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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0answers
9 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 ...
4
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1answer
73 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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0answers
3 views

grass gis i.atcorr input should be reflectance or radiance

my question is "what should be the input image in i.atcorr' for grass 6.4.4 version. i tried giving both reflectance(dn) and radiance as input but values are coming properly. i read some where, it ...
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0answers
12 views

Does r.sun require x11 to run? [on hold]

I’m writing a script to that calls r.sun, but I keep getting the error Unable to access the X Display, is $DISPLAY set properly? Can r.sun be called without an X11 environment being installed? ...
0
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1answer
19 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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20 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 ...
2
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0answers
12 views

QGIS GRASS shell commands not working in Yosemite

First time asking a question here. Running GRASS 2.4.3 within QGIS 2.4.0 on Mac OS 10.10 Yosemite. I'm trying to run v.net.iso within the GRASS shell, but the following error is returned every time: ...
0
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1answer
19 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 ...
2
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1answer
24 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 ...
0
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0answers
5 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 ...
2
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1answer
29 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.
2
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2answers
23 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 ...
3
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0answers
27 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 ...
0
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0answers
11 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 ...
1
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2answers
21 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 ...
0
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1answer
19 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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0answers
18 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
19 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 ...
2
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0answers
25 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 ...
2
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0answers
55 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 ...
1
vote
1answer
20 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 ...
2
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1answer
26 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
votes
1answer
46 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 ...
1
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0answers
21 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 ...
0
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2answers
44 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 ...
2
votes
1answer
18 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
votes
2answers
109 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
votes
1answer
32 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 ...
0
votes
0answers
9 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 ...
0
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1answer
26 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: ...
2
votes
1answer
81 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 ...
2
votes
1answer
32 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 ...
1
vote
2answers
45 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 ...
1
vote
2answers
37 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 ...
1
vote
1answer
16 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 ...
2
votes
2answers
75 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 ...
3
votes
2answers
52 views

GRASS GIS not starting

Hello my name is Luca and I write from Italy. I have a problem with GRASS GIS 6.4.3. Last week I installed QGIS 2.4 with GRASS GIS 6.4.3 GUI on Windows 7 64 bit - admin user. When I click on GRASS ...
1
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0answers
34 views

QGIS OD matrix assignment on network

Using QGIS, I would realize an assignment of an OD matrix on a network, like this one on Transcad. I have: - network - points of Origin and Destiny - flows of traffic for each OD I found a solution ...
1
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0answers
13 views

GRASS GIS and Liss4MX

i am working on grass gis. how to use grass gis for liss4 of IRS-P6.I have to do atmospheric correction for hilly terrain data.i would like to use grass's i.atcorr. may i know the dependencies and how ...
1
vote
2answers
60 views

How can I import tif file in GRASS GIS

While importing TIFF image to GRASS GIS, I get an error: Location PROJ_INFO is: name: Lambert Conformal Conic proj: lcc datum: nad83 a: 6378137.0 es: 0.006694380022900787 lat_1: 36.16666666666666 ...
0
votes
0answers
17 views

How can I implement GRASS GIS flow direction process from DOS scripting

When I try to implement its showing it work completely in its command prompt(grass) and creating output files also but when I try to view the result its not showing anything in Map Display I ...
1
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0answers
40 views

using r.volume model GRASS plugin in QGIS

I am calculating volume of bathymetric data in the form of a clipped raster in GRASS with a Custom Lambert projection centered around 70degrees North, using the module r.volume in GRASS. Side note: ...
0
votes
2answers
30 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 ...
2
votes
1answer
61 views

How to properly open an ASTER data?

Yesterday i downloaded an Aster L1B image from USGS's website. If i load it in QGIS, it doesn't get displayed properly(location wise). Even after i've enabled "On the fly" option, it's not reading the ...
2
votes
0answers
54 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 ...
0
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1answer
25 views

trying to calculate volume using r.volume GRASS - error message

I am trying to calculate volume using GRASS plugin in Qgis using module r.volume however the attached error message keeps appearing. Any ideas?
2
votes
1answer
35 views

How to convert tif to dep extension?

In white box when i try to import or do any processes it's asking .dep extension How can i convert .tif into .dep extension?? If try to pass LISS3 data in GRASS GIS it is taking as single bands. So i ...
6
votes
3answers
189 views

Cutting out depth information in raster. Calculating volume in Qgis

I am trying to calculate habitat volume for around 30 fish stocks in Qgis. I have habitat areas (shape files) and Bathymetric information (.tif file). I believe I can calculate the entire volume of ...
1
vote
1answer
39 views

Error importing raster into GRASS plugin in QGIS

I am trying to import a tiff raster file into GRASS however every time I do this the below error message comes up. I am using a custom CRS so I have tried changing it back to the default CRS but still ...
1
vote
1answer
32 views

Setting resolution for GRASS raster

I am trying to calculate volume using the GRASSplugin. I have my area information in vector format and my depth information in raster. I read that it is important to set the raster resolution before ...