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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42 views
Add GRASS Addon to Sextant within QGIS
I have successfully installed r.viewshed as an add-on in GRASSS 6.4.2. I would like the command to show up in the list of algorithms within Sextante. Is there a way to make Sextante "aware" of ...
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0answers
48 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
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1answer
48 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
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1answer
33 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 ...
3
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3answers
100 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 ...
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1answer
96 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 ...
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116 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 ...
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2answers
46 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 ...
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0answers
72 views
Free and Open Source GIS Desktop Dissertation Survey – Participants wanted [closed]
I am currently in my last year of MSc Information Technology course at the University of the West of England. I am required to undertake a dissertation project. I am conducting a study on the level of ...
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0answers
42 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
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1answer
66 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
...
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0answers
27 views
Why are there strange black and white rows and columns in my aspect map?
I would have a problem with aspect map in GRASS. I'm not an expert, so I think you easily can help me. I have created this aspect map, from dtm, but the result was an image with strange black and ...
2
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1answer
62 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
152 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 ...
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0answers
87 views
Export to shapefile qgis
I am trying to develop hotspot map showing point density in our gis based web application. After searching for an option I have decided to use v.kernel command. I have a table containing some point ...
4
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1answer
84 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
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1answer
38 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.
...
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1answer
106 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 ...
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17 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 ...
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3answers
57 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
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2answers
86 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 ...
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1answer
132 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
36 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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0answers
83 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
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2answers
57 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
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1answer
100 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
106 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 ...
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1answer
193 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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1answer
33 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 ...
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51 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
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1answer
111 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 ...
4
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0answers
52 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
134 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 ...
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1answer
82 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 ...
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1answer
33 views
GRASS: Loss of data using v.net
I'm trying to build a network in GRASS in order to find the shortest path from any settlement out of 1120 (points), to one waste treatment facility out of 27 (points). I plan to use v.net.distance ...
3
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1answer
100 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 ...
4
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3answers
162 views
How to install GRASS on Linux Mint?
I'm trying to figure out an error in GRASS network analysis, for several days now. I started to suspect that it has something to do with my OS, namely Windows 7. Hence I installed Linux-Mint 14 ...
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0answers
58 views
GRASS python script runs twice
Is there a reason that every script I have written for GRASS in python runs twice? I start them using the GUI script launcher tool, and they all begin with:
#!/usr/bin/python
import grass.script as ...
1
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0answers
81 views
How to handle/ avoid intersect errors when clipping the difference between two layers?
Using QGIS + Grass, I've added a shapefile of coastline and islands to my map.
I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
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0answers
209 views
How to resample a raster in QGIS?
I've got a boundary file that I would like to resample the raster file from a 30m grid to a 10m grid inside the boundary file. When I try and do it in Qgis or Grass all I get is one big raster cube ...
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2answers
61 views
Error using Grass v.net
I'm trying to connect my network to a points layer with a threshold of 4500 meters. I have about 11000 or so entries in my polyline and about 24 in my points layer.
I have alreday used v.distance, ...
1
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1answer
192 views
Installing GRASS on MINT 14?
I'm very new to mint/linux/GRASS and have no clue how to deal with these errors. Can I just change the URL somewhere?
Here is the simplest reproducible command to produce a failure:
sudo apt-get ...
4
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1answer
76 views
Help installing add-on in GRASS, I get an error message
My Grass gives me this error message, Grass_info_error(4816,1):'make' required. Please install 'make' first. This happens when I attempt to fetch an add-on (r.viewshed). What am I doing wrong? and ...
4
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4answers
192 views
How to Find Dead-ends in a Road Network
I'm trying to remove all the dead-end roads in a road dataset (lines) that are less than 100m long.
How do I identify roads that are dead-ends (no exit)? The 100m part is easy. I know how to use Arc ...
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1answer
73 views
Set certain amount of pixels to 1 inside of a polygon (GRASS)
I have a rather coarse vector map with polygons and want to calculate a (sufficiently) finer raster map defined by spatial extension and resolution. Every polygon of the vector map has a value ...
9
votes
1answer
196 views
Is there a way to use ArcPy and PyGRASS tools in the same Python script?
I´m trying to write a Python script, that includes different ArcPy / ArcGIS commands and want to combine it with GRASS geoprocessing tools.
Unfortunately importing the GRASS libraries doesn´t work.
...
4
votes
1answer
148 views
Raster DEM generation
I have two shape files containing height information of a certain area and I need to create a raster DEM with GRASS using them.
file 1 consists of height information in contours (isolines)
file 2 ...
1
vote
1answer
136 views
Raster operation with grass.mapcalc
I need to iteratively add each raster map of viewshed analysis obtained from a series of single observer locations. For this i used grass.mapcalc with Python (GRASS 7 for Windows). However, my ...
2
votes
1answer
178 views
Integrated viewshed analysis
I need to do integrated viewshed analysis of a target with several observer locations. I am going to use r.viewshed analysis function in GRASS. With this function, it is possible to perform analysis ...
6
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1answer
271 views
How to enable GRASS-modules in QGIS?
I have the latest QuantumGIS-1.9.0-master from Github with python-modules support and full GRASS-integration (GRASS-4.6.3-RC2) on Linux.
When opening the GRASS-tools plugin, it only displays six ...
