Questions tagged [qgis-grass-plugin]

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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 ...
4
votes
0answers
138 views

Layers from GRASS db won't load in QGIS 2.18.4 desktop

I have been learning QGIS online but now I am stuck at a module. I am supposed to launch a project that includes GRASS vector and point layers. However, when I do so I always receive the 'Handle bad ...
3
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0answers
71 views

How to determine Kc value and apply it to r.sun?

As outlined in this link ( r.sun delievering unrealistic Values ) to get realistic values of kilowatt / meter-2, you must multiply the results by a "clear sky factor (Kc)". The link comments recommend ...
3
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0answers
726 views

Travelling Salesman in QGIS using GRASS

I would like to use the travelling salesman algorithm in the GRASS plugin in QGIS. I have a points layer (3 points) and a road layer. I have connected the 2 together using v.net and I am given this: ...
3
votes
0answers
203 views

Using GRASS v.rast.stats: Rast stats layer not correctly generated

I want to use the GRASS tool v.rast.stats for extracting information from raster data. I need average, mean, number etc. for each of the 15 polygons. When I run the tool, following message appears at ...
2
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0answers
18 views

QGIS Grass-plugin output does not match the CRS of input files nor project CRS

My project CRS and raster layer are EPSG:31467. However, when I use for example r.to.vect to create a polygon from the raster, the created vector layer has an unknown CRS and is a little bit off (does ...
2
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0answers
70 views

Using GRASS and v.split with QGIS

I have been working with QGIS for a few years now and am just now having issues with the GRASS module. Ultimately, I am just trying to split a line (river) into 100m segments, and have found the ...
2
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0answers
160 views

r.series GRASS algorithm in QGIS 3.2 output no-data image

I'm trying without success to calculate a standard deviation image from 4 input images. I already used the r.serie algorithm in 2.18 to calculate an averaged image. Know after upgrading to 3.2.2 on ...
2
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0answers
84 views

No attribute table or values in QGIS 3.2 Grass toolbox plugin output files

Using the Grass toolbox within QGIS 3.2 (and previously 3.0) when I import any files and overlay them, then use the "View Output" option (button), the resulting file has the correct polygon areas ...
2
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0answers
71 views

Generating ground control points with GRASS?

I want to find out matching ground control points in two images for auto georeferencing and grass manual says that i.points.auto will do the job. I am using Grass 7.2 but couldn't find this plugin.
2
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0answers
203 views

QGis 2.18 (and other tests on QGis 2.14) hangs with GRASS 7 editing session (OS Windows 8and 10)

I installed QGis 2.18 (64bit and 32bit versions) and i started a session with GRASS 7 in Windows 8 environment (the same thing I did on another workstation with Windows 10). I loaded a test layer with ...
1
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0answers
43 views

How do I split polygon into line segments?

My question exactly matches with this one : How do I split polygons into line segments? but the solution is outdated, I am not able to find v.type.bl option under the grass dropdown in QGIS 3.8. ...
1
vote
1answer
134 views

QGIS GRASS using v.drape FileNotFoundError: No such file or directory: '/usr/local/Cellar/osgeo-grass/7.6.1_5/grass76/etc/lock':

I'm running QGIS 3.8.3 and am trying to use v.drape. When I run it from the processing toolbox, I get a FileNotFoundError that's pointing to a strange /usr/local/Cellar/osgeo-grass.... folder. I'm ...
1
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0answers
90 views

GRASS r.sun returns “ERROR: insol_time and incidout are incompatible options”

I'm trying to measure irradiance on a DEM using the r.sun tool in QGIS 3.6. I have grids for the elevation (EPSG:32735 - WGS 84 / UTM zone 35S), the slope and aspect (EPSG:4326 - WGS 84). I've tried ...
1
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0answers
12 views

Inner workings of GRASS reclassification on QGIS. How does it work with multiband rasters?

I have a 33 band raster layer I need to reclassify. I tried using GRASS module inside QGIS and it worked out fine, except that it outputs a raster with a single band. Which band of the 33 did it ...
1
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0answers
25 views

Building graphs between two point layers

I am trying to run a script to find the shortest routes between two sets of point layers (Blue star and Green dots) in QGIS using road network. I am able to use GRASS gis "v.net.distance" ...
1
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0answers
57 views

Working with GRASS gis in pyQGIS

I am looking for a way to loop through GRASS gis v.net.distance in QGIS. I want to iterate over all the 3 layers which has multiple features at the same time, and print the shortest distance for each ...
1
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0answers
74 views

Can't get GRASS 7 V.kernel.vector to work on QGIS 2.18.14

I have reinstalled GRASS multiple times, with all of the necessary listed programmes to install beforehand (e.g. GDAL), and it won't work. The error comes up - GRASS was not found in '/Users/Shared/...
1
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0answers
115 views

solve Topology error in Grass using QGIS?

I want to build a raster from a vector layer by using "v.to.raster.attributes" in QGIS but its not working and give me an error to build a topology using v.build. I build it but after that i have no ...
1
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0answers
61 views

Error “std::exception” in GRASS GIS via QGIS

Does anyone know what this error means? I am using the GRASS GIS plugin in QGIS and I have imported a road layer (vector) using v.in.ogr.
1
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0answers
100 views

GRASS within QGIS - can I access grass modules through shell?

I have QGIS/GRASS installation and I would like to do my process workflow through shell in Ubuntu. It is raster vectorisation -> selection by value -> saving as shp. I have done first step by gdal ...
1
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0answers
289 views

Linux QGIS 2.18.4 GRASS7 tools not working

GRASS tools are showing & GRASS 7 shows as activated in the Providers menu, but I get the "Missing dependency, GRASS isn't configured properly" message. How do I configure it properly? GRASS 7.2 ...
0
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0answers
15 views

GRASS Tool r.stats.zonal for QGIS 3.14 Pi is not working in batch mode

I am trying to calculate the averages and standard deviations of the pixels of a group of 31 vegetation index rasters calculated from Landsat images, but only where these rasters intersect the ...
0
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0answers
65 views

QGIS 3.10 LTR GRASS tools not working

Having difficulty with the new LTR GRASS functions. Typical workflows that worked in 3.4 LTR but not 3.10 LTR: -Open RGB mosaic -Use the raster calculator to extract the red channel -Use r.texture ...
0
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0answers
32 views

QGIS GRASS tools output has only “cat” column in attribute table - missing full attribute table

Using the GRASS Tools plugin in QGIS 3.10.2 with GRASS 7.8.2 I have imported a series of layers and used the "v.overlay.or" algorithm to "union" them. This has worked successfully many times and once ...
0
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0answers
444 views

QGIS GRASS plugin not found?

I have seen this question come up before and have tried the related fixes as best as I could but nothing seems to work. I am running the most recent LTR of QGIS, 3.4.8 but my GRASS plugin cannot be ...
0
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0answers
103 views

GRASS function “V.net.centrality” Error env: python3: No such file or directory

I am using QGIS 3.4 (just updated) on a Mac OSX Mojave 10.14. I am trying to use the grass function "v.net.centrality" but I keep getting an error. The error is ... env: python3: No such file or ...
0
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0answers
63 views

Slope rasters - different results from different tools

I'm calculating Least Cost Path (LCP) within QGIS 2.18. The first step is to produce the slope raster from the DEM. Using r.slope in GRASS produces excellent results where I can go on and finally ...
0
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0answers
296 views

Distance calculation with v.net.path in QGIS 3.2

I have 3 layers: origin and destination point shapefiles and network line shapefiles. I want to calculate the shortest path on the network between the origin (250 features) and destinations (20 ...
0
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0answers
152 views

Missing v.stream.order of GRASS in QGIS processing tool

I want to use v.stream.order of GRASS in QGIS for stream but it is not available in QGIS processing tool. How to add that in processing tool QGIS version 2.14.17-Essen