views

QGIS 2.18.17: python warning missing init

Every time I open QGIS 2.18.17, I get the following python warning in the protocol window: 2018-03-02T12:30:52 1 warning:C:/PROGRA~1/QGIS2~1.18/apps/qgis-ltr/./python\qgis\utils.py:607: ...
applebrown's user avatar
3 votes
0 answers
105 views

Checking and enforcing downstream Z constraint for synthetic streams?

Assume I've delineated planar (X, Y) stream breaklines to use them for enforcement of bare ground DEM derivation from high density lidar data. The stream features are in a Z and M enabled polyline ...
Ricardo LT's user avatar
3 votes
0 answers
222 views

How to show Vector Layer created by v.clean GRASS tool in QGIS

I have created vector layer using GRASS tool v.snap, which resulted in a vector layer as output. I want to display the vector layer in QGIS. How can i view the vector layer created by snap tool in ...
Ahsan Mukhtar's user avatar
3 votes
0 answers
228 views

Making DTM from contour vectors in QGIS?

I have been using QGIS (2.18.0) for 6 months and now need to make a DEM from contour vectors. From my reading, I know I have to use GRASS. I am in the process of using this tutorial to achieve that ...
Ruth's user avatar
  • 103
3 votes
0 answers
82 views

QGIS - Layer missing polygons after pointsfile transformation

I'm using pointsfile transformation in QGIS for the georeferentiation of my layers. After the transformation the result some times has polygons missing like here: Why is this happening? How do I ...
dari1495's user avatar
3 votes
0 answers
795 views

GRASS 7 commands in PyQGIS without results (QGIS 2.18)

I have tried to run different GRASS commands as part of a PyQGIS script in QGIS 2.18 and 2.14, without obtaining any result, e.g. for the following code: # Open raster fileInfo = QFileInfo(raster) ...
Sophie Crommelinck's user avatar
3 votes
0 answers
221 views

How to accelerate v.generalize on massive vector data?

I have a big problem with my vector dataset (more than 1 million entities) and v.generalize in grass 7.0.5 and 6.4 (64 bits for both). I try to use Douglas method on this dataset but it is very very ...
D.Dallery's user avatar
3 votes
0 answers
377 views

GRASS v.net.iso does not include all lines

I want to define catchment area for bus stops in small city. As a result of v.net.iso in QGIS with GRASS I don't get all highways in that city. Here are my steps: importing above layers into GRASS ...
blackowhite's user avatar
3 votes
0 answers
290 views

r.sun from QGIS toolbox doesn't give realistic value about the hours of insolation

I have a problem with the GRASS module r.sun when I run it in QGIS. I would calculate the hours of insolation in a specific site during a specific day. When I ran the algorithm "r.sun" from GRASS, it ...
Pietro's user avatar
  • 31

1
2 3 4 5
12