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 setup and use GRASS?

Previously I've asked an question and Micha gave me a helpful advice:How to find the watershed area for each point in the river network using DEM? After getting the useful DEM file, I began to setup ...
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310 views

3D Interpolation using point cloud in GRASS GIS

I've imported a set of 3D points (z,y,z) into GRASS GIS. I'm having trouble: a) visualising my dataset in 3D using nviz or the standard data viewer (I can only get a 2D plan view of my data) and, b) ...
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145 views

how to loop grass command in python and put variable in output file

anyone, first day Grass programming with python scripting; first prob; simple I want to reclass the same raster several times; and save the file with the value loop variable at the end ... can not ...
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87 views

How to estimate distance from points to line feature with v.distance?

I'm trying to use the v.distance module in GRASS 6.4.3 to estimate the distance from a series of point features (animal tracking locations) to the nearest point along a line feature (a coastline). I ...
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178 views

How to create a topologically correct dataset in PostGIS (with GRASS)?

I have shapefiles which I have loaded in postgis and now i am trying to use geometric function in postgis like ST_intersect and they fail because the data is not topological correct. I have tried to ...
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643 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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40 views

GRASS - Creating an Attribute Based on Driving Distance

Is it possible to calculate the driving distance for each node of one layer (fire stations) to each node of another (address points)? After doing so, I need to sort all of the distances from shortest ...
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113 views

Grass won't import shapefiles

I have a problem involving the import vector data command, specifically importing shape files. I installed QGIS on a pc at work and there I could import shape files into GRASS GIS 6.4.3RC2 (which is ...
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1k views

How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
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87 views

GRASS v.overlay.or Error when trying to split a polygon with a line

I am using the Grass plugin in QGIS for Windows (1.8.0). I am trying to split a polygon with a line feature. I am using the v.overlay.or function within the QGIS Grass plugin. I have the line layer ...
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2answers
106 views

contour lines from point shape attribute

I have a point shape file and one of the attribute refers to the altitude. Is is possible to obtain a contour lines shape file in GRASS?
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160 views

SEXTANTE “could not load layer:…”

When I try to do a GRASS command via SEXTANTE in Qgis I always get the error: "Could not load layer:...." check log file Does not matter wether it should be saved in temp or another folder. I found ...
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570 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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2answers
3k views

What's the relation between QGIS and GRASS?

I have been working with GIS and remote sensing in an university and professional environment some ten years ago (ArcInfo etc), so I have some experience even though somewhat outdated Right now I am ...
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3answers
332 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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670 views

How to resolve missing Python module (importlib) for GRASS/Sextante?

I have installed the nightly build of QGIS 1.9 from Larry's Dakota Cartography site, and have downloaded the latest Frameworks from William's Kyng Chaos site. However, I am unable to install the ...
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357 views

How to repair and clean contours from high data resolution (lidar)?

I'm unsuccessfully trying to make a bathymetric map with contours extracted from Lidar data at 1 m resolution. The extracted contours have a lot of artifacts like dangles and islands. First I used ...
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116 views

r.regression.multi - ERROR: Not enough valid cells available

I am running a few analyses with r.regression.multi in Grass 7. For a few rasters that I try to correlate, the following error comes up, however: "ERROR: Not enough valid cells available". I cannot ...
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143 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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140 views

GRASS: populating attribute table with specific values

I have a vector map that includes 100 points. These points were created using v.extract to randomly sample a larger map of 10k points. As such, the 'cat' values range from 1 to more than 10k. What ...
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44 views

GRASS: shift point locations in a random direction

I have a vector map that contains 100 points. For each point, I would like to shift it 250 units in a random location. It's easy enough to shift all points in a specified direction using v.edit ...
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112 views

Problem opening GRASS GUI: libgeos-3.3.6.so: cannot open shared object file:

I have been using GRASS to process some Landsat imagery but very recently, and as far as I am aware - after having done nothing different or changing the settings, I am trying to use GRASS and on ...
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32 views

GRASS GIS: red square around node topology information?

I've been using GRASS since 2005, but I cannot find an explanation to the square boxes that appear around the nodes of a lines layers, when I display topological informations on the map. I thought ...
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189 views

HELP! Starting up GRASS - Error messages.

I am just trying to start using GRASS, but am having problems setting up. This is the error message I get: WELCOME TO GRASS Version 6.4.2 2012 1) Have at your side all ...
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616 views

Howto setup and use a remote GIS workstation (QGIS,GRASS,PostGIS)?

I'm using QGIS (and sometimes GRASS and PostGIS) on my 2009 MacBookPro for my thesis project. I was wondering (during an endless batch generalizing in QGIS) if I can set up a server so I can work from ...
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809 views

How to reclassify a float raster?

I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
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60 views

Full Easting and Northing coordinates values cannot be encoded in GRASS r.water.outlet in SEXTANTE-QGIS

The Easting or Northing coordinate parameter accepts only 5 digits. The Easting and Northing values for my outlet are 6 and 7 digits long (integer). How can they be encoded in r.water.outlet? Can ...
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151 views

Sextante grass folder incorrect?

What is the correct grass folder in Sextante? I alway get this message: The specified GRASS folder does not contain a valid set of GRASS modules. Please, go to the SEXTANTE settings dialog, and ...
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430 views

Grass 7 / ArcGIS 9.3 - tiff to raster

Again a Grass 7 question. I have the output of a modelling run as matlab file, which I can export as tiff and load as geotiff. OK - now can I extract the data/convert this tiff into a raster proper? ...
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74 views

Grass7 - r.regression.multi and new raster

I am on the learning curve with Grass7. I managed to make r.regression.multi work, but there is one thing that would be of high interest for me: it is possible to create a new raster showing the ...
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188 views

qgis plugin: “WindowsError: [Error 6] The handle is invalid”

OS: Windows 7 64bit GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe) path variable: GISBASE=C:\Program Files (x86)\Quantum GIS Lisboa\apps\grass\grass-6.4.3RC2 ...
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580 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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309 views

import grass.script as grass under windows 7

OS: Windows 7 64bit GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe) I have created a plugin for QGIS, with the QGIS plugin builder. Now i would like to import grass.script into ...
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262 views

GRASS Plugin to QGIS error

I am installing QGIS and GRASS as part of an FOSS GIS class I'll be teaching this summer. I used the OsGeo4W installer. This installer has always worked flawlessly for me except on the machines at the ...
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160 views

Handling MODIS NoData cells with gdalwarp

I'm using the gdalwarp tool to convert MODIS .hdf into GeoTiff files. I want to set the value of the nodata cells so that when I import the .tif image into Grass there is no black edge. I'm using the ...
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1answer
97 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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1answer
67 views

Grass 7 - where is r.regression.multi hiding?

I compiled Grass 7 on Ubuntu and all works fine - except, I cannot find r.regression.multi. I installed it, yet it is nowhere to be found in the drop-down menus; r.regression.line is there and works, ...
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2answers
337 views

Flow modeling and FOSS GIS; lahars and HEC-RAS

What are the options for FOSS flow modeling of dilute debris flows in QGIS or GRASS? Have you, or can you refer me to studies where the authors, tested these models/plugins/functions/etc. for use in ...
2
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0answers
78 views

How to create the fuel models & live fuel moisture rasters for Wildfire simulation?

Has anybody done wildfire modelling in GRASS? Where could I obtain / how do I create the fuel models and live fuel moisture rasters to determine rate of spread (r.ros)?
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2answers
197 views

Autocorrelated DEM with QGIS or Grass

I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
2
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1answer
96 views

Help with GRASS V.Net.Path

GRASS has extensive and brilliant documentation, but I still have a bit of trouble using v.net.path. in the example for shortest path, it says: " #Shortest path: ID as first number, then cat1 and ...
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1answer
192 views

How to join nodes to network lines ( and not the other points)

I'm trying to do a shortest path analysis on my network. In order to prepare the network and attach polygon centroids to the roads, I used GRASS' V.NET operation=connect. the problem with this ...
2
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1answer
104 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 \ ...
2
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2answers
239 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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478 views

How to rasterize a vector map?

I am looking for a way to create a raster grid from a vector map. I have a map consisting of shapefiles which I want to export as a raster with UTM coordinates. I was thinking of something using the ...
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1answer
1k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
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134 views

Grass 7 .las data import problem

I compiled Grass7 on Ubuntu 12.10, with liblas in order to run r.in.lidar and v.in.lidar. I now want to import .las data; the option in file -> import raster data -> LAS LIDAR points import is given ...
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154 views

Help in GRASS/QGIS/Python

I have Idea about ArcGIS, and a bit of QGIS and zero programming knowledge, which I am trying for thesedays. I saw GRASS GIS and have started working with shapefiles, which are not being loaded... :( ...
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81 views

Why can't I load more than 12 elevation files into NVIZ?

I have a large set of rasters in a GRASS mapset, which I would like to use as frames in an animation, visualizing the raster data as elevation. NVIZ is an obvious tool for this, but I'm having trouble ...
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2answers
156 views

How do I tell GRASS where to find Python?

For some reason, when I start GRASS on my Mac it says that it has found Python 2.6.7. However, /usr/bin/python version is 2.7.2 and I can't find a lower version anywhere on my system. Potentially ...