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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908 views

How to cluster Raster data

I have thousands of Raster data concerning the ice coverage at the pole at different times (days) over several years. Now I would like to perform a cluster analysis. I want to split the data into ...
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695 views

How to clean layers from non topological databases?

I'm doing my internship in a consulting office which is switching from MapInfo to QGIS/GRASS 1.8.0. I posted here a few days ago about the way to clean a polyline from a Lidar data with v.clean. ...
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1k views

How to split line at a specified distance and getting coordinates of start and end points of each line segment?

I tried v.split in GRASS: and my notebook ran a lot of time but showed this error:bad allocation, then I click "OK", and got nothing. Are there other ways to split lines?and I hope to get 2 new ...
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145 views

Temporal GRASS GIS framework

I am trying to follow the tutorial posted here. When I get to this part "Extraction of seasonal mean temperature" and run this code: t.rast.extract \ input=temperature_mean_1950_2011_seasonal \ ...
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162 views

v.dissolve to multipolygon

Using v.dissolve in GRASS, I'd like to get a multipolyon as a result. However, I end up with distinct polygons with the same 'dissolve value.' For example; lets assume I have two polygon features ...
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113 views

Is there an easy way to taper huge amounts of drainage vectors?

I've performed hydrological analysis using r.watershed using GRASS and now I have some stream vectors for a large area. Next, I'm planning to taper these streams to varying width to make them appear ...
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512 views

How to reproject a raster to Winkel Tripel projection?

I'm trying to project a raster map (in ASCII grid format) from longlat to the Winkel Tripel projection. But I'm running into errors, for instance gdalwarp won't accept the proj-string. $ gdalwarp ...
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587 views

Where to change GRASS GIS wxGUI language?

I use GRASS 6.4.2 on Russian version of Windows 7 x64. As I start wxGUI it is shown in Russian. But I don't like its translation and want to work with English interface. I have no clues how to solve ...
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557 views

spgrass6 and GIS_LOCK

I would like to thank's everyone first, i learn a lot here (gis.stackexchange) about GIS. I have one question about the use of GRASS within R session, i'm able to do some basic task, but i have one ...
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1k views

Is there a way of cutting a raster map that is displayed in the GRASS GIS Map Display?

I have a raster map that I generated from cropping/masking from a bigger raster map. It produced a map with only a portion of not null values. I only want to have a map that is zoomed in to the ...
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54 views

Is it possible to have v.in.lidar without compiling GRASS?

I already have installed libLAS like this: sudo apt-get install liblas-bin And Ì have installed GRASS GIS 7 from the ubuntugis-unstable repository. Is it possible v.in.lidar without compiling ...
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33 views

QGIS Convert bathymetry shapefile from fillable to strokeable

In Java I would like to stroke the bathymetry depth lines instead of filling the area. I'm starting with the Natural Earth Bathymetric Data: ...
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36 views

Simplify / generalization of flow lines

I'm trying to make a model of surface runoff of rain water. I'm using GRASS GIS function r.flow, which generates nice smooth lines of runoff. What I need is edit these flowlines someway to avoid ...
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1answer
88 views

To make a map of sinkholes on grass gis

I would like to make a map of sinkholes. I have a DTM ARC/INFO ASCII GRID of Asiago Plateau and and I'm using grass gis. Does anyone know what is the correct form in grass gis?
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2answers
187 views

GRASS GIS not starting

Hello my name is Luca and I write from Italy. I have a problem with GRASS GIS 6.4.3. Last week I installed QGIS 2.4 with GRASS GIS 6.4.3 GUI on Windows 7 64 bit - admin user. When I click on GRASS ...
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1answer
294 views

Pan sharpen Landsat 8 using Grass 7

I have followed this great tutorial on pan sharpening using Grass GIS 7 (I'm using beta 3). Everything in the tutorial seemed to have worked, but my final output is not as expected (pictured below). ...
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444 views

Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
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329 views

NVIS module not found in QGis

When I try to use the nvis module in Grass, QGis, pops-up a warning window saying "Module nviz not found". how can I solve this issue and use the nviz?
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2answers
304 views

Select polygons that do not intersect any other polygon using QGIS, GRASS, SAGA or R

I would like to select the polygons of the layer below that do not intersect with any other polygon (within the same layer). How can I do this using QGIS, GRASS, SAGA or R?
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251 views

How to import ESRI Ascii format into GRASS?

I need to take a set of datafiles, generated by our sensor system that reads GPR (Ground penetrating Radar) deviations over a surface as we drive along. I have discrete readings from a set of sensors ...
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1answer
3k views

How to find the watershed area for each point in the river network using DEM?

Update#1: Thanks, Micha, I have followed your instruction and successfully use the modules in GRASS. I use r.watershed to get the basin raster and the drainage line: and I use r.water.outlet to get ...
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334 views

How to get started with GRASS shell?

I'm a beginner in programming but i have to work with GRASS at work, and do it quickly. I'm completely lost with all the variety of tutorials that are existing and to me, don't look the same...and ...
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368 views

Hydro-Enforced/surface constraint DEM Creation using GRASS/QGIS

I am wondering if there is a way to create a hydro-breakline enforced DEM by means of any open source solution? I am able to create a DEM from Lidar data using GRASS, but would like to enforce some ...
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1answer
127 views

GRASS r.grow doesn't seem to change raster values at all

I have a raster map in GRASS that looks like this: The red cells have a value of 1, the yellow cells have a value of 0. I am trying to use the r.grow command to 'fill in' the gaps in the red ...
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103 views

V.kernel not working correctly in grass-6.4.2

I am using grass-6.4.2 for generation of heat maps of crime data. For testing purpose, I created a vector layer from my places shapefile which is a point data.The places shapefile contains more than ...
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1answer
734 views

r.watershed analysis error from raster map being in different zone and unable to be opened

I tried running my DEM (geotiff) file through the r.watershed program by the GRASS GIS plugin of QGIS. I believe the error message results from a raster map in the different zone than the current ...
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2answers
2k views

How to perform volume calculation in QGIS

EDIT 07/12/12 Ok, meanwhile I came to another problem I want to discuss. I just tried around with the volume calculation with some layers and came to a point where I receive the following error. ...
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2answers
399 views

run r.stats as a quiet module in GRASS-Python script

Has anyone else used r.stats as a quiet module in a GRASS-python script? As part of my program I'm using: grass.run_command("r.stats", flags='l', input=<file>, output=<*.csv file>, ...
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534 views

How to make a transparent background image using r.out.png?

Can the white background of the r.out.png of GRASS be changed to transparent?
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424 views

Standard Colors for Landcover Maps

I have classified Landsat images into five classes - A variety of Palm, Water bodies, built-up/open area, other vegetation and miscellaneous. I used GRASS GIS for the process and the final classified ...
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1answer
324 views

Problem in r.resample

When I run r.resample to crop a map by using a vector and a mask, the resulting map has the same shape as the vector that I used but does not replicate (exactly) the portion of the raster map that I ...
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39 views

How can I change the way r.cost and r.drain modules work?

Look at the picture #1. This is my cost surface raster that has only 2 values. Area restricted for path to cross (red one) and area that is free to go (yellow one). As I need it and as I undestand how ...
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2answers
95 views

Loading Grass 7.0 vectors in QGIS broken?

Running QGis 2.8.1 in Win7 (64bits), installed through OSGEO4W. When trying to load a Grass 7.0 vector file in QGis, the program will simply crash without any notice. I can load old Grass vectors ...
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1answer
544 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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1answer
174 views

ArcGIS Desktop equivalent to GRASS r.geomorphon algorithm?

I would like to know if in ArcGIS Desktop 10 there is some tool/algorithm which can be used to perform the same analysis that r.geomorphon does in GRASS 7.
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113 views

Merge different Landsat scenes in Grass GIS

I am new to Grass GIS, and I really need some help in solving this issue. I have 17 scenes from Landsat8 covering an area. I have created color infrared images of bands 5,4,3 and now I want to merge ...
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1answer
103 views

Underwater terrain modeling

My task is to model the surface of a lake bed, calculate volume of it and visualize it as 3D a surface. I have acquired depth measurements in a small lake using echosounder. The precision should be ...
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1answer
404 views

how can i correct atmospherically landsat 8 images?

I am trying to correct atmospherically an image from Landsat 8 with 6s model from grass 7 and 6.4. Because there are no parameters for Landsat 8 yet, I am trying to give parameters from Landsat 7 ...
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2answers
581 views

How do I reproject one raster to match another's in GRASS

I have two raster layers, A and B, which have information about the same location but have different projections and datums. How can I reproject layer A to match the projection and datum of layer B? ...
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2answers
245 views

Issue while running grass from subprocess

I have a map based web application using geodjango. I needed to display the crime hotspots within a selected polygon area. I found that v.kernel is very good for generating heatmaps/hotspots. So in my ...
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1answer
999 views

How do I use the GRASS command line tools within QGIS?

How do I use the GRASS command line tools within QGIS? I use the QRASS plugin to open the mapset, and then I open the GRASS tools window. I click on 'GRASS shell' under modules and it brings up a ...
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1answer
89 views

What defines a Class in the Heat map plugin?

What defines a Class in the Heat map plugin? As in: "Black holes like that are usually caused by raster values exceeding the range of the color ramp. Try adding another class with a higher associated ...
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1answer
298 views

How to prepare road network for routing in QGIS or GRASS

I have been working on a road network and I want to run shortest path algorithms on it. One problem is that some lines come very close to each other, but are not connected. Is there a way to connect ...
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2answers
192 views

Is r.cost equivalent to diffusion interpolation with barriers?

I want to perform interpolation using cost distances rather than euclidean distances similar to Greenberg et al. (2011). In that paper they use r.cost in GRASS to compute cost distances for each ...
3
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1answer
149 views

Issue with Sextante r.map calculator and modeler

I am trying to build a model with Sextante modeler and the r.mapcalculator algorithm but when I run the model I get the error message: ‘Could not load layer: ‘….’Check sextant log to look for errors ...
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1answer
167 views

Showing map in Grass Layer Manager/Map Display via Python

I've created some raster(tif) maps using Grass libraries in Python. I want to opem them automatically in Grass GIS Map Display or Layer Manager after creation. I don't want to use GUI for this. What ...
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1answer
126 views

How to recategorize features in GRASS by geometry, like the ArcGIS Sort tool?

The ArcGIS Sort tool creates a new feature class with features sorted by geometry. For example, it can number features IDs from north to south, etc. Is there a way to renumber the cat field in a GRASS ...
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1answer
137 views

Creating rasters?

I am doing my masters in archaeology, but have used GIS for some time now, however this is my first attempt at generating and using rasters. I appear to have been successful for some, but not so well ...
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2answers
1k views

How to vectorize a Raster-Classification? (qgis, grass)

I classified my raster-DHM into elevation levels using colormap. Its not a "real" classification, just a colormap. So I cant vectorize the classes to get polygones for every class. Whats the best ...
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2answers
244 views

How to make the layer 2 use the same vector categories from layer 1?

I'm having some doubts concerning the layer mechanism. Creating a new layer (ie a new connection between a vector and a DB table), I've imported a vector (rivers) through v.in.ogr, then I've cloned ...