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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51 views

Shell/GRASS: Exit loop upon raster value

I am running a loop from a shell script in GRASS GIS 7. Basically, values are subtracted from a raster in each step. I want the script to stop/exit if any of the raster values is 0 or less. Is there a ...
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56 views

Splitting lines at a specified distance and add attribute

I have used QChainage to create points along a line every meter. What I am ultimately looking for, is to split the line layer along this point into segments with the chainage distance as an attribute. ...
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1answer
170 views

How to visualize a point cloud in 3D with GRASS?

I'm new with qgis and grass so I'm sorry if there is a straightforward answer for this question but I can't seem to get it done. I've imported a pointcloud into qgis from a datafile. Now i'd like to ...
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1answer
30 views

GRASS 7.0.0beta3 / statistics change after TIF import?

I'm new to this forum, and pretty much a beginner with GRASS (7.0.0beta3 installed atm). So my question is the following: Statistics (mean, min, max) change quite a lot after importing a .TIF grid ...
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1answer
49 views

GRASS Gis v 6.4.4. KeyError: 'version' when start

When I try to start the GRASS it gives me the following error GRASS 6.4.4 (Hellas):~ > ERROR: MAPSET Hellas - permission denied Traceback (most recent call last): File ...
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1answer
59 views

Error in executing commands in GRASS GIS

I'm using Grass 6.4.3RC2. I have a problem because when I execute the command: r.radcov csv_file=cell_list_hataDEM_umts_amc_testTEST.csv dem_map-AlbSRTMdem@PERMANENT clutter_map=AlbClut@PERMANENT ...
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1answer
53 views

How to import and layer stack seperate ndvi bands to grass gis?

I have 20 separate single band NDVI files. I have to import this into GRASS and stack them into a single 20 band image. How can I do that?
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0answers
37 views

How to load “soil types” in QGis?

I want to show soil transmissivity per pixel. Thus, I determine water holding capacity of each pixel (ignored other effective parameters). Respectively, I wonder, What is the soil data format and How ...
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3answers
1k views

Error when creating a new mapset with GRASS in QGIS

When I try to create a New Mapset with the GRASS plugin in QGIS I get an error or the program crashes. QGIS 2.6.1 (32-bit install, Win7). QGIS crashes completely when clicking "Finish" in the New ...
4
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1answer
197 views

How to calculate “water accumulated in each cell” using QGis?

I create channel network and catchment area from a DEM with SAGA GIS. I know that flow is starting from a cell to an other cell. Firstly, a cell is filled with water and then it is starting to flow ...
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0answers
57 views

Hydropower Calculation

I have assigned the elevation and the volume flow to each point at a river (with v.to.db and v.what.rast). Now I want to calculate the Elevation difference between each pair of points and then ...
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0answers
48 views

How to decide when flood started depending on the rainfall data?

I created a raster with the point values (mm) of rainfall data by interpolation in the raster menu. So I have a raster rainfall data and a DEM. With this rainfall data and a DEM corresponding to ...
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1answer
84 views

Calculate River Runoff Volume (Q) with GRASS

I want to calculate Hydropower between points at a River. I already created a Rivernetwork and the Accumulationmap (without weighting) with r.watershed. My next Step was to set equivalent points along ...
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1answer
37 views

How can I fill the category field in a raster using GRASS

I have a tiff file with land use data. The land use class in in the value field, but the label field is empty. Now I want to find out which is the area covered by each land use class, but GRASS does ...
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0answers
58 views

setting null values to 0 Landsat 8 Grass 7.1

I am working with Landsat8 images and need to run the albedo function in Grass 7.1.svn. In order to do this, I need to set the null values to 0 to eliminate the black border around the images. This ...
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0answers
29 views

automatic extraction of dtm using grass gis

i have generated dsm using erdas lps tool which is in img format. i want to import this file in grass gis and extract dtm. can you please tell me how to input the data , in which format it should be, ...
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1answer
129 views

Isochrone driving/public transport map : Grass or postgis?

I have to do Isochrone driving / public transport map. It would seem that the two better open-source solutions are grass and postgis. Could you tell me which one is the better? the easier to ...
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0answers
39 views

What is the background processing of rainfall thresholding?

I want to create a flood map using Quantum GIS. First of all I create catchment area (flow accumulation). Then, I delineate a Channel Network by applying a threshold to flow accumulation. So I want to ...
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1answer
76 views

tutorial for deriving solar insolation estimates from high resolution Digital surface model

I want to estimate solar insolation using grass gis. I have a high resolution DSM generated from Large Format Digital camera.Being a novice in this field i Would like to have a tutorial and steps to ...
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0answers
21 views

How to visualize insolation rasters over color orthophoto in grass

I have generated insolation time raster map using DSM, slope, aspect for day 100 and time 10.95 hrs using r.sun module in grass. The output insolation raster map (color table) i want to overlay on ...
2
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1answer
43 views

Looping for importing and interpolating a lot of LIDAR files?

I'm quite new to Grass Gis and I'm trying to make DEM (digital elevation model) for modelling flooding. I have 170 *.xyz files, which need to be scanned for extents (r.in.xyz -s input=...\filename.xyz ...
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1answer
63 views

How to change the Map Units in Grass?

because v.segment measures all offsets in map units, i have to change it. (I want to put all of 50 meters a point) So I checked g.proj -p: -PROJ_UNITS------------------------------------------------ ...
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0answers
35 views

problem with running raster calculator in grassgis

When I was trying to do NDVI with grassGIS I faced a problem. I cannot run the raster calculation. When I looked to the command console I see that (Sat Feb 21 12:41:58 2015) r.mapcalc ddes = ( ...
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0answers
28 views

Color polygon centroid according to attribute value in GRASS

I have many polygons in GRASS and want to color them according to their T-value. I can use v.colors and define a color table. That works fine when I plot the areas of the polygons. However, I would ...
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1answer
120 views

GRASS 7.1 (dev.) i.landsat.toar error

I am working with Landsat 8 image acquired in 2014. I am trying to convert the raw image (DN) to Top Of Atmosphere Reflectance/Radiance (i.landsat.toar) in Grass 7.1 (still under development). The ...
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0answers
41 views

Horton Stream Order as Category for r.fixed.segmetpoints with GRASS?

I'm working with Grass GIS. I want to use v.segment to set discrete, equidistant Streampoints (starting from each mouth). Since the water network is too large, it is impossible to define the rules ...
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1answer
37 views

How to change GRASS language within QGIS?

I use GRASS plugin inside QGIS on Japanese version of windows 7 x64. As I start GRASS tools, all the content show in English but when I try to execute a tool, tools option dispalys in Japanese ...
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2answers
103 views

Export GRASS raster as GeoTiff : nodata values exported as -nan (what happens in R?)

I am using the package raster to work with GeoTiff raster files which I expoerted from GRASS using r.out.gdal. GRASS assigned the value -nan to some raster files (type FLOAT32) for missing values. ...
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1answer
123 views

Export of group = multiband raster to another format not works in GRASS

I am really new in GRASS and my question is really basic but I dont realize where I am wrong. I have a set of single layers in my PERMANENT from some Landsat images (1 landsat = 7 one layer ...
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1answer
30 views

Overlaying of raster in GRASS for visualization?

I have generated insolation time rasters map in grass using r.sun module. How to overlay insolation time rasters over DSM depicting the color table for visualization?
2
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1answer
232 views

Can QGIS or GRASS convert layer files to shapefiles?

Should I be downloading QGIS or GRASS? I want the program with the most features. Most importantly, I have a lot of .lyr files. Can either of these softwares convert to shp and if so, how can I do ...
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0answers
36 views

GRASS GIS: Network analysis doesn't work correctly

I got a problem with the Network Analysis function v.net.iso in GRASS. I tried it so many times but the function doesn't work correctly. I tried to calculate isolines via the function v.net.iso, based ...
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3answers
74 views

Discrete Waterpoints with Grass

I've been working with Grass GIS for about two months. I have to develop a method for the identification of target regions of small hydropower plants. Boundary conditions are a predetermined minimum ...
1
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0answers
37 views

Raster Mosaicking GRASS Issue

I have a project where I have to download DEMs from USGS and mosaic them. So I downloaded them from EarthExplorer and imported them into GRASS. When I start the GUI version of r.patch using the ...
3
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1answer
483 views

GRASS GIS 7 in QGIS 2.6.1, Windows 7 64bit - Missing dependency

I am using QGIS Brighton 2.6.1. Today I have installed Grass GIS 7.0.0 RC2 to try its topology functions in QGIS. I have activated the provider, set the paths, but everytime I try to use any Grass ...
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0answers
115 views

Is it possible to generate a boustrophedon pattern which fill a vector Region with GRASS?

Every thing is in the title... I have a vector region in GRASS. And I would like to generate a vector (a polyline) beeing the bostrophedon pattern which fill this region. In the picture bellow, I ...
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0answers
15 views

r.watershed outputs different depending on use of console and toolbox

I am returned two different outputs despite same input parameters from r.watershed depending on whether I run it from the console or from the GRASS toolbox. The threshold for both is 5000. They both ...
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0answers
27 views

r.water.outlet returning blank raster

I am trying to delineate a watershed using r.water.outlet. I have created a flow direction raster using r.watershed (threshold = 50) (cell size is 300m). I use this flow direction raster in ...
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1answer
53 views

Draw lake isobaths having depth points and coast line

For some lakes, I have a line shapefile representing the coast line and some points with many information, among which depth (in meters). Is there a way to draw an isobath linking every point with the ...
1
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2answers
84 views

many add-on don't works GRASS 6.4.3

I use GRASS 6.4.3 on windows 7 64 bit. GRASS has been installed with QGIS 2.6.1. I have added r.stream.* adds-on by SVN. For each add-on, messages of installation were : OK. But when I try the ...
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0answers
35 views

I have an error when I execute a command in grass raplat

I use grass 6 in ubundu. I have putted the date into the .csv file and the antennas in .msi format, but when I try to execute the command in terminal "r.radcov" the system show me an error as: Error ...
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1answer
71 views

Raster import from GRASS to R - handling nan/NA

I have several doubts, so I will try to be as clear as possible... thanks for your understanding. I am generating a regression model using several environmental covariates. Before importing the GIS ...
0
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1answer
291 views

Grass 7 on Ubuntu 14.04. Can't start Grass

I attempted to install GRASS GIS 7 on ubuntu 14.04 using these instructions. When I call grass70 from the command line I get a welcome message and a prompt to continue. I then get two error messages: ...
2
votes
2answers
83 views

r.in.xyz doesn't work in GRASS

I have these LIDAR data *.xyz files (1st col x, 2nd col y, 3rd col z) 485000.16 6508997.48 1.84 485001.27 6508998.92 1.86 485001.02 6508996.68 1.85 485000.77 6508994.45 1.79 485000.52 6508992.19 1.79 ...
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0answers
56 views

Displaying a Digitial Elevation Model using GRASS GIS draped by an RGB Raster

I have the following: Digital Elevation Model from SRTM LANDSAT Imagery from the same area I wish to display the DEM draped with the raster band combination (3,2,1) using GRASS GIS. My ...
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1answer
53 views

Unable to find a specific GRASS add-on in QGIS

I would like to use the r.xtent add-on made for GRASS GIS (http://svn.osgeo.org/grass/grass-addons/grass6/raster/r.xtent/description.html) in QGIS using the GRASS plugin, but I can't seem to find it. ...
1
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1answer
67 views

i.landsat.toar doesn't Work With Band 6 of Landsat 7 in Grass 7

I'm facing an issue when running i.landsat.toar with a Landsat 7 image, here's the list of files: LE70010752014040CUB00_B1 LE70010752014040CUB00_B2 LE70010752014040CUB00_B3 LE70010752014040CUB00_B4 ...
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1answer
60 views

Calculate shortest path not on land but over sea

I wonder if someone can give me some advice on how to calculate the shortest path between two points, not over land but over sea. I know that I will have to take in to account the magnitude of sea ...
3
votes
1answer
120 views

It is possible to verify landsat reflectance values?

My question is really wide today, as I am still beginner in Remote sensing. I´ve asked a GRASS programmer to prepare for me Landsat reflectance values from raw DN values (1 scene per year from 1987 to ...
2
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0answers
53 views

3D interpolating

Our final year project domain is soil contamination modeling. We collected soil samples at the depths of 0.3 cm ,0.5cm , 1cm , 1.5 cm in about 25 locations. We considered 8 contaminants- p h, sodium, ...