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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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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268 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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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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326 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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106 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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94 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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656 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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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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372 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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489 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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401 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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298 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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315 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 ...
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119 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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86 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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81 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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341 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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778 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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80 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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268 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
176 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 ...
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145 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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147 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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116 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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135 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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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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199 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 ...
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839 views

How to combine polygons in a vector with GRASS?

I need to combine polygons of similar geological classes which are stored in a vector file called geology. I was looking for somethiing like "union selected features" or similar. In the GRASS Book ...
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177 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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70 views

Extract representative slope profiles from hillslope polygons

With the help of the Whitebox Geospatial Analysis Tools I was able to easily extract hillslopes from a river network in combination with a flow direction map. Now I would like to extract ...
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22 views

execute binary from grass shell?

I am new to grass and could really use some help with my problem. I am using hydrologic modeling software, and it include a grass program that I need to run from the grass shell. My question is, how ...
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31 views

Error message retrieval in grass.read_command

I am writing a script in python and would like to get the error messages of the function grass.read_command for seeing why it is not working. I found a webpage ...
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52 views

Option for 360 degree movie embedded in Open Source GIS software?

Is there any Open Source GIS software available to embed 360 degree movies with the map? For a COTS example, there is the Active Link Vision (ALV) extension for ArcGIS from IWANE.
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54 views

Why GRASS 7.0.0 can't create a table while importing shapefiles from QGIS?

I use GRASS7.0.0Beta1 and QGIS 2.4.0 on Windows8. With v.in.ogr, when I import a shapefile, I get the error message "Unable to create table". When I put the option of not importing the table, the ...
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87 views

IS it possible to run GRASS commands in the QGIS graphical modeler?

I have a geoalgorithm set up in the graphical modeler and everything runs except for the GRASS commands. It is really frustrating because when I execute these commands on their own they work just fine ...
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423 views

Solar irradiation calculation using r.sun

I am trying to compute the global solar irradiation for a region and the run times seem to be a bit too high. I have as inputs a Digital Surface Model with the buildings and a Digital Terrain Model ...
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161 views

GRASS v.rast.stats missing in sextante toolbox

I am new in the QGIS world and also with GRASS. I am really interested in using v.rast.stats as is doing exactly what I need. My problem is that I am not able to find it inside sextante in QGIS and I ...
3
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1answer
120 views

Wrong direction in r.watershed slope length calculation?

Or have I completely misunderstood something now? As a programmer I took it for granted that the row number would change if I traversed the map up and down in the program along the North-South axis ...
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265 views

Hand fit curve and then apply to time series of rasters, make a map. How?

Maybe a data management problem, not too sure, but likely a challenge which someone has dealt with before. I have a time series of rasters. I can summarise the information by taking averages of each ...
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3answers
539 views

Problem with v.in.ogr.qgis in QGIS

I received a shapefile containing data from a topographic survey of a farm. The file has a lot of lines containing elevation data. The person who made the survey did it with a GPS set up on a ATV. ...
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2answers
502 views

How to single out country data from a world data map?

Say that i have two "data sources"; A global map of average wind speeds, A shape file (or similar information) of all country borders in the world. How do i combine these two sources and extract ...
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99 views

How calculate pixel by pixel the mode (statistic) of multiple rasters (geotiff)?

I have 12 land cover maps, and I would like to calculate the mode to each pixel of the 12 maps (they have the same resolution and dimension). I mean, the final map would be the mode for each pixel of ...
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1answer
1k views

How to identify line intersection in QGIS when I have more than 2 lines?

I am trying to identify where overlaps exist between multiple shapefiles. I would use the intersect tool, but it only allows me to intersect two layers. I have over one hundred individual line ...
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1answer
195 views

Combining Geological Grids and extruding between them?

I have a situation where I have 3 Geological grids, each showing a different horizon + the Seabed Grid. I need to extrude between these grids in order to make the 3D polygon for the geological ...
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3answers
2k views

Viewshed / Line of Sight analysis- as a batch process?

I wish to carry out a line of site analysis similar to the subject in here (preferably within QGIS): Visual Impact Assessment in QGIS or GRASS Scenario: I have two points, A and B. Point A is a ...
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392 views

How does GRASS handle multi-channel images (e.g. landsat)?

I am trying to understand how to use multi-channel images (e.g. landsat or the land-cover data provided by Natural Earth). I am hoping that someone can confirm or correct my interpretation of the ...
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2answers
1k views

saga & grass configuration in sextante (ubuntu)

I have some trouble in running saga and grass algorithms in sextante. When I double click it appears a pop-up saying: Missing dependency.This algorithm cannot be run :-( This algorithm requires SAGA ...
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1answer
1k views

GRASS Geoprocessing in Python Script

I´m trying to get some GRASS geoprocessig tools running in a python script outside GRASS. I´m able to import grass.script, but I´m not able to get the tools running yet. Does anybody know what I´m ...
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122 views

GRASS 6.4.0 and GRASS 6.4.SVN

What is the difference between GRASS 6.4.0 and GRASS 6.4.SVN? Thanks
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58 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 ...