Questions tagged [grass]

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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27 views

GRASS - Calculate 90th percentile of a timeseries dataset

How can I calculate the 90th percentile from a registered timeseries dataset of 30 rasters in GRASS? GRASS timeseries has 2 "statistical" commands which are t.info and t.rast.univar. ...
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1answer
17 views

Problems to execute r.in.lidar

I try to open a Lidar file in GRASS GIS 7.8.5 and 7.9 in a Macintosh computer. However, when I try to open the tool r.in.lidar, it appears: No such file or directory: 'r.in.lidar'.
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21 views

v.net.steiner tool in QGIS not producing output

I have a shapefile of a network of points mostly on roads (a county shapefile from TIGER downloads). I want to find a minimal length tree along the road network that hits all points within 100m of the ...
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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 ...
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20 views

How to limit calculations of r.grow.distance to contiguous cells in raster mask?

I have a layer with rasterized vector polygons (white cells) in a GRASS database. The region is set to the bounding box of the polygons. I also set a raster mask to mask all cells between these ...
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1answer
41 views

QGIS 3.16.5 v.distance returns UnicodeDecodeError

I'm trying to run v.distance on QGIS but get the following message/s: 2021-04-14T17:45:55 CRITICAL Traceback (most recent call last): File "C:/PROGRA~1/QGIS3~1.16/apps/qgis-ltr/./python/...
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0answers
19 views

Using r.houghtransform [GRASS GIS]

I am trying to draw lines that run the length of rows in an orchard. I have a nice binary image that I produced from an optical image (see below). I need to delineate the crop rows with a simple ...
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2answers
24 views

v.surf.idw failling with “Killed” message on GRASS 7.8.2

I have a categorical raster with gaps that I would like to fill using a nearest neighbour interpolation. The r.fill.gaps module does not implement this interpolation method so I am trying a manual ...
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0answers
17 views

Create a .csv of list of number of non null cell from raster in a mapset

How can I create a .csv file (maybe output of a function) of number of non null cells of raster from a given list in GRASS (e.g. rasters could be: myraster#1... myraster#500)? Unfortunately g.list ...
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1answer
17 views

Grass v.dist tool error when measuring distances from line segments to lines

I am using QGIS version 3.18.1-Zürich. I am trying to measure the distance from various lines I created using the intersection tool, but I keep getting this error when using the v.distance tool: ...
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Installing v.stream_order on GRASS 7.8.3 on MacOS

I am trying to install the v.stream.order add on in GRASS and get the following error: ERROR: GRASS Addons <v.stream.order> not found This happens with all of the extensions I have tried to ...
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Parallel lines not showing on my map document (QGIS; v.parallel function)

Weird issue: I am trying to use v.parallel to draw a line parallel to a single line layer I have. It processes without issue, but the parallel line does not appear on the map. The curious thing is ...
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1answer
49 views

Joining attributes from both sides of a line

I have a layer with street segments that I would like to join with a building + population layer. Desired result: The segment contains population data. Nearest neighbor (NNjoin) finds the closest ...
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41 views

Transforming a GRASS formula into a code usable in R

I would like to transform the formula at the botton into a formula for R , as R runs better and fastly with files I have, but I am new with it- For me it is enough even a "literary" ...
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1answer
58 views

Adding height values to map in QGIS

I am facing a couple of issues - I think they are related. Firstly... I am attempting to add height values to my habitat survey map to produce a 3D map in QGIS 3.12.3. I have height values stored in ...
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141 views

QGIS issues on Mac OS Big Sur 11.2 GRASS and SCP issue

I have been having issues with QGIS on my Mac. The current operating system is Big Sur 11.2. The current workaround to the SCP plugin is to revert back to version 6 via these steps: https://...
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1answer
38 views

“ERROR: Unable to load GDAL library” occurs when trying to GRASS functions in QGIS

I'm new to QGIS. I'm using GRASS operations to analyze raster layers and getting ERROR: Unable to load GDAL library in QGIS. Maybe the path is wrong which should point the GRASS operations to GDAL. ...
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1answer
44 views

Creating polygon from perpendicular projection of light on wall on DEM using GRASS

Scenario: I have a DEM a Polyline with elevation, representing a man made barrier like a levee or a giant wall. Polyline will always be on top of DEM. I want to get a polygon that represent all the ...
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1answer
16 views

GRASS: Extend Map Display canvas to full window

This has been a feature of the 7.8 releases, the map canvas in the Map Display does not extend to the full window. The size of the map canvas seems to be hard-coded somehow, no matter the size of the ...
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0answers
24 views

parallel changin region - WIND_OVERRIDE

INTRODUCTION: I have 5000 mammal species and I'm studying Extreme Climate Event impacts on them. I'm now analysing warm spell duration index (WSDI) which is defined as number of days in a year where ...
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29 views

QGIS / GRASS GIS How to make offset / parallel lines with Z values

Please how to make something like v.parallel (GRASS function in QGIS) or offset (QGIS) from 3D line with keeping Z value (with z geometry). My vector 3D line is center of river and i need to make ...
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1answer
15 views

GRASS v.to.rast outputs a bounding box of the geographic region

I'm trying to rasterize a vector layer in GRASS after setting the geographic region to the vector layer extent. I also used v.category to add categories to my vector layer. The command I'm using to ...
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1answer
26 views

v.to.rast command in one shell script with other commands

I am using the latest GRASS Gis and QGis versions. In order for a study project, I have to rasterise a vector layer using v.to.rast. This has to be done in my already existing shell script, in which ...
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0answers
19 views

How do I update a polygon with values from a line in GRASS

I have a line map generated from r.stream.extract. I also have a polygon map generated from r.stream.basins, using the raster stream layer generated from r.stream.extract. I want to update the ...
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0answers
253 views

QGIS 3.18 and 3.16 LTR install. GRASS and SAGA not working. MacOS OSX

I have tried to update QGIS on Mac to either version 3.18 or 3.16 using the installers on the QGIS page (https://qgis.org/en/site/). I have been having issues getting the GRASS and SAGA providers ...
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0answers
15 views

QGIS r.regression line F significance

I performed with grass QGIS processing tool "r.regression line" a linear regression between two rasters. The result I got is shown in the picture Can someone explain to me what is the ...
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1answer
56 views

v.clean cleaning topology

I'm doing some tests with the v.clean but getting some results that I don't really know if I am the one doing something wrong or what. As you can see in the image bellow I created 3 features, one with ...
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1answer
22 views

r.thin (GRASS) not giving correct result

I have raster image of road feature. I want to extract line feature from it. So I run r.thin tool on it of parameter - { 'GRASS_RASTER_FORMAT_META' : '', 'GRASS_RASTER_FORMAT_OPT' : '', '...
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1answer
25 views

GRASS GIS v.surf.idw not working correctly

I have recently been struggling with an issue in GRASS. I am a new GRASS user and recently downloaded version 7.8.5 for my MacBook (macOS Catalina). I converted this sample dataset to a shapefile. I ...
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0answers
24 views

GRASS - Create 3d Raster map with time as vertical unit

I'm working with 2d climatic (annual max temperature) raster maps. I have 1961-1990 time period and I want to calculate 90th percentile of the climatic value within that period (so 30 maps) and inside ...
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0answers
26 views

QGIS - Network join issue with cost allocation using OSM dataset

I've been trying to create a cost allocation map, using the v.net.alloc tool on QGIS with Grass. Some of the results don't connect to the network fully, even though they should in real life. This has ...
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0answers
14 views

r.watershed: How does the convergence parameter and “AT”- lcp work?

I generated streams with GRASS GIS r.watershed, executed in RStudio. Now, I want to explain the functionality behind that function. The GRASS- manual explains a lot here: https://grass.osgeo.org/...
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1answer
56 views

Error while performing actions in GRASS GIS in Python

While performing actions in python console as described in the module of GRASS GIS,am getting following error: import grass.script as gs r.in.gdal -e input="D:...\ASTGTMV003_N19E073_dem" ...
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1answer
218 views

Does GRASS GIS work on latest Macs with M1 chip?

Does GRASS GIS work on Macs with M1 chip?
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1answer
28 views

r.slope.aspect grass gis datum format on dx and dy analysis

I'm performing terrain analysis due to photovoltaic installation on QGIS with r.slope.aspect plugin. I'm interested in evaluate differently N-S slope and E-W slope based on the PV system I would ...
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3answers
72 views

Rescale Sentinel2 data to 8 bit

I need to rescale Sentinel2 data (both lvl 1C and 2A) to 8 bit, because of the requirements of a GRASS GIS module (i.histo.match) that only works with values from 0:255. All the documentation of ...
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2answers
23 views

GRASS - r.mask analogous for vectos

I am working with r.stats. My analysis is about overlap Extreme Climatic Events (ECE) raster map with mammals range maps. I used to do my analysis first creating r.mask on ECE map and then applying r....
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1answer
81 views

Error launching GRASS GUI : error message related to gcmd.py or gi_set.py

I am trying to run GRASS GIS for the first time. However, when I try to run GRASS (by clicking on the icon in the start-up menu), I get the following error message: > Starting GRASS GIS... ...
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0answers
45 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 ...
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1answer
41 views

Installing GRASS >7.0 and its addons to use in R session

I am hoping to use the openSTARS package that relies on GRASS 7.0 within R. However, I do not understand how to proceed with the initial steps. From: https://github.com/MiKatt/openSTARS A functional ...
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1answer
54 views

Warning: skipping unsupported geometry type 'Compound Curve' when using v.transform

I am trying to transform data in QGIS from a DXF file. I keep getting the error: Warning: skipping unsupported geometry type. Compound Curve when I do a v.transform. Eventually, I want to store the ...
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0answers
24 views

Creating a GRASS addon that returns something when using read_command()

I am using grass 7.8.4. I'm calling commands externally using the Grass Python Scripting Library in Python. I wanted to know when you create an addon in Python how to end the addon script so that when ...
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2answers
63 views

Can't use simple GRASS modules in python (python script not found)

I am using grass 7.8.4. I'm trying to run some simple commands using the Grass Python Scripting Library in Python. For modules for which the source code is written in C++ or any other language than ...
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1answer
63 views

GRASS plugins not loading on Qgis 3.10.13 Coruña LTR

I have QGIS 3.10.13 LTR installed with the stand alone installer on a Windows 10 machine. In this machine I have also a QGIS 3.16.2 OSGeo installation. I can work perfectly with GRASS in my OSGeo4W ...
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1answer
66 views

r.watershed error in QGIS (3.16.2) for MAC

I'm trying to use the r.watershed tool, here is the error that is arising. I've tried changing the GRASS path to custom /Applications/QGIS.app/Contents/Resources/grass78 and it doesn't seem to work ...
2
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1answer
138 views

Generating Hough transform (Hough line transformation) of binary image using QGIS

How do I generate a Hough transform (Hough line transformation) of a binary image in QGIS? I tried in GRASS and I got Error: unable to fetch interface description for command I found from the link: ...
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0answers
29 views

Creating new mapset with Python and EPSG 4326 (Invalid north field 1N)

I am using grass 7.8. I have been trying to create a new location and then a new mapset in python. It works fine for any EPSG code except 4326. With EPSG 4326, when I try simple commands (like ...
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0answers
20 views

Deducing start and end of season information using r.seasons in GRASS GIS at 'Field' level

I would like to ask one question on using r.seasons in GRASS GIS. The information page on this function is available at https://grass.osgeo.org/grass78/manuals/addons/r.seasons.html The problem that I ...
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0answers
39 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\...
3
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1answer
31 views

Printing a multiline d.text in GRASS-GIS when using Python grass-session

Here is what I'm trying to do, but the text remain printed in one line. What is wrong? from grass_session import Session from grass.script import run_command with Session(gisdb="path to mygisdb&...

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