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 set opacity for GRASS layers using command line?

In the process of learning GRASS, I am finding that I can learn many of the command-line methods that I need for scripting tasks from using the wxGUI, as it conveniently shows most of the underlying ...
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125 views

Error using “r.los” in QGIS

I am not a "computer person". So -- I don't know what this error message means. I found this question and answer for this same problem, but the solution did not work for me, dammit. GRASS algorithm ...
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3answers
265 views

Converting Landsat8 DN to TOA reflectance for use in envi

I am used to working in envi, however my current version does not support Landsat8. I downloaded GRASS for the express purpose of converting Landsat8 DN to TOA reflectance for use/analysis in envi. ...
2
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1answer
245 views

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

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 get it ...
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1answer
159 views

How to eliminate polygon boundaries

I'm working in both ArcMap and Grass I have a problem with the boundaries or the edges of my vectors. The vectors are a result of object segmentation (called classification) in Grass Gis. In Grass, ...
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2answers
54 views

Find coordinates of given raster value

I would like to get the coordinates of a raster cell with a given value. I suppose many cells can take the same value, in which case several coordinates should be returned. In my first problem I'm ...
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3answers
108 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 = ...
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35 views

GRASS scripting for producing multi-band raster

I am trying to loop the r.sun function within a Python script. Anyway, I seem not to understand how I can stack the raster maps each loop would produce into a single multi-band raster (preferably in ...
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36 views

TIF file creation from shapefile in GRASS?

Does anyone have any idea how to get around this problem? I've been looking for a solution to no avail. I'm trying to convert a shp file to a grid, and the tif is hanging up. Output raster layer: ...
4
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117 views

Convert downloaded LiDAR info to DEM in GRASS

I have downloaded LiDAR information as a .asc file and a .tif file, and even though I have tried multiple methods to convert them to a dem I am having no luck. Grass GIS says there is an invalid ...
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1answer
172 views

Combining Geological Grids and extruding between them?

I have a situation where I have 3 Geological grids, each showing a different horizon + the Seabed Grid. I need to extrude between these grids in order to make the 3D polygon for the geological ...
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173 views

Shortest distance from polygon centroids to a line in QGIS

To get the distance of each polygon centroid from a line, I have tried the Distance to nearest hub algorithm from the Processing Toolbox. The distances I got from the algorithm did not seem correct, ...
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230 views

How to specify column names with v.in.ascii

I have managed to import a CSV file into a points vector file using GRASS v.in.ascii v.in.ascii --o input=test1.csv output=test2 format=point fs=, skip=1 x=2 y=3 z=0 cat=0 This is test1.csv ... ...
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1answer
39 views

GRASS failed to import ESRI ASCII grid

I'm a new user of GRASS 6.4.3 and I wanted to import ESRI ASCII grid. Raster file was unzipped, and in r.in.arc window I specified name for output, storage type etc. After it has run, raster didn't ...
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1answer
53 views

Running GRASS functions in QGIS 2.4 from python console

I am using qgis 2.4 and i am looking for the "easiest" way to execute e.g. the r.in.gdal function from the python console in qgis. Specifically for r.in.gdal, I could not found this function in ...
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25 views

computing the volume of a cave

I did a cave survey and now I have a dxf file 3d. It's composed by 8 layers: polygonal points width contour width height contour height stations depth I would like to make a volume and change its ...
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5answers
3k views

How to calculate distances in a point sequence?

I'm looking for help calculating the distance between a sequence of points that are in a single Shapefile in QGIS. Below is what my data look like and a blank distance column I've added to show how ...
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1answer
31 views

Meaning of r.viewshed output numbers in QGIS?

I have completed a r.viewshed analysis of a point in GRASS7. I have imported the arising Geotiff into QGIS and when viewing the layer in the layer window (after expanding the +) I am presented with a ...
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2answers
41 views

Interpolate dxf polyline vertex elevation from DTM?

I am working on several autocad polylines (with several vertices...) that have the exact N,E coords but now I would like to add the elevation data for every polyline's vertices from a dtm. I thought ...
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2answers
42 views

convert DTM txt file in geoTiff file

I have a DTM file, txt format, I would like to convert it into GeoTIFF, how can I do with the software grass? thanks ncols 1329 nrows 1152 xllcorner 1693884 yllcorner 5080341 ...
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1answer
47 views

Manual (or examples) of r.ros, r.spreadpath and r.spread in GRASS

you can report me references or applications for use of the following modules (GRASS): - r.ros, - r.spreadpath, - r.spread. Thanks so much.
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8 views

bug in i.rgb.his

I found that the implementation of i.rgb.ihs in porcessing toolbox needs to be corrected. It is necessary to have admin permissions to correct the file i.rgb.his.txt locate in ...
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3k views

Visual Impact Assessment in QGIS or GRASS

Is it possible using QGIS or GRASS to perform a Zone of Visual Impact assessment? E.g. where can a 100m high structure be seen at a viewing height of 1.8m within 30km, taking into account elevation ...
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32 views

What Does the Cell Value in a Composite Raster Mean?

When I make a composite raster in QGIS using the GRASS r.composite tool and then click on a certain cell I get these values in the blue/green/red/composite rasters: blue = 124 green = 124 red = 172 ...
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47 views

v.generalize on massive vector data

I have a contour line file that covers the most part of north italy (shape is 0,6 gb) and I want to use v.generalize (snakes algorithm) on it. Because of the large file size, if I use Grass 6.4.3 I ...
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16 views

how to compile i.atcorr separately without compiling whole grass

i am working on grass. i need only i.atcorr module. should i compile whole grass 6.4.3 or any option is there for separate module compilation. I tried to compile entire gras6.4.3 on windows system but ...
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123 views

how to mosaic rasters in grass gis?

I am new user of GRASS GIS. I need to know how can i mosaic different satellite imageries using GRASS GUI? I was trying to use i.image.mosaic, but could not succeed. I have been looking for online ...
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21 views

r.univar - which format for working in GRASS GIS?

As part of a cut and fill-procedure,I want to run the command r.univar, but it returns with no output. I´ve been comparing the properties in the rasterlayer (rasterized vector-layer) with another well ...
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27 views

Change QGIS Processing (Sextante) default arguments for r.out.gdal

Lately I've been using r.grow through the QGIS Processing Toolbox on several rasters which represent the whole world with 500m grid spacing. It takes many minutes to save the output. The reason seems ...
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31 views

Importing raster and vector: GRASS GIS 6.4.4

Almost giving up on this task, and need some support. I´ve been studying GRASS GIS and training with some tutorials with The NC-dataset. What I want is doing the same task as the one called "Surface ...
2
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1answer
20 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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27 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 ...
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92 views

QGIS 2.4 NVIZ Solution

I am going to ask this question better: What happened with NVIZ? I do not know the exact version that nviz stopped working but it seems around version 2 of QGIS. There are two ways to get to nviz in ...
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4answers
167 views

Create a rectangular buffer from point shapefile using QGIS/GRASS/SAGA GIS/R

I have a points shapefile and I want to create a rectangular buffer (22 x 16 km) around each point. My goal is to create a 16x22 km grid where each of the points is the centroid of the grid. Seed the ...
2
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1answer
28 views

How to define measurement units in grass

I need to get the length and area of some landscape features in the US. My data was in lat and long degrees. I created a new location with an UTM projection and read the data into grass. Now if I ...
2
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1answer
64 views

Grass python shell can't find my data

I have a problem, the grass 7 python shell can't find my rasters. When I try to use the python shell to set the region I get "region not found". I can set the region in the grass shell (and other ...
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0answers
24 views

Error message retrieval in grass.read_command

I am writing a script in python and would like to get the error messages of the function grass.read_command for seeing why it is not working. I found a webpage ...
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2answers
53 views

Calculating quantile values over a stack of images with grass gis. Help needed on r.series

I need to calculate the values for the 25%, 50%, 75% and 90% quantile over a series of rasters (time series of ndvi values from landsat). I am exploring the r.series command in Grass GIS, but the ...
2
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1answer
19 views

Grass, Route Finding with Elevation Limits

I've got GRASS (7.0) installed and I "play" with it on ocassion since I am far from a GIS pro. What I want to do is to find all road routes from a certain point limited by distance (path length, not ...
6
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2answers
120 views

Remote geoprocessing solutions?

I have a relatively old laptop (i5 8Gb) but it is fine for most of my GIS needs. Infrequently I would like to run processes which requires larger amounts of RAM (16G+) but I cannot justify forking out ...
2
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1answer
52 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 ...
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2answers
62 views

Problem with Bash loop in GRASS GIS

I'm new to GRASS GIS and programming and I'm running into a lot of what I imagine are beginners problems and something similar to this has been asked before, but not In a way that I understand. I'm ...
3
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1answer
94 views

Practical tools to delineate large scale watershed?

I would like to do some watershed delineation at national/regional level (using SRTM-90 data). I have experimented with r.watershed (GRASS 6.4.3) but it fell over when I tried to do big stuff. I ...
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2answers
68 views

Tasseled Cap Transformation on MODIS in GRASS

I would like to know how to perform a Tasseled Cap Transformation on MODIS, in GRASS. I've found this https://searchcode.com/codesearch/view/19063909/ but I don't know if this has been tested. I'm ...
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1answer
46 views

How to use grass.script in MacOS

I have installed Python and Grass6.4 using Macports. When I tried to use "import grass.script" in python environment, it gives "no module found" error. I'd spend much time to fixed it but could not ...
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12 views

GRASS GIS 6.5SVN : r.watershed failed to display basin and accumulation maps

I am passing DEM and threshold values as inputs.I want to get basin and accumulation as outputs.I tried it in Grass,process was completed.while dispalying result it is showing white screen (both ...
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32 views

How can I load JSON into GRASS?

I have received rainfall data in JSON format. I want to load the data into GRASS. Sample JSON output: ...
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2answers
110 views

How to fix unreachable nodes in QGIS GRASS network?

I have created a network with the GRASS module v.net. But when I try to create the travelling salesman path with v.net.salesman, I get: Destination node 9383 is unreachable from node 9398 If I ...
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1answer
20 views

Cell file resolution differs from current region in GRASS GIS

Error r.terraflow elevation=cdnh43e_v1@user1 filled=cdnhfill direction=cdnhdir swatershed=cdnhsink accumulation=cdnhacc tci=cdnhtci ERROR: cell file cdnh43e_v1 resolution differs from current ...
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2answers
64 views

GRASS GIS: auto-completion fails in commande line

I'm running GRASS GIS 6.4.3. on Win 7, SP1, 64 bit. The path to my grass-DB is: D:\grassdb Within the GRASS GIS Commande Line, if I press the tab-key to auto-complete only folders, files and ...