Tagged Questions

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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0
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1answer
68 views

Raster image outside Grass screen, How to get it inside from start?

HI ALL: I'm new in Grass and need some help! I have created a LOCATION based on the coordinate system in which I want my data to be projected. So far I'm being able to Import & display the raster ...
4
votes
5answers
1k views

How to pansharpen LANDSAT 8 in GRASS?

Having used QGIS for quite some time for mapping, I was 'forced' to dig into GRASS as pansharpening is not directly executable in QGIS. After understanding more or less the structure, I did some ...
-1
votes
1answer
64 views

Is it possible to import/run AML script into GRASS?

I have an AML script that has instructions to import tmp files of (grid, network, basin...) is there any way to run the script in GRASS? I tried to converted to Python but I couldn't do it for the ...
1
vote
1answer
106 views

Use of Grass and R w.r.t. Land Use Prediction

In my data mining term project I need to conduct a work on geospatial data related to a big city to show possible urbanization fields in next years. I've used GRASS lately on other projects so I'm a ...
0
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1answer
258 views

r.basin.py GRASS addon

I have added this add on with g.extension on my grass 6.4.3RC3. But it doesnt work... this is the error I can see: Traceback (most recent call last): File "C:\Program Files (x86)\GRASS GIS ...
1
vote
2answers
172 views

Grass 6 extension installation in Grass 7 error

I am trying to install the extension r.roughness from the Grass 6 repository, but in Grass 7. When trying g.extensions, the error "make: * No rule to make target ...
1
vote
1answer
155 views

Add-ons on GRASS (win7)

Can someone help me to install an add-on for GRASS 6.4.3RC3, on Windows 7? I tried several approaches, but wasn't able to install the add-on. I found several topics here and on the web but the ...
0
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0answers
209 views

How can I calculate raster cell area for upslope contributing area

I am new to spatial analysis, and urgently trying to follow this tutorial to generate a topographic wetness index for my area of interest: ...
4
votes
1answer
287 views

R gridding and contouring options

I want to make an interactive web mapping application, which will grid and contour user data. My plan is to implement R scripts with Shiny, but the only R package I can find to do this is gstat. And ...
0
votes
1answer
134 views

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 ...
0
votes
2answers
490 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) ...
1
vote
1answer
219 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 ...
0
votes
1answer
199 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 ...
4
votes
0answers
215 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 ...
1
vote
1answer
1k 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 ...
0
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0answers
135 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 ...
4
votes
2answers
3k 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, ...
1
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0answers
114 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 ...
1
vote
2answers
138 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?
2
votes
2answers
962 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 ...
15
votes
2answers
5k 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 ...
3
votes
3answers
477 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. ...
0
votes
2answers
1k 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 ...
4
votes
1answer
480 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 ...
1
vote
2answers
122 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 ...
3
votes
1answer
209 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 ...
0
votes
2answers
187 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 ...
1
vote
1answer
53 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 ...
0
votes
1answer
161 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 ...
0
votes
1answer
36 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 ...
0
votes
0answers
275 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 ...
8
votes
3answers
874 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 ...
3
votes
2answers
2k 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 ...
0
votes
1answer
78 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 ...
0
votes
1answer
178 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 ...
0
votes
2answers
588 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? ...
1
vote
1answer
79 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 ...
0
votes
1answer
385 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 ...
3
votes
1answer
839 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 ...
1
vote
1answer
433 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 ...
1
vote
0answers
381 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 ...
0
votes
2answers
181 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 ...
3
votes
1answer
110 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 ...
0
votes
1answer
74 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, ...
2
votes
2answers
445 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
votes
0answers
99 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)?
4
votes
2answers
237 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
votes
1answer
108 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 ...
2
votes
1answer
320 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
votes
1answer
124 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 \ ...