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.

learn more… | top users | synonyms

3
votes
1answer
105 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
71 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
391 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
87 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
224 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
102 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
256 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
110 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
votes
2answers
302 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? ...
0
votes
3answers
681 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 ...
3
votes
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 ...
1
vote
1answer
146 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 ...
0
votes
0answers
168 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... :( ...
0
votes
1answer
85 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 ...
3
votes
2answers
171 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 ...
1
vote
1answer
180 views

Data management in GRASS from command line?

I'm trying to import a large set of raster files into GRASS. The GUI import tool works fine for a handful of files, but it appears to require that I click the "Layer id" checkbox for each individual ...
0
votes
1answer
35 views

Why is this GRASS script (from GRASS WiKi) causing an error?

I'm trying to run a script from the GRASS WiKi to create a simple map using ps.map. I'm confused because it's generating an error that the output was not set, when it appears to me that it is set at ...
0
votes
2answers
220 views

Error from ps.map in GRASS. How to fix?

I'm trying to learn how to use ps.map in GRASS. I thought that running it in interactive mode from the command line would be a good place to start, but I'm getting the following error: > ps.map ...
1
vote
1answer
373 views

How to invert polygons (or other options for exterior styling)?

I have a shapefile containing many polygons that I want to use to mask a raster. I have tried gdalwarp -cutline <shapefile> -crop_to_cutline -srcnodata -9999 -dstnodata -9999 ...
2
votes
3answers
348 views

How to batch-process georeferencing of rasters (prelude to animation)?

I have many (10k) raster files, all with identical size and pixel dimensions, which need to be georeferenced. I would like to georeference one of them manually, using either QGIS or GRASS, and then ...
0
votes
0answers
59 views

Why don't libgrass.so.1.8.0 and libqgissqlantconnection.so.1.8.0 load?

I have compiled Qgis 1.8 at Ubuntu 12.10, but some phyton plugins does'nt work, like sextante. Trying to solve this problem, some files don't have been load. They are: libgrass.so.1.8.0 and ...
2
votes
1answer
78 views

Is it possible to use a WHERE clause with Grass v.in.ogr for DGN sources?

I am trying to import a .DGN with Grass v.in.ogr in QGIS. I am able to import the DGN perfectly, but I would like to filter the elements using the WHERE option. From searching, reading and testing I ...
2
votes
1answer
67 views

r.neighbors produces no output

I am running r.neighbors --overwrite --verbose input=bf03pits@PERMANENT output=bf03pitsdenoise method=mode size=5 in the GRASS GUI using the r.neighbors dialog. bf03pits has 3955848 all with ...
4
votes
3answers
379 views

query raster cell values by point

I have a binary raster (0s and 1s) that I need to query given a set of point coordinates. This is easy enough to do with gdal (gdallocationinfo), but where it get's complicated is that I also need to ...
2
votes
1answer
392 views

Grass v.clean.snap with Polygons

I am doing some topology testing using Grass in QGIS. I am hoping to snap nodes to eliminate gaps between polygons. When I use the v.clean.snap function in Grass it does not work on polygons. When I ...
4
votes
1answer
299 views

Topology problems with QGIS/GRASS

*edited file links below I'm working on several NGO projects at the moment, all of which are reliant on being able to use a district level map with some 490+ features, and I am running into some ...
0
votes
2answers
76 views

How to align directions of connected lines?

I have a vector line made of different pieces of lines with different directions. I merged the lines to one. But this merged line still have different direction in its "invisible" parts. I want to ...
1
vote
1answer
134 views

How to begin with tool development for GRASS gis or QGIS GRASS

I wanted to begin with customized tool development in Grass GIS or QGIS grass. How should i begin in to develop the tool. I search a lot in google search engine for begin with tool development in ...
2
votes
1answer
102 views

GRASS : r.resamp.rst error : “Not enough disk space--cannot write files”‏

Today, I am confronted to a difficulty I cannot manage. When I try to use the tool "r.resamp.rst", it gives me as answer: *r.resamp.rst input=map@PERMANENT ew_res=11 ns_res=11 pcurv=curv ...
2
votes
2answers
157 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 ...
1
vote
1answer
248 views

Rasterize vector with gdal

"I would like to calculate the Euclidian distance from a residence to a public service of interest e.g. the distance from a residence to a green space (as the crow flies) in QGIS. After browsing the ...
4
votes
1answer
159 views

Programmatic raster-vector calculation

I currently use GRASS' r.mapcalc to find the difference between vector and raster data using a loop and temporary files and layers. Is it possible to do the core calculation between raster with a ...
2
votes
1answer
67 views

grass gis- ERROR: nwalk (7000001) > maxw (7000000)! [closed]

i want to make r.sim.water (hydrological modelling) in Grass Gis, and this ERROR: nwalk (7000001) > maxw (7000000)! always appears, any ideas how to solve it? number of cells of dem is below 7000000. ...
0
votes
1answer
442 views

QGIS, Euclidean distance analysis [duplicate]

i wanna generate euclodian distance map for my road data. I 'll use it for multi criteria analysis. I can get it by using Arcgis Euclodian Distance tool but i wanna generate it in QGIS environment. I ...
2
votes
0answers
26 views

How to remove coastlines from Admin 0 data set using GRASS?

I have a set of international borders that I would like to overlay on top of a different data layer that represents coastlines ("land" essentially). I would like to convert my Admin 0 polygons into ...
1
vote
3answers
143 views

How do I active “Open GRASS tools”-button?

I have opened to GRASS layers and need to use the "Open GRASS tools"-button. This button remains unactivated somehow. Whilst the "Edit GRASS vector layer" right next to it works perfectly fine. What ...
4
votes
2answers
203 views

How to do a looping to Interpolate a huge Rainfall Time-series in GRASS GIS or R

In GRASS GIS I have access to a table in PostgreSQL Database with this structure: Table Name: rainfall_time_series Columns: id | year | month | day | value_mm | x | y | gauge_code Setting g.region ...
2
votes
1answer
450 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 ...
3
votes
1answer
65 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 ...
1
vote
0answers
156 views

Heat Map trouble: Is this a data formating problem?

I'm playing with the heat map plugin with QGIS. I've run through QGIS tutorial: http://docs.qgis.org/html/en/docs/user_manual/plugins/plugins_heatmap.html, using the airports data set as explained ...
3
votes
2answers
93 views

Is there a workaround for GRASS i.maxlik 'class' being a keyword in Python?

I am running i.maxlik in python - attempting to automate a processing chain. I use the command: grass.run_command('i.maxlik', group= group, subgroup=subgroup, class='classification', sigfile = ...
3
votes
1answer
244 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 ...
0
votes
2answers
370 views

How do you use 'reclass' in GRASS?

It could be user error, but for some reason, the reclass tool is just hanging and hanging... QGIS 1.8 Compiled against GDAL/OGR 1.9.2 Ubuntu 12.04.1 Running the tool from the Sextante toolbox Input ...
2
votes
1answer
825 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 ...
0
votes
1answer
66 views

GRASS v.db.update Concatenate Fields

I am trying to concatenate two fields into one new field in GRASS, but I am unable to get the syntax to work. Ideally, I would like "FIELD1" and "FIELD2" concatenated together in "FIELD3". All fields ...
0
votes
0answers
108 views

GRASS i.landsat.toar returns empty raster

I am trying to use the GRASS module i.landsat.toar. Currently the files created are empty and it spits out: So it seems that it is not picking up something? The location is set to the extent of ...
3
votes
1answer
230 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 ...
3
votes
2answers
147 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 ...
4
votes
1answer
223 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
1
vote
1answer
133 views

How to remove terracing from Civil3D GeoTIFF export?

I've received a GeoTIFF DEM that was exported from Civil3D and at every contour there is a distinct terrace created when I process an aspect or slope in QGIS with the GRASS plugins. I've looked ...