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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4
votes
1answer
669 views

Pansharpening radiance/reflectance of Landsat 8 in GRASS 7?

first at all, I have to say that I'm new GRASS user. I would like to make a pansharp in GRASS 7 with reflectance Landsat 8 bands. I have revised some related posts and blogs, and I didn't find out if ...
6
votes
3answers
5k views

How to calculate LS Factor of Watershed for RUSLE Calculation?

I managed to get subbasins for my catchment (7 km^2) with their areas but I haven't figured out how to get the LS factor (see Revised Universal Soil Loss Equation) from it. I have the vector file ...
0
votes
1answer
40 views

-32768 in flow direction values of Grass GIS

I was checking the values of a flow direction tiff created with Grass GIS and the values were: -32768, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8. This answer explains clearly the meaning of the values ...
0
votes
0answers
20 views

Merging polygons, only contiguous [duplicate]

I have a lot of polygons (20,000). Some of them are contiguous. Some not. (see picture) I want to merge the contiguous polygons into one. Does anyone know a function to solve this automatically with ...
1
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0answers
33 views

Fixing Topology (Gaps and Overlaps) in QGIS

I am digitizing a new polygon shapefile of property boundaries based on orthoimagery using QGIS Zanzibar. I'm acquainted with topology editing in ArcMap using geodatabases. I did so with snapping to ...
0
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0answers
35 views

QGIS Grass 7 r.fill.dir

The following layers were not correctly generated.C:/Users/JIM/AppData/Local/Temp/processing_e2688a45d8934d16a2269a7ef6af8cbd/7eefcc8d13144f598fa7ab5bb5d657b8/output.tifYou can check the 'Log Messages ...
1
vote
1answer
33 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
vote
1answer
41 views

Georeferencing CAD drawing and setting ground control points in GRASS?

I'm fairly new to QGIS and Grass GIS, and learning the interface. I have a CAD drawing that has no coordinate system assigned and needs to be georeferenced to NAD83 HARN Northern Colorado (feet). I'...
0
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0answers
23 views

GRASS GIS - 'cat' directory showing 0 categories for reclassified DEM?

I am trying to use an online model (Titan2D) which requires a material map (a DEM that has been reclassified so that each group can be assigned a value of constant bed friction angle once it has been ...
1
vote
1answer
38 views

GRASS: db.in.ogr fails where v.in.ogr succeeds

This is a follow up on a previous question on the storage of vectors layers imported from PostGIS. To importing a spatial table from PostGIS I use, sucessfully, the following formulation with v.in....
0
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1answer
146 views

Opening Esri Geodatabase file with GDAL/QGIS/Grass?

EDIT: I have a 64-bit installation of QGIS but 32-bit Microsoft Office Access drivers. It has been suggested that this is the cause of the problem, which is also indicated in this post: https://www....
1
vote
1answer
18 views

v.out.ogr to PGDUMP using COPY

I am exporting a grass vectior dataset to a Postgis dump file using v.out.ogr (reformatted for clarity) v.out.ogr -a -n input=my_layer@mapset\ output=my_sql_file.sql format=PGDUMP It ...
1
vote
1answer
49 views

Solving QGIS inconsistency between file names

I'll describe my particular case but I'm sure it's a more general problem. I'm using the r.horizon plugin (GRASS 7.4) in QGIS 3.8.3, which should produce an output raster file for every direction I've ...
0
votes
1answer
66 views

Install GRASS GIS extension r.pi including r.pi.prox and implement the Addon in QGIS

I would like to install the GRASS GIS addon r.pi within QGIS, I only have access to basic GRASS commands I installed QGIS using the osgeo4w-setup-x86_64.exe advanced installation using the http://...
2
votes
1answer
151 views

QGIS 3.8 not running GRASS

I am having trouble initializing the GRASS plugin.I've tried un-installing and re-installing QGIS already. But the following message keeps appearing. GRASS init error : GRASS was not found in '/usr/...
1
vote
2answers
133 views

Adding time stamps to animation slides with OSS tools [closed]

I would like to create an animation from a set of PNG files and apply labels (time lapse values) on each of the PNG files. The PNG files were actually heat maps that were generated by interpolation. ...
5
votes
0answers
358 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....
0
votes
1answer
33 views

Why doesn't wx graphical modeler Grass gis 7 work properly in Spanish?

I am working with the wx graphical modeler in grass gis 7. When I try to use a variable call "archivo" in spanish, wich is "file" in english, it does not work. The variable dont let me choose a file. ...
0
votes
1answer
65 views

GRASS: Can v.buffer use geodesic distance like r.buffer does?

Question: In GRASS GIS, can v.buffer use geodesic distance like r.buffer does? If v.buffer can't use geodesic distance, is there a way to do vector geodesic buffering (ideally in GRASS, but I can ...
0
votes
0answers
20 views

Combine duplicate geometries into single records with v.clean in QGIS 3.6

I have a points file that contains multiple duplicate geometries. I am using the QGIS "Processing Modeller" to clean up data, and want to identify duplicate point geometries and combine so that I ...
0
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0answers
22 views

Running pygrass on Linux(Mint) based on GRASS 7.8

I want to try out the pygrass API and I dont want to use GRASS cli. I would like to write a python script, import the pygrass and play around with common algorithms eg distance, buffer etc. On my ...
0
votes
1answer
8 views

basin layer from r.water.outlet Tool has values but is not rendering anything

I'm trying to deliniate a watershed with QGIS and used this tutorial to do so https://geogeek.xyz/catchment-delineation-with-qgis.html 1) r.fill.dir to create depressionless DGM 2) use r.watershed ...
2
votes
1answer
187 views

How do v.distance 'upload' parameters actually work?

I'm trying to use v.distance (using QGIS 3.4) to calculate the distance in meters between a layer of water shutoff points and the boundary of the nearest building footprint polygon. Even better would ...
0
votes
0answers
15 views

Incorrect result when using v.net.distance on grass76

As shown in the image below I need to connect the points in yellow to the respective nearest point in brown via the shortest path on the road network in blue. I decided to use v.net.distance on ...
0
votes
1answer
325 views

Installation of QGIS 3.4.4 on Ubuntu 16.04 fails to install qgis-plugin-grass because of uninstallable grass760 dependency

I have used the instructions here marked Tested 29/06/2018 to install QGIS 3.4.4 on Ubuntu 16.04. While QGIS installs nicely I get an error on installing qgis-plugin-grass. Subsequently the Grass ...
2
votes
1answer
272 views

Getting GRASS 7.4.4 Working in Python 3

I'm trying to get some GRASS functionality in a Python Script, specification r.series, but I'm struggling to import GRASS. I'm trying to uses the method outline on the GRASS Wiki, Working with GRASS ...
2
votes
1answer
371 views

GRASS not working in QGIS, standalone

*Running QGIS 3.6, GRASS 7.6; have both Python 2 and 3 I'm trying to run a GRASS algorithm in QGIS, and none of the GRASS tools are working. GRASS also isn't working in the standalone version. I have ...
13
votes
1answer
791 views

GRASS Processing not working on QGIS?

I've been having several issues making GRASS algorithms work from the Processing toolbox. When you fresh install QGIS 3.4 (MacOS High Sierra), first it doesn't find python -- which I solved by ...
1
vote
0answers
38 views

GRASS GIS r.mblend: Data base element issue

I'm using r.mblend within Grass GIS v7.6.1 on Windows, attempting to merge higher resolution raster files (1 m) with lower resolution (5m). All is running until the print out step "Dropping extra ...
1
vote
2answers
627 views

Problem with Bash loop in GRASS GIS

I'm new to GRASS GIS and programming and I'm running into a lot of what I imagine are beginners problems and something similar to this has been asked before, but not In a way that I understand. I'm ...
-1
votes
1answer
109 views

r.stats output parameter error

The "r.stats" tool gives "ERROR: r.stats: Sorry, is not a valid parameter" error and it creates empty file.
3
votes
1answer
73 views

PYQGIS 3 Using the ouptut from GRASS v.distance algorithm

I have a script which is trying to run v.distance on two existing shape files, buildings.shp which containing some polygons and singleasn.shp which contains a single point. This will be run from the ...
0
votes
0answers
21 views

Combining cost analysis and voronoi-like area interpolation regarding slopes

I have DEM raster data of an island and I have 10 points (cities). My task is to map the island into areas. Inside these areas everything must be nearest to the corresponding city/point, and each ...
1
vote
0answers
27 views

Routing for Waste Collection (U-Turn problem)

A general question about routing problem: I am working on waste collection problems and I am having some trouble with some routing problems (the truck has to pass by every bin). So far I have tried a ...
1
vote
0answers
32 views

GRASS error after installation

I have installed GRASS GIS 7.6 and when launching it, the next error shows: ERROR: The APPDATA variable points to directory which does not exist, ask your operating system support Exiting... Press ...
1
vote
1answer
1k views

Cleaning shapefiles with islands in GRASS GIS?

This may be very simple, but I'm new to GRASS GIS. I have a large shapefile containing global species ranges, which needs topological cleaning. I imported this into GRASS GIS 6.4.3 using v.in.ogr (a ...
2
votes
0answers
33 views

Connecting points to lines via network layer in QGIS

So I have a set of three layers: A set of points A road network layer A line layer (e.g. which represents a cable) I need to find the shortest paths which connect the points (Layer 1) to the line ...
2
votes
0answers
48 views

Wang's Bend Simplify in QGIS

I am looking for an alternative to ESRI's Simplify Polygons - Bend Simplify method (I only have a Basic License). Is there an existing QGIS plugin which supports this specific polygon simplifying ...
1
vote
1answer
48 views

Where can I find the GRASS add-ons metadata?

I am trying to install grass7 addons locally. I have downloaded them and am using the url=path version of the g.extension command line. I get an error as follows: g.extension url=/home/user/source/...
2
votes
1answer
331 views

Watershed Delineation Loop - r.water.outlet resulting in NAN area while snapped

I am attempting to create multiple watershed delineations for stations within a CSV file. I have files for flow direction (raster with a cell size of 30m), flow accumulation(raster with a cell size of ...
1
vote
0answers
23 views

Using v.net.connect on QGIS 3?

I am trying to find out if the v.net.connect GRASS tool is on QGIS 3.4 because I'm not finding it anywhere in the toolbox. I have to be reverting to QGIS 2.18 to run this tool.
1
vote
0answers
31 views

Get error using r.reclass in QGIS 3.4

I am trying to use r.reclass function on a Land Cover raster in QGIS 3.4. The operation is quite basic stuff and the settings are attached below. However, I get an error that prevents the creation of ...
2
votes
1answer
80 views

Getting the 'memory:' layers after grass7:v.clean processing using PyQGIS?

To repair geometries errors, I'm now trying processing (grass7) using PyQGIS. For one polygon layer (QgsVectorLayer: 'hn_pg'), I wrote the below script and run the grass7:v.clean algorithm. The ...
0
votes
0answers
11 views

Error with v.net

When running v.net on CentOS 7 I ran into the following error: GRASS 7.6.0 (srilanka2):/tmp/final > v.net input=roads points=bs output=network op=connect thresh=5000 Copying features... 100% ...
0
votes
2answers
99 views

d.rast multiple times

I am using GRASS 7.2.0 on Windows 8.1 and I have 107 raster files, converted from r3.to.rast which I want to display all at once. I put in Python console (2.7.5) every name of rasters into variable d ...
3
votes
2answers
120 views

Automatically fill gaps and merge freshly generated polygons with the longest adjacent polygon

I get polylines automatically generated from AutoCAD from a colleague. Converting them into polygons with QGIS 3.6, I find out some sliver polygons and gaps in between, as shown in the picture below : ...
16
votes
4answers
5k views

Manually correcting raster DEM (OpenSource)?

Is it possible, to correct a raster DEM by changeing the raster-cell-values manually, like by "painting"? My DEM (ASTER) have one small error where the elevation is about 300m below the actual ...
3
votes
1answer
202 views

QGIS v.net.steiner 'not correctly generated' error

I'm trying to generate a Steiner tree in QGIS 2.18.2 using a simple set of points, and a simple line vector. See the screen shot below: I then open up v.net.steiner, set the points and vector ...
3
votes
2answers
3k views

Specifying GISBASE location for QGIS install?

I am just a beginner at this QGIS and GRASS and I am using this QGIS 2.0.1 Dufour which throws a error at the startup that "QGIS couldn't find your GRASS installation. Would you like to specify ...
5
votes
3answers
7k views

New QGIS install not finding GISBASE? [duplicate]

At QGIS startup I get the message: "QGIS couldn't find your GRASS installation. Would you like to specify path (GISBASE) to your GRASS installation?" (Windows 7) No amount of rooting around the ...