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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3
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2answers
759 views

minimum distance from the shore (how to retrieve the “shore vertices”)

I am student of Statistics, this is my first time using GIS., I am sorry for the stupidity of the question but I browsed online and could not find a satisfactory answer. I have some spatial data in ...
1
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1answer
67 views

How to fix this “Sorry <1> is not a valid option” in GRASS-Ubuntu using r.water.outlet?

I am working with this .sh code (a while loop, extracted from: http://www.surfaces.co.il/) to create watersheds from drainage raster and outlet point of every watershed, but I obtain this error: ...
2
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1answer
1k views

What am I doing wrong with QGIS v.clean?

I thought I understood how the GRASS v.clean tool worked in QGIS (in 2.6.1 Brighton) but I keep getting unexpected results and errors with a polygon ShapeFile. I've run the QGIS TopologyChecker with ...
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0answers
186 views

Defining the boundary of a catchment area

I digitized contour lines from topographic maps and created a DEM. With the DEM, I estimated the boundary of a catchment area. Estimated positional accuracy of topographic maps is RMSE = 65 m, with a ...
1
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1answer
401 views

GRASS 7 - raster calculator “and”

I am struggling with one thing in the raster calculator in GRASS GIS 7: I want to create a raster_b from raster_a, with raster_a values between >=-0.15 and <=0.15. The raster containing values ...
3
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3answers
795 views

How to calculate peaks in a DEM

How could I extract all peaks from a DEM (large mountainous area)? Peak means something like: a pixel which is sourrounded by other pixels with smaler elevation numbers in a area arround the ...
1
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1answer
206 views

Which DOS method use to convert at-sensor radiance to at-surface values in GRASS (landsat data, i.landsat.toar modul)?

I am trying to calculate surface reflectance values from raw Landsat DN data downloaded from GLOVIS. I have imported Landsat data in GRASS 6 with header by i.landsat.import and reprojected the scene ...
2
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1answer
51 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: # ...
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0answers
113 views

GRASS GIS G_malloc error

I am new to GIS. I downloaded GRASS and the sample data sets and am attempting to use the tutorial at: http://grasswiki.osgeo.org/wiki/Quick_wxGUI_tutorial. During the step, "Create a random ...
0
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0answers
32 views

Changing tracks to vectors in a grid

This is a version of a question that I posted on the GRASS list, but I didn't get any suggestions there. I would like to overlay a grid (cell size about 500 m x 500m) over an animal track created from ...
1
vote
1answer
404 views

How to debug “Unable to load GDAL library” error in QGIS 2.0?

I have a problem with r.surf.contour. I create a DTM with v.to.rast.attribute and then use the r.surf.contour and it works fine in QGIS 1.9 but with QGIS 2.0 doesn't work. I have a contour shapefile ...
2
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0answers
99 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 ...
0
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1answer
120 views

GRASS GIS v.in.ply

I'm trying to import a .ply file from MeshLab 1.33 into GRASS GIS 7.0 using v.in.ply addon, but I get the error message: ERROR: List index must be integer, is uchar This appears to be referring to ...
1
vote
1answer
39 views

Cost Surface No sense Results. GRASS

I have some doubts with the generation of a cost surface with r.walk of GRASS. It's assumed that the resulting layer is measured in seconds, but when I try to convert seconds in days march (6h per ...
1
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0answers
28 views

Distance between each feature from and every feature to in GRASS

In GRASS, v.distance calculate the minimum distance from each point feature in the 'from'-layer to the nearest feature in the 'to'-layer. I should instead calculate the minimum distance from each ...
1
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1answer
93 views

Grass GIS “v.in.ogr”: How to prevent crossing lines from beeing split where they don't share a common node?

I want to import a road network into grass gis to run network analyses. I use "v.in.ogr" to import my road shapefile. The problem is that Grass GIS seems to split every crossing line no matter if they ...
5
votes
2answers
2k views

Is there a Focal Statistics (spatial analyst) tool in ArcGIS equivalent in QGIS?

I'm attempting to use QGIS v2.0.1 to accomplish the same tasks that I can do using ArcMap v10.1 and I'm running into some trouble finding equivalent tools. In ArcMap I am using the Focal Statistics ...
4
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2answers
681 views

How to determine aerosol model value for i.atcorr in GRASS?

The i.atcorr module in GRASS requires aerosol model data to perform atmospheric correction using the 6S algorithm. It seems like I need a value from one of these parameters to continue: Estimate ...
0
votes
1answer
161 views

Qgis map composer shows a huge red cross

I can show this best by a picture: This cross also shows when I export it as raster or pdf. What is it and how can I get rid of it? I am using Qgis 2.4 and the map was done with the help of the ...
1
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1answer
139 views

Adding items to DEM in QGIS

Working with QGIS and Grass I would like to produce a ZTV. I have the bare land DEM happily ready to go but would like to add buildings and woodland to the calculation. Can anyone please point me in ...
0
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1answer
80 views

Problem installing r.hydrodem with g.extension in GRASS 7.0.0svn (r61585M) on mac OSX 10.10.1

I'm very interested in using the function r.hydrodem in GRASS, unfortunately, I'm running into some problems when trying to install this add-on in GRASS 7. I've tried installing some other add-ons ...
11
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1answer
518 views

SEXTANTE toolbox - GRASS error

I am trying to use the SEXTANTE module GRASS (and SAGA) for vector analysis but whatever function I use I always get the same error:"Could not load layer: G:/closest.shp Check the SEXTANTE log to look ...
1
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1answer
66 views

Intermittent multi-threading in Grass 7?

I have a script with runs GRASS 7 r.li.* commands through R with spgrass6 on Ubuntu 14.04/64 bits. I ran the script and was amazed at the speed at which it was running. So, I looked at the system ...
6
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1answer
206 views

Cell declustering using open-source software

I want to perform cell declustering in a small point data set. I have 9 observation points and I want to find the size of the region of influence for an observation, and afterwards use that as ...
8
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4answers
3k views

How to find dead-ends in road network using ArcGIS for Desktop or GRASS?

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 ...
1
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1answer
75 views

Compute nearest points to other points using GRASS

I have a layer of address points and a layer of polling stations. My task is to determine the three closest polling stations to each address on the street network. I think that the answer is in ...
15
votes
2answers
3k views

Is there a way to automate the preprocessing of LANDSAT data?

I'm currently enrolled in a remotesensing course, using LANDSAT data. Part of my course is about standardizing the scenes based on radiance values. I assume that because this is such a tedious task, ...
2
votes
1answer
52 views

can grass modules work separately

Grass is very useful tool for pre processing of imagery. I want to use the i.atcorr module separately. Will it be possible? I have compiled using .cpp files (AerosolConcentration.cpp, ...
1
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1answer
117 views

Only run r.neighbors if cell meets criteria

This is my first time using GRASS to work with Rasters, so please excuse my lack of knowledge on the subject. I want to run the GRASS r.neighbors function on cells that meet a specific criteria, ...
2
votes
2answers
307 views

Looking for guidance to create a hydrological map with QGIS and/or GRASS

I have QGIS and GRASS installed . Basically i need this program for making maps something like this: https://www.youtube.com/watch?v=5HuPX7JS7ZA I downloaded DEM from ...
9
votes
5answers
6k views

How to workaround large mosaic process which is failing?

I need to mosaic about 550Gb of tif imagery together and the software I have tried keeps failing. The area has been split into zones so that the smallest has approx 200 tiles. I have used the latest ...
1
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1answer
47 views

How to add grass64 to PATH variable

I recently installed GRASS 6.4 in a Unix environment. The application opens fine, but I would like to also be able to run the GUI from the command line. The tutorials says that the grass64 command ...
3
votes
1answer
121 views

To make a map of sinkholes on grass gis

I would like to make a map of sinkholes. I have a DTM ARC/INFO ASCII GRID of Asiago Plateau and and I'm using grass gis. Does anyone know what is the correct form in grass gis?
0
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2answers
62 views

changing mapset in cmd

can anyone suggest me for changing mapset from current location using command prompt.I have compiled the grass gis 6.4.4 and when ever i want to use the commands every time i am opening gui and ...
2
votes
1answer
331 views

Fuzzy maps with QGIS/GRASSGIS

How to do fuzzy maps (FUZZY module in IDRISI) with QGIS/GRASSGIS?
4
votes
1answer
621 views

How to reproduce Smoothing from Generalizer Plugin in v.generalizer in Processing Toolbar using QGIS?

I´d like to reproduce the smoothing operations done with the Generalizer Plugin inside the v.generalizer Toolbox so I can use them on a polygon layer instead of only on a line layer. I tried ...
1
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0answers
50 views

GRASS GIS 7, Windows 8.1, Graphical Modeler, Export to Python

I need help. I´m trying to export my model made in Graphical Modeler in Grass GIS 7.0.0 beta3 to Python Script. The exported file contains only header.
1
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1answer
195 views

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 ...
0
votes
1answer
235 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 ...
2
votes
1answer
434 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 ...
1
vote
1answer
209 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, ...
4
votes
3answers
124 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 = ...
1
vote
1answer
193 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 ...
0
votes
0answers
41 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
votes
1answer
246 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 ...
3
votes
1answer
302 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 ...
3
votes
1answer
556 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, ...
0
votes
2answers
294 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 ... ...
0
votes
1answer
141 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 ...
0
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0answers
43 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 ...