GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) capable of handling raster, topological vector, image processing, and graphic data.

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8 views

Python error when using r.reclass on raster with no CRS

I have a set of GRID data (directory of .adf files) that I'm trying to reclassify in QGIS. I'm using the GRASS r.reclass function to try to reclassify the layers, but GRASS keeps failing and ...
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1answer
21 views

installing grass71 on centos6

Any help please, i am installing grass71 on centos6 , i have the following message after running grass71 sincere regards [bachir@nexus ~]$ grass71 Starting GRASS GIS... g.gisenv: /lib64/libc.so.6: ...
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0answers
8 views

Can grass 7.0.3 pansharpen Landsat 8 spectral bands [duplicate]

Can grass 7.0.3 now pansharpen Landsat 8 rgb spectral bands. The last post in 2013 said that a programmer was working on it.
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0answers
20 views

QGIS and GRASS 7 integration [duplicate]

I want to integrate QGIS 2.12.3 or 2.13 with GRASS 7, but I still haven't been able to do so. Can someone please tell me how can I do this with a stable QGIS version.
3
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2answers
39 views

Keep “no data” tiles with r.reclass rules

Working in QGIS 2.8.1-Wien. I want to reclassify a raster with the r.reclass GRASS 7 tool, but want to keep the "no data" tiles as "no data". I understand that I need to create a text "rules" file ...
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0answers
20 views

My OSM country roads network is not routable [duplicate]

I need a routable shapefile in order to execute pgrouting algorithms. I download a national zip from http://download.geofabrik.de/europe/greece-latest.shp.zip and import the roads shapefile in my ...
4
votes
1answer
83 views

basin creation GRASS vs. flow direction

I have a strange behaviour in QGIS with GRASS tools. I am trying to create basins in the alp region and use he SRTM3 data. As I can see on the flow direction raster the SRTM3 data seems to act nice: ...
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0answers
20 views

GRASS unable to download any extension from GRASS Addons

I'm trying to install some add-ons to GRASS, but each time I try to download an addon, I'm getting the same error: g.extension.py extension=v.autokrige ...
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1answer
19 views

GRASS parser() error

I'm trying to use GRASS on python 2.7, but I'm having some problems at setting my script on IDLE, then I'm getting an error at parser() function: Here is my script: import os import sys gisbase = ...
0
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0answers
22 views

Cannot open r.viewshed on Grass 7

I cannot open the r.viewshed tool in Grass 7.0.3. I am using the 64-bit version on Windows 7. The error message is given below: Traceback (most recent call last): File ...
2
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0answers
15 views

GRASS GIS 7.0.3 r.in.lidar problem on Windows 10

I'm having problems to load .las files into Grass GIS 7.0.3 for Windows 10. I use the module r.in.lidar but I get this message: What can I do? How can I solve the problem? Cheers! Vincent.
2
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1answer
26 views

Using wild cards in GRASS to remove files

I have a bunch of files on a GRASS location, all named temp_something, that I want to delete. I tried to use the g.remove tool using the multiple option and typing temp* in, but it doesn't work out, ...
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2answers
18 views

Grass 6.4.3 v.rast.stats: Calculate only one value

I am using the grass (6.4.3!) function v.rast.stats to calculate the mean value of rast values over polygons. The tool is somewhat slow and I actually only need the mean value. Is there any ...
1
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1answer
55 views

How to calculate the percentage of cells which are lower than a site in Grass GIS

In GRASS GIS: I have a shapefile with 300 hundred of sites (with height values for each point), and want to calculate the percentage or number of cells (of a given DEM) which are lower than the ...
4
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3answers
51 views

How to list the available GRASS modules in command line

Using GRASS shell, I know that I can use the -help suffix to get information about a particular module. E.g. r.relief -help will return this: Description: Creates shaded relief map from an ...
1
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0answers
39 views

How to calculate the percentage of cells under a given site? [duplicate]

I am asking for ArcGIS 10.3. The case is: I have a file with three hundred of points (shapefile), corresponding with archaeological sites. For each site (point) I have the height, and want to ...
3
votes
1answer
42 views

Looking for spatial analyst tool between raster and vector layers in QGIS

I'm aiming to do a similarity analysis between a raster layer and a vector layer. The raster layer is a 5-class ice map and the vector layer (points) contains ice jam events data. The goal here is to ...
3
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0answers
24 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 ...
2
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0answers
23 views

Attribute table update after v.split on GRASS GIS

So I just used v.split to create shorter segments (with just 2 vertices) of my contour lines. I was left with about 22000 lines but, when I open the attributes table, I find no more than 45 entry ...
4
votes
1answer
64 views

How to get r.drain to run in QGIS/GRASS?

I use the GRASS GIS extensions for QGIS (QGIS version 2.12.3 with GRASS 6.4) and I have a problem with the r.drain algorithm: I simply cannot make it work with a given starting point as a vector ...
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0answers
25 views

Grass i.landsat.acca says image is cloud free but it is not

I'm working on an area in Amazonia with high cloud persistance which makes global data on land cover quite useless at small scales, so I wanted to learn to process my own Landsat images, with GRASS ...
4
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1answer
60 views

GRASS GIS temporal raster individual layer statistical summary

I have created a temporal raster in GRASS GIS which has 90 layers. I would like to extract the mean of each raster layer and export it as text file. Right now I have to export the rasters as GeoTiffs ...
1
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1answer
41 views

Solar radiation flux at 5 minute interval using GRASS GIS r.sun

I have been trying to estimate instantaneous total solar irradiance(w/m2) at five minute interval for a day (eg. 21 sept). I can do this in SAGA GIS by using "moment, mode 1" and running the solar ...
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0answers
19 views

How to define proj4 string for grass

I'm asking here because the grass mailing list suggested the proj mailing list, but with a bit more progress it seems to be a grass question. I'm not sure and I thought both communities might see it ...
2
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1answer
77 views

Capturing Output Messages from GRASS when Running Python Scripts

Thanks to the excellent documentation here: https://grasswiki.osgeo.org/wiki/Working_with_GRASS_without_starting_it_explicitly#Python:_GRASS_GIS_7 I've figured out how to access GRASS modules in ...
3
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0answers
27 views

Calculating a specific distance from points along a network - GRASS

I'm currently using the v.net.iso function in GRASS (no access to network analyst in ArcMap). Does anybody know of a way to export the result to shapefile so that you have an individual line ...
2
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2answers
32 views

How can I extract flat surfaces from a DEM with GRASS GIS?

How can I use GRASS GIS to get the flat surfaces in this DEM into polygons? The picture is used to show the clearly defined flat surfaces.
1
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1answer
24 views

How can I add r.local.relief to the QGIS Processing Toolbox?

I'm working with QGIS 2.12 and GRASS 7.0.3RC1. I'm making a model using the model builder and trying to add the GRASS addon "r.local.relief" in my QGIS model, but the addon does not show up in the ...
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0answers
28 views

Create GRASS Mapset in QGIS 2.12

How do you create a new GRASS mapset in QGIS 2.12? The GRASS panel has only the Open GRASS Tools button.I don't see any way to actually create a GRASS mapset in QGIS.
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0answers
48 views

Converting LandsatMSS DN value to reflectance using GRASS71 [duplicate]

I'm working with a Landsat image MSS by using Grass 7.1,the image's name is LM40080531988146AAA03 with format .tif, the problem is that I want to convert DN value to radiance/reflectance. I'm using ...
2
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0answers
47 views

Avoiding edges using GRASS generalization?

I'm trying to process the national wide land cover data into vector polygons. In order to be quick I separate the data into several tiles and process them in parallel. process flow is : 1. v.in.ogr ...
3
votes
1answer
67 views

Get results from using GRASS algorithms with the QGIS processing tool

I am trying to write a plugin in QGIS that uses at some point a GRASS algorithm : "v.split.length", accessible by using the processing class, and here is how I am using it : ...
3
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0answers
44 views

Wrong area using Albers Equal Area Projection in GRASS for Java, Indonesia

I am just getting to know GRASS 7.0 and I am struggling finding a good projection to work on a spatial analysis of Java, Indonesia. I am new to the forum, so if information's are missing for a better ...
1
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2answers
71 views

Vector to raster conversion [solved]

I'm using GRASS but, in case, I'm also familiar with R and QGIS. I'm trying to convert a vector area map into a raster one. My problem is that the resolution of the raster is too low (and I can't ...
0
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0answers
24 views

A vector object not being replaced in temp folder when using 'for' loop in R

I am currently running GRASS GIS through R interface and got stuck at this point; where I am using a 'for' loop in R, and the code is as follows: for(i in 1:nrow(Snapped_SSP_DSN)) { ...
4
votes
2answers
66 views

How can I calculate flow length in QGiS/GRASS?

I have these rasters: DEM Flow Direction Flow Accumulation I would like to calculate the flow distance of every pixel to the outlet of a basin. In Arc-GIS, I can use the flow length. But I don't ...
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0answers
19 views

GRASS: strange classification output and reject map from “i.maxlik”

I am trying to perform a supervised classification with "i.maxlik". I have three bands: 1) elevation (a dem); 2) reflectance (derived from Landsat ETM+ band4); 3) cumulative solar radiation (derived ...
2
votes
1answer
34 views

Error while executing v.rast.stats command in grass plugin in qgis

I have a vector polygon which I imported in grass. I also have a raster from which I have to extract the value. I ran v.rast.stats command in QGIS 2.12. The command was executed with error. The error ...
1
vote
1answer
29 views

Unable to open shapefile with GRASS GIS? [closed]

Is GRASS GIS able to work with a shapefile (*.shp)? I can´t open my shapefile (328000Kb) in that program. I want to dissolve a shapefile in GRASS because on QGIS the process is very slow.
4
votes
1answer
80 views

What happened to the GRASS Browser in QGIS?

In the past I could display the imported layers in the GRASS toolbox within QGIS. This was possible under the tab "Browser" as you see in the image. Lately I'm missing this tab. The QGIS version is ...
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0answers
53 views

Making GRASS GIS 7 Ubuntu bash file work on Windows 7

I have created this bash file (.sh) while working on watershed analysis stochastic simulation in GRASS GIS 7.0.2RC1, which is running on Ubuntu. It worked perfectly and I received the correct results. ...
1
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0answers
16 views

i.spectral tool error

system description: Windows7 32 bıt OS, Grass GIS 7.0.0 Gnuplot 5.0 Solution attempt 01: On the basis of following thread, commented out said path check lines from i.spectral.py script: ...
1
vote
1answer
28 views

how to calculate the mean value of pixels of a raster in Grass plugin in qgis?

I am using grass plugin in qgis 2.12. I have to estimate the average value of all the pixels but don't know how to do it.
1
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1answer
25 views

Calculating Categorical Raster Areas per Polygon

I've got forest fragmentation data from which I've extracted pixels that correspond to forest edges and patches. I've also got a shapefile of counties in a US state. I'm trying to get the area of ...
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0answers
32 views

QGIS opened as Grass - with no QGIS GUI [closed]

I downloaded QGIS 2.12.1-1 x86 64; but when I opened the installed software under the title QGIS, a Grass interface came up. There is no QGIS GUI with a GIS format (Pan, enlarge, ect)
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0answers
20 views

grass r.watershed to larger rivers parallel lines to same stretch

I'm trying create stream channels with r.watershed grass64. However, it shows two or three parallel lines for the same stretch of river. The river is large in some parts, but is just one river. Does ...
4
votes
1answer
41 views

GRASS 6.4 Reinstallation for Ubuntu

I need to reinstall GRASS 6.4 on this Ubuntu computer due to compatibility issues. I had installed GRASS 6.4 a few weeks ago to work with a simulation program. I used the command apt-get install ...
2
votes
0answers
33 views

C/C++ function to return minimum set of points required to represent a geometric shape

I am looking for a method from Grass, GEOS, or similar that will delete those points in a geometry which do not affect its shape. Example 1 +----+----+ p0 p1 p2 p1 can be deleted without ...
4
votes
1answer
44 views

Why can't I see v.net in QGIS GRASS tools

I have noticed answers such as Is there an open source tool to planarize graphs? stating you can use GRASS v.net from within QGIS. However I can't see it - my QGIS processing GRASS toolbox contains ...
30
votes
4answers
552 views

Generating equal sized polygons along line with PyQGIS?

I would like to create polygons along a line to use them for AtlasCreator in a next step. ArcMap has a tool called Strip Map Index Features. With this tool I can choose the height and width of my ...