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.

Filter by
Sorted by
Tagged with
0
votes
1answer
24 views

Opening .Jp2 image in QGIS on Mac?

I am trying to open a Jp2 file in QGIS 3.4.5 on a macOS 10.14.5 Mojave. I am new to QGIS and have been looking through forums that discuss GRASS and GDAL but I don't understand the connection to QGIS....
1
vote
0answers
33 views

Using Spyder (Anaconda) environment to execute GRASS Python script in Windows 10 [on hold]

How can I set my spyder environment in order to use GRASS Python script in Spyder for Windows 10? I need to use some Python script from GRASS GIS. I am really new in Python and manipulate with scripts....
0
votes
0answers
6 views

GRASS GIS - r.in.usgs plugin TNM API Error

I'm having a problem with my GRASS GIS r.in.usgs plugin. I've never had this happen before. I'm trying to download any product (NED, NAIP, NLCD), but none of these work. ERROR: TNM API Error - [u'org....
1
vote
0answers
33 views

How to install GRASS Add-On after migration from SVN to Github?

I'm new to GRASS and in the past I have had no issue installing add-ons. Recently I tried to install "r.stream.order" and got the following error: g.extension extension="r.stream.order" Extension ...
2
votes
2answers
35 views

Creating new GRASS locations while looping in Python script

I am making a Python script for processing my data. import grass.script as grass import numpy as np def main(): f = open("D:\\Glaciers_selected.csv", 'r') fl = f.readlines() for x in ...
0
votes
0answers
30 views

Grass GIS: g.extension – Not found

I'm having problems trying to compile (r.landscape.evol and another) on the 7.6.1 version of GRASS from the g.extension command. It does not found the file in the default repository. I am running ...
0
votes
1answer
16 views

Error when trying to access variables in the GRASS startup program

I am able to create a new location using the Location Wizard, however I would like to create a GRASS location in a Python script, so I was figuring out this can be done from the console. In the ...
1
vote
1answer
38 views

GRASS GIS changes shape of tiff file when imported

I do have a raster which shows 13 rows and 16 columns when viewing it with Windows Viewer and also when using imread for loading it into python. I want to work with my dataset in GRASS. My steps: ...
2
votes
0answers
20 views

Using V.clean.snap?

I'm working on creating a road network of pedestrian walkways. Since all data were manually drawn, I'll need to snap the vertices together to form a consistent road network on which I can run routing. ...
1
vote
2answers
41 views

How to display a map from a script in Grass Gis 7.6.1

I am working with Grass Gis and spyder (IDE) and I am trying to display a map on "Spyder console" from the command line of spyder. I have a raster map call "elevation" and i tried this script: import ...
3
votes
1answer
60 views

3D population density map

I'd like to make a 3D population density map about a country. I've got all of the population data of the towns and villages etc. and I've got shp about these areas. I'd like to make a map like this:...
1
vote
1answer
30 views

v.voronoi.skeleton error

Recently, I was looking for way to skeletonize buffer and besides solution with PostGIS and Postegre solutions there is algortihm v.voronoi.skeleton. I have tried to use it with different road/rail ...
2
votes
1answer
28 views

QGIS i.landsat.toar not reading .txt file

I am having an issue with GRASS i.landsat.toar tool. It will not let me choose my metadata .txt file. I click on the three dots to the right of "Name of Landsat metadata file (.met or MTL.txt) [...
2
votes
0answers
36 views

Getting results from processing.run GRASS r.resample in PyQGIS

I am trying to get output from r.resample in a stand-alone PYQGIS application. The code runs and does not show any errors, but it does not save an output file (i.e. 'c:/path/to/output.tif'). As far as ...
3
votes
1answer
47 views

GRASS not working with QGIS 3.7

Like the author of GRASS not working with QGIS 3.6, I am unable to use Grass plugins, with the error: This algorithm cannot be run :-( The specified GRASS 7 folder "C:\OSGEO4~1\bin\bin" does not ...
2
votes
0answers
52 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 : ...
2
votes
1answer
31 views

GRASS 7.6 v.net.iso not providing output in QGIS 2.18

There are simply two layers in EPSG:31469 both are located on the Server side, see image below: points 'HST_Bestand_GK5' polylines 'vwESKN_1_25000_Teil' On my Windows 10 with QGIS 2.18 and GRASS 7.6,...
1
vote
1answer
22 views

start GRASS 7.6.1 with OpenCl from windows prompt

I desperately tried this code and variations: grass76 LOCATION_NAME=32632 GISDBASE=C:\Users\706774\Desktop\xxx\grass_database MAPSET=PERMANENT --with-opencl --gu but I get this error: ERROR:...
0
votes
0answers
67 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 ...
1
vote
1answer
19 views

How to mask raster image (DEM) on QGIS Grass

I am doing research at graduate school. Using QGIS GRASS, I made a raster image (DEM) by spline interpolation from point data. Next, I decided to limit the range to within the vector (within the point ...
0
votes
1answer
32 views

R.Viewshed Not Working

Getting the following error message when running r.viewshed Processing algorithm… Algorithm 'r.viewshed' starting… Input parameters: { '-b' : True, '-c' : True, '-e' : False, '-r' : False, '...
0
votes
1answer
20 views

Extruding vector using one of its attributes in GRASS?

I'm following this tutorial: https://grasswiki.osgeo.org/wiki/Extrude_2D_polygons_to_3D. This is what I've done so far (inside GRASS): - Import a DEM HGT file: > r.in.srtm input=S23W043.hgt --...
2
votes
1answer
86 views

Retrieving lines radiating from point with v.select in GRASS GIS 7.6

I am attempting to select lines that radiate from a point using v.select in GRASS GIS 7.6 (also tested with 7.4.4) in Windows 10. I start out with 48 lines radiating from a point every 7.5 degrees. ...
1
vote
0answers
21 views

GRASS GIS: Time series of overland flow from r.swim.water

I am trying to perform an overland flow routing on a large area using r.sim.water in GRASS GIS. I've looked at other answers and made sure to set my computational region to the elevation raster I'm ...
3
votes
1answer
52 views

Generate a viewshed and merge it with another image using GRASS/GDAL command line? [closed]

I've found a tutorial showing exactly what I want to do (merge viewshed and hill shade or map) but unfortunately it is for QGIS users and I need it in pure command line instructions because I'm in a ...
3
votes
1answer
64 views

r.surf.contour for large area

I have a vector file containing contour with 2m accuracy, covering a large area (All Hong Kong). I tried to generate an elevation raster map with the file, by first rasterized the vector, using v.to....
1
vote
1answer
45 views

Install QGIS 3.4 with GRASS support in Ubuntu 18.04

I can install QGIS3.X but cannot run a GRASS process. I get the popup: This algorithm cannot be run :-( GRASS 7 can't be found on this system from a shell. Please install it or configure your ...
0
votes
0answers
20 views

Error installing r.stream extension, GRASS GIS on MacOS

When I attempt to run: g.extension r.stream.order I get the following error: Fetching <r.stream.order> from GRASS GIS Addons repository (be patient)... Compiling... clang: warning: no such ...
1
vote
1answer
38 views

How to use GRASS v.buffer function in QGIS?

Trying to use the v.buffer function to create a 500-foot buffer (map units are in metres, which is why I put 152.4 meters as the buffer distance) around the boundary of a property parcel (not the ...
0
votes
0answers
27 views

GRASS GIS: From multiple lines to single line

This seems like a simple process but somehow I am not able to solve this. The situation is as follows: I have three separate lines which form visually 1 line. As I want to further process these lines ...
2
votes
3answers
100 views

Creating square buffers with v.buffer in GRASS GIS

I do not seem able to create a square buffer around a point feature with v.buffer in GRASS GIS v.7.4.4. The documentation states that "Using -s with a point vector map as input data, square buffers ...
3
votes
1answer
141 views

GRASS GIS producing different slope than GDAL?

When producing a slope in GRASS GIS 7.4 the results are different than with QGIS (GDAL) and ArcMap for the same input data and same parameter (Z ratio is 1.0 and degrees). QGIS and ArcMap generate ...
2
votes
0answers
18 views

How to work with a freshly imported vector?

I have a text file with points coordinates: $ cat ControlPoints.txt -10153967|8326376 -10621243|8176811 -11122894|8184333 -9657869|8379692 -10014696|8056719 -10014696|8056719 I import them with v....
0
votes
0answers
27 views

PyGRASS: storing attribute table values to variables

Goal: to store the sum of all values (lengths) of a vector map in a variable inside a Python script. This variable will later be shown to the user in a GUI. The computation time has to be as low as ...
0
votes
1answer
31 views

Computing x and y distances between two raster maps using GRASS GIS?

I am working with a maximum water elevation raster in which, similarly to using r.grow.distance, I am trying to extract the distance from the each null cell to the nearest water elevation cell. ...
2
votes
2answers
55 views

GRASS GIS: Computing center line of raster feature representing a river

My goal: Convert a raster layer representing a river feature (see picture) to the center line of the river stored as a polyline feature. Limitation: The whole process has to be automated. I can ...
0
votes
0answers
53 views

GRASS GIS: connecting vertices with lines along following Node Number

My goal: Convert vertices to a poly line describing the general route to have 1 line describing the center line of a river. Limitation: The whole process has to be automated. The raster can ...
0
votes
0answers
17 views

r.surf.area is underestimating area and giving negligible area

I am using r.surf.area in GRASS GIS to estimate surface area of a DEM. DEM is in EPSG4326 WGS84. It is giving a negligible area. Please give solution to this. Following is the output of r.surf.area.
0
votes
1answer
42 views

Creating Vector Attribute Field with Raster Value in QGIS

I want to create a new attribute field contains data coming from a raster in a vector file. I tried the GRASS v.drape tool but the analysis did not create any new field in shapefile. Also, I tried the ...
1
vote
0answers
23 views

Importing GRASS [closed]

I tried to run i.atcorr in a system in which GRASS GUI was not installed. I copied all the required libraries to one folder and set environment variable to that location. But while importing raster ...
1
vote
0answers
30 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
vote
1answer
70 views

r.surf.area command of GRASS GIS is giving a very small area

I am a beginner to GIS systems and am trying to calculate the surface area of a dem using r.surf.area command of GRASS GIS. The surface area it is giving me is unacceptable as it is very small. It is ...
2
votes
0answers
19 views

How to use the GRASS GIS v.net.timetable tool in QGIS?

The GRASS GIS v.net.timetable tool needs the following input information: (a) a vector layer with the network (b) a vector layer of points (from - to) (c) and the timetable. The GRASS manual on the ...
-1
votes
1answer
39 views

GRASS: what to do when the SQLite database becomes busy?

Every now then the SQLite database used internally by GRASS becomes unavailable or locked and the modules do not finish (see example below). This happens with different modules, primarily when ...
1
vote
0answers
22 views

Converting vector to raster on-the-fly using GRASS?

EDIT: I later realized that, instead of creating multiple 256 x 256 tiles, I could just create a single image to overlay on the entire map. However, I'd still like to know if there are better ways to ...
1
vote
1answer
21 views

Regrouping raster values from range to one value using GRASS GIS?

Using GRASS GIS is there a way to give a certain value for 3D raster cells that fall within a certain range, whether it's by using module (reclass, recode, r3.mapcalc)? Another alternative would be ...
0
votes
0answers
48 views

Getting error running GRASS GIS 7.6.1

Here is the error notice I receive after starting GRASS GIS 7.6. I am not sure what is the source of these errors. I had reinstalled the application but it didn't fixed these errors. What are ...
1
vote
1answer
28 views

v.generalize in QGIS throwing “Unable to create table” error

I am trying to smoothen few polyline shapefiles using v.generalize in QGIS 3.4. But it's not working. Even i tried the same in QGIS 2.18. Getting the same error. Tried the same process in GRASS 7.4.2....
3
votes
1answer
64 views

Find radius of curve?

Using QGIS with GRASS I have found a route through r.drain but it has many sharp curve. the maximum radius of curve allowed to me is 176m. Is there any to reduce the curve sharpness to 176m or at ...
0
votes
0answers
14 views

Meaning of required parameters for Morans I of raster in GRASS

I have used the Polygon to Raster tool in ArcGis a convert a vector inside shape file to a raster in TIFF format using one of the vector attributes Using https://grass.osgeo.org/grass76/manuals/...