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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21 views

Error using Grass v.clean

I am trying to clean topology of a TAB file in QGIS 2.14.4 and it returns an error message as below The weird thing is, I am able to execute this okay on my machine but not my colleague's. The other ...
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37 views

QGIS GRASS: Error when converting vector to raster

I am trying to convert a vectorial layer (a grid of regular points with values, representing probabilities, associated to each point). I tried to use QGIS, but I got this error: ERROR 1: Attempt to ...
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26 views

Comparison of % change in two photos with GRASS

I have two aerial photos of the same location taken at two different dates. Is there a way to compare the % difference between those two images using GRASS or is there a better tool? Sorry, also if ...
2
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26 views

Downloadable pdf format of GRASSGIS 7.0 manual [closed]

Can anyone help with a link or something that could enable the download of a pdf version of the grassgis manual? I am having a hard time trying to convert the html version into printable pdf. Nkeze
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28 views

How do I merge a point attribute table to a polygon attribute table in QGIS or GRASS?

I have a point layer containing the following data: I want the following polygon areas to be added to the point attribute table as all the points occur inside the various features of the polygon ...
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100 views

Grass processing not configured in OSGEO4w QGIS 2.14.1

I get the below error when I try to use grass processing from within QGIS. The error is given on all commands and I have got this error on 2 machines. I am using windows. "This algorithm cannot ...
2
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1answer
38 views

QGIS graphical modeler: how to automatically enter parameters in r.drain.coordinate tool

i am carrying out a cost least path analysis and i am using QGIS. The processing tools i am using are: r.cost.full and then r.drain.coordinate Considering i have more than 1000 layer to process (...
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28 views

Attribute table update after v.split on GRASS GIS [duplicate]

So I just used v.split to create shorter segments (with just 2 vertices) of my contour lines. I was left with about 22000 lines but, when I open the attributes table, I find no more than 45 entry ...
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52 views

Avoiding edges using GRASS generalization?

I'm trying to process the national wide land cover data into vector polygons. In order to be quick I separate the data into several tiles and process them in parallel. process flow is : 1. v.in.ogr ...
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38 views

C/C++ function to return minimum set of points required to represent a geometric shape

I am looking for a method from Grass, GEOS, or similar that will delete those points in a geometry which do not affect its shape. Example 1 +----+----+ p0 p1 p2 p1 can be deleted without ...
2
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40 views

Matching raster regional extent with vector region in GRASS?

In Grass GIS, I am able to import bathymetry .tif raster data however the region coordinates are not in lat/lon formar and therefore, do not overlay with my vector points which are in lat/lon format. ...
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40 views

QGIS - WHERE SQL within a processing.runalg statement for v.surf.rst in python console

I'm creating lots of raster files with grass:v.surf.rst so rather than using the graphical interface I wanted to use the python console (and potentially put in in a script at some point). However ...
2
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1answer
136 views

Atmospheric Correction Model Output for Landsat 8 Image?

Following are my procedure, observation and question/ request: Data Source: Earth Explorer Landsat 8 Grass GIS Version: 7.0.2 RC1 Windows 7 32 bit OS I have been trying to conduct an Atmospheric ...
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34 views

v.clean batch process withing QGIS 2.10 (PISA)

I get an error message when i try to creat a batch for v.clean operation.. Algorithm v.clean - Toolset for cleaning topology of vector map. starting... local variable 'filename' referenced before ...
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162 views

Module nziv not found in QGIS 2.10.1-Pisa

I want to use nviz in QGIS2.10.1-Pisa on windows 7 and I always get the same warning message : "Module nviz not found", whenever I click on it in the GRASS tools Modules list. I have tried to ...
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56 views

“Identity” equivalent in Grass GIS

In ArcGIS and SAGA GIS there is the "identity" tool, which creates a vector overlay and shows area contributions of polygons in shapefile B to the polygons in shapefile A (in the attribute table). ...
2
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1answer
345 views

Using Spyder IDE to develop python for Grass GIS, get 'ImportError: No module named grass.script'

I am trying to use Spyder IDE to develop a python script using python library from grass-6.4.3. I run the script below, and get 'ImportError: No module named grass.script' I am using python 2.7, ...
2
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1answer
115 views

GRASS: Landsat 8 GeoTIFF import error

I'm trying to import some Landsat 8 GeoTIFFs into GRASS (in QGIS), and I can't work out why I'm getting this error, or how to fix it. No amount of Googling has been able to tell me anything at all. I ...
2
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1answer
231 views

How to use GRASS v.kernel to calculate point densities along a network?

In a road network, I need to select the segments where a minimum of 5 dots occur (1 dot = 1 address) over a distance of 100 m (the image attached illustrates my question). I'm trying to use GRASS v....
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125 views

how to orthogonalize building outlines

I'm looking for a way to orthogonalize building outlines which I've extracted from a high-res DEM. I'm using the FOSS GIS stack (QGIS, GRASS, SAGA, PostgrSQL, PostGIS) and can code in Python (or Java)....
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143 views

Least cost path analysis : a lot of sources and destinations

I'm working on a 15*10 km area, splatted in a 50*50 m cell grid. I want to compute the time needed to travel from a single starting point to each cell centroid, combining driving and walking time. I ...
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68 views

Calculate cover loss between years using r.mapcalc

I am working on forest cover raster data for 2 years and am interested in areas with >5% loss in forest cover. I am pretty new in GRASS GIS, so any suggestions for how to create a difference map of ...
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66 views

Sophisticated generation and calculation of Vector entities from Raster Data?

The first image below is shown a raster wish represents the altitude value. I created this raster by applying this process, bu using this process we can manually select an upper and lower area (so 2 ...
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141 views

How to use d.* from a python/bash script in GRASS GIS 7.0?

Do d.* commands from GRASS GIS 7.0 run from a python script? I'm trying with this code: import grass.script as grass grass.run_command('d.mon', start="wx3", resolution = '1') grass.run_command('d....
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37 views

Error using grass script v.lidar.edgedetection

I'm in trouble with the grass script v.lidar.edgedetection. When I try to filter an xyz format dsm the script starts but at the end of it an error message appears (see attached image). Somebody ...
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139 views

How to build a GRASS network with node IDs from the line dataset?

I have a dataset of street network links (line geometries). Each network link has a link id, start node id, and end node id attribute. I want to use this network in GRASS, so after importing the lines,...
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94 views

3d model to point cloud

Excepting FME, is there a way to convert 3d model to point cloud?
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158 views

QGIS-GRASS firespread simulation module [closed]

I'm trying to do some fire spread simulations in QGIS with GRASS fire spreading simulation module. QGIS ('Processing Toolbox' > 'Geoalgorithms' > 'Misc' > 'Fire spreading simulation') GUI. Already ...
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596 views

QGIS 2.8 problem accessing GRASS commands [duplicate]

QGIS 2.8.1 Win7 64 bit installed with osgeo4w-setup. I’m trying to run GRASS commands on a LIDAR raster layer but I get the following message: Missing dependency.... GRASS not installed in your ...
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289 views

Import vtk file in grass gis

last summer I made the relief of a cave, and at this time I returned with Therion software. This survey is in 3d and I can save it in the formats .Lox, .3d, vtk. I would like to import it in grass or ...
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110 views

GRASS 6.4.4 vector command in crashes QGIS 2.4 (g.gisenv.exe has stopped working)

I am running Windows 8.1 64 bit, and have QGIS 2.4 and 2.6 installed. When I try to use a GRASS 6.4.4 vector command (specifically v.clean), I receive an error message in an endless loop, and the only ...
2
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1answer
54 views

Appending map to another map using GRASS?

I'm trying to simply append a map to other map, without any sort of geometric operations as merge or intersects, just the original geometries with theirs attributes. This is what I already tried: # ...
2
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2answers
33 views

Harvesting pixels using GRASS GIS

having a binary raster map of pixels of interest, a road network, and a target point, my goal is to get a raster map with network pixels having as value the number of pixels of interest they allow to ...
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35 views

infer the altitude from a DTM & finally provide it to point / evincere la altitudine da un DTM & finalmente fornirla a dei punti

I would like to complete a point vector's table with Z data. I am not able to take Z coordinate from a dtm (downloaded from http://www.regione.piemonte.it/geoscaweb/index.php?pgs2=0&pgs3=DTM10&...
2
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1answer
313 views

r.recode rules file issue

I have a raster that I want to reclassify and I'm using GRASS r.recode from within QGIS v.2.4.0. The rules file I am using has this content: 0:149:1 150:229:2 230:379:3 380:459:4 460:*:5 The raster ...
2
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0answers
758 views

How to merge overlapping and duplicate lines from vector layer to one single line?

I used the "polygone to line" tool from QGis, to get a line-layer from this polygon-layer: unfortunatly this causes overlapping and duplicate lines, after I broke the qgis-export via GRASS into ...
2
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0answers
217 views

best method for gridding or interpolating elevation data

I wonder if someone can recommend the best method for gridding elevation data in QGIS, GRASS or similar. The elevation data I have is collected along 1m spaced lines at approximately 1 reading per ...
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259 views

3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS

How can I make 3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS? I am quite new with GRASS. I have only managed to get a 3D view of the terrain so far.
2
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0answers
180 views

QGIS doesn't recognize GRASS commands

When I try to use GRASS commands in QGIS, I get the following error message: Missing dependency.This algorithm cannot be run :-( This algorithm requires GRASS to be run. Unfortunately, it seems ...
2
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0answers
46 views

Can't run SAGA or GRASS commands from QGIS processing toolbox [duplicate]

I can't run anything from this toolbox. I tried running SAGA dissolve polygons and got the following error : Oooops! The following output layers could not be open Dissolved Polygons: C:\Users\Amine\...
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413 views

Problem loading output layer QGIS

Every time I run operations with temporary file output from the graphical modeler, I get the following error message: Oooops! The following output layers could not be open CLIP: C:\Users\Amine\...
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0answers
81 views

Background (sky/terrain) of a viewshed

Is it possible to determine whether a point feature of a particular height would be backed by sky or by terrain? I've done the viewsheed analysis of a wind turbine. Now I would like to make a raster ...
2
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0answers
136 views

QGIS V. parallel command using GRASS

I cannot offset a line to a specific decimal place, (ie only whole numbers can be inputted) Am I missing something here??
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0answers
87 views

Longest slope oriented to north?

I need a help with my homework. I have created digital elevation model from the shapefile. In QGis(Grass plugin) This is how far i can go. I have to find the longest slope oriented to North. I know ...
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248 views

how to make decent sense from scattered river depth measurements

I sampled river depth at scattered positions and I want to be able to make a map and GIS layers out of it. My problems are: As the river meanders the interpolation I do in scientific packages i,e. ...
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296 views

How can I create random concave polygons for test purposes?

In the context of generating random test data using QGIS (in a shapefile): I can generate random, continuous (adjacent) polygons by first creating n random points using ftools and then generating a ...
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244 views

How to Install GRASS Addons to use in QGIS [duplicate]

WIN 7 QGIS 1.8.0 GRASS 6.3.4 I want to use r.viewshed in QGIS. therefore i want to install it in GRASS by using the GRASS interface. Followin Error appears. g.extension.py extension=r.viewshed ...
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609 views

How to specify cost attributes for network analysis in QGIS using the GRASS plugin?

I have a road dataset with information about the length, speed and drivetime for each segment. I use QGIS 1.9 with the GRASS plugin to do different types of network analysis, but how do I set up the ...
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2k views

How do I change from lat/long to a metric coordinate system in GRASS?

Yes, it's yet another transformation question. I am working with ASTER DEM data, which is LatLong WGS84. I want to process the DEM map into an STL file for use in a CFD simulation. The script I am ...
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265 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 ...