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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705 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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938 views

Is it possible to use polygons to create heatmaps?

I hope I can explain my question clearly, so here it goes: I've been fiddling around with heatmaps on QGIS for a few days, but came across a small obstacle on my way. I have a dataset comprised of ...
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342 views

import parameters for r.watershed - (watershed basin analysis program) tool from grass using Qgis 2.2

I want to run this tool from Qgis 2.2 but i don't know how to use the PARAMETERS to run this tool. The red frame are the PARAMETERS I don't know. Can someone to tell me what those PARAMETERS are ...
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2answers
897 views

georeference and orthorectification of aerial photos

I am trying to process photos taken with a tetracam ADC micro camera placed on a UAV. I have GPS coordinates and mavlink logs providing roll, pitch and yaw of the UAV. I am having a real hard time ...
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362 views

Matlab script - how to access from/run in GRASS GIS?

I am currently working on shell script in GRASS GIS and Ubuntu. At some point, I must run a calculation (based on an ascii grid) that I have available as Matlab script and .exe (created from Matlab I ...
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365 views

Error “Unable to open data source” - import .shp into GRASS

I'm new to GRASS and GIS in general, so please forgive my ignorance... I have problem with loading Vector Data (.shp) into GRASS I used the following steps 1.1. and 1.2: http://qgis.org/en/docs/...
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32 views

nr of cells between cells

I want to do the following: I have a set of cells with the value 1, and a set of values with 2. I want to calculate for each cell [2] the distance - ideally number of cells - to the nearest cell 1. ...
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2answers
97 views

GRASS GIS using a loop with r.neighbors command

I'd like to do a trend analysis with ndvi data from 1982 til 2005. I am using the r.neighbors command to get first the spatial variance (then I would use r.series method=slope to get the actual trend) ...
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29 views

GRASS module r.fitpoly

I need to calculate the average daily temperature for each month. As an input I have 5 .asc grids for 6, 9, 12, 15, and 18 GMT for each month of the year. I was wondering if there is a predefined ...
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118 views

Extrude polygons with holes in GRASS using v.extrude

I have a shapefile with building footprint polygons. Many of the polygons have holes/inner rings within them (I'm not sure of the correct term in Grass). These import correctly into Grass GIS. I aim ...
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232 views

grass - add on problem

I can't install the addon in grass 6.4.3 to my linux mint. i've already installed the SVN and than it says: GRASS 6.4.3 (fabian_idrisi):~ > g.extension r.fuzzy Fetching from GRASS-Addons SVN (be ...
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90 views

Combining several rasters before r.surf.contour?

I have been trying to generate an elevation model from contour lines using first v.to.rast.attr and then r.surf.contour. Generally, it works pretty well, execpt for one issue. My data contains a lot ...
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91 views

Fill holes with an area bigger of a specific value in a raster coverage

I want to fill some areas of a raster coverage with a value of my choice. Those areas now contain NODATA values. So, they look like holes in my coverage. I know I could use r.clump function of GRASS, ...
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1answer
173 views

How to batch interpolate many shp´s to DEM

Here´s the problem: I have about 40 shapefiles of contourlines (type line) and I need to interpolate them to create DEM's (tiff, or better some grid format). To do so, some batch scripting would be ...
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1answer
84 views

How to reposition a polygon Shapefile using ground control points and v.rectify?

I'm new to Grass. I would like to reposition a polygon shapefile using ground control points and v.rectify seemed just the perfect tool to do that. The raster from which the shapefile comes from was ...
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1answer
33 views

Problems installing r.roughness

I am trying to install r.roughness in GRASS 6.4.3. It starts compiling but at the end I get this error: ERROR: Module did not install properly I cannot identify the problem. Can somebody that has ...
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1answer
437 views

GRASS 6.4.3 installed with QGIS not working

I'm new to QGIS and GRASS. I'm trying to do an image classification and it seems that the method I need is not within the GRASS toolbox in the QGIS . So I decided to use the standalone GRASS version ...
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1answer
570 views

Connecting Grass with R

I need help to connect R with Grass. In RStudio when I send the line: loc <- initGRASS("C:/Program Files/R/R-3.1.0/bin/i386", home=tempdir(), override=TRUE) It says: Error in system(paste("g....
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2answers
461 views

Select polygons that do not intersect any other polygon using QGIS, GRASS, SAGA or R

I would like to select the polygons of the layer below that do not intersect with any other polygon (within the same layer). How can I do this using QGIS, GRASS, SAGA or R?
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2answers
562 views

Create a common scale for different raster layers in GRASS, SAGA or QGIS

I have a number of layers that represent the temperature variability of the water in a lake. They have been generated trough interpolation and have different values as they represent temperatures ...
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2answers
80 views

How to remove small areas without reducing borders

I'm having a problem where I am overlaying two maps to create a new kind of map with the data conjoined. In general this is good, but I need to remove the smaller areas from it. For the interior ...
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64 views

Can QGIS alone can be used without installing grass?

can QGIS alone can be used without installing grass? i want to use functions of grass and i am not interested to create mapset and all. just with raster and vector files, i want to study temporal ...
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79 views

Producing gradients between shapefiles and using original boundarys as isoclines (lines)

to produce a bathmertical map of a river bed I draw shapefiles showing the different depths based on satellite images taken during different tidal levels (deepest, 2nd deepest, 3rd deepest, shore etc)....
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2answers
101 views

Adding time stamps to animation slides with OSS tools

I would like to create an animation with time lapse values printed on the PNG file. For this purpose I have created in QGIS a vector layer that stores timestamp and temperature value pairs for various ...
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1answer
114 views

How to mask the images in GRASS

I have MODIS NDVI images, which needs to be masked with VI_Quality. I am using GRASS software and executing GRASS commands using shell scripts. I need to perform raster calculation (multiplication) ...
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33 views

GRASS module g.mremove returns irrational outputs

I want to use g.mremove to remove multiple files in my mapset, import os import sys sys.path.append(os.path.join(os.environ['GISBASE'], 'etc', 'python')) import grass.script as g import grass.script....
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139 views

GRASS module g.copy returns irrational outputs

I took this as reference, Moving raster to different mapset GRASS GIS, and I use pyscripter to use GRASS module g.copy from outside, import os import sys #set up GRASS environment variables sys.path....
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1answer
25 views

vector file is used by two mapsets at a time in grass gis

i want to study about vector processing.if a vector file is used by two mapsets at a time, which one will be saved first and why.if a team want to work on the same set of shape files, what is the ...
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2answers
788 views

How to create a time series with a NetCDF raster from Ensembles E-OBS using GDAL, R, GRASS GIS or SAGA GIS

I downloaded a NetCDF file that contains daily precipitation values from 1-1-1950 to 30-6-2013. The raster has 23191 bands. http://eca.knmi.nl/download/ensembles/download.php My goal is to analyze ...
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2answers
134 views

How to number points along a line consecutively

I have a line and along this line I have different points which are max. 20m away from that line. Now I would like to number the points along the line, like shown in the grafic. Any suggestions how to ...
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610 views

Why my python script of r.watershed has no output?

I type those code in pyscripter, import os import sys #set up GRASS environment variables sys.path.append(os.path.join(os.environ['GISBASE'], 'etc', 'python')) import grass.script as g import grass....
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276 views

No data appears when using gdal_calc.py but source had data values

I'm in the process of calculating topographic exposure using a mix of GDAL, grass, R and python in Windows. I need to process a very large tiff file using the following calculation: arctan(topex_e.tif)...
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1answer
228 views

Better ways to check if GRASS r.water.outlet works out fine output

I use my python script to call GRASS module r.water.outlet from outside, and here's my script(I perform this script in pyscripter): import os import sys #set up GRASS environment variables sys.path....
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3answers
1k views

Convert 800 .hdf4 files to Tiff using GRASS/QGIS/SAGA/GDAL/R

I've have MODIS ndvi data (MODIS_Grid_16 days NDVI) from the iberian peninsula, from February of 2000 to August of 2012 (really big data). How do I batch convert about 800 .hdf MODIS files to .tif ? ...
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1answer
139 views

Difference between python IDLE and eclipse on accessing GRASS

I have seen these posts:GRASS and Python, Using Eclipse to develop GRASS Python programs. I used to use python IDLE to control GRASS, but I can't make python and GRASS connected, as I described in ...
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1answer
2k views

How to process MODIS ndvi data using QGIS/GRASS/R?

I have MODIS ndvi data (MODIS_Grid_16 days NDVI) from the iberian peninsula (3 tiles), from February of 2000 to August of 2012 (really big data). I want to know how to deal with this kind of files. My ...
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192 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 ...
2
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1answer
157 views

Matching two point clouds without loss (nearest neighbor, but more complicated)

I have two point clouds, one with demographic and one with electoral data. Points in both clouds represent the same empirical entity (say, a village, or an urban neighbourhood), but are not in the ...
2
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2answers
424 views

How to increase resolution of 3D image in GRASS NVIZ

I am trying to make 3D visualization of terrain data and orthophoto using GRASS NVIZ via QGIS. I have been able to import both the DTM and the orthophoto in NVIZ window and successfully draped the ...
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3answers
1k views

Problem with python script to control GRASS GIS from outside - How to import grass.script under Win 8.1?

I am working with GRASS 6.4.3 and python 2.7.6 under WIN 8.1. I am a novice with computer science and coding, and I have seen many posts including those:Is it possible to use GRASS GIS in Python ...
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1answer
83 views

RuntimeError from r.viewshed in graphic modeler

after using r.los in QGIS want to switch to r.viewshed in GRASS GIS 7. i need to do a lot of viewshed analysis form given points of a vectorlayer. if i try to add r.viewshed to the graphic modeler i ...
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1answer
111 views

QGIS-Processing GRASS-tools don't work

When I try to use the processing grass tools like r.series I always get the following messege. I deinstalled QGis and reinstalled the program totally fresh without success.
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1answer
250 views

Can one batch-automate the creation of QGIS heatmaps?

I have 4k point shapefiles, from which I would like to generate heatmap TIFFs using the QGIS heatmap plugin (or a functional equivalent featuring triweigth, radius and cell size selection). Is there ...
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2answers
417 views

How to do the loop when using GRASS module r.water.outlet?

I have seen this post:Watershed Analysis with GRASS, and I have a .txt file which contains coordinates of many points, and I want to use r.water.outlet to get basin area of each point. I type the ...
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0answers
986 views

QGIS cannot open output layers

I have problem with QGIS 2.0.1. Everytime I run tool from SAGA or GRASS, I get exactly the same error, for example: Oooops! The following output layers could not be open Channel Network: /tmp/...
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123 views

Grass 7 voronoi vertices error

I tried the voronoi diagram for area function and got the message "ERROR: Found 0 vertices" - any suggestion ?
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1answer
1k views

Snap points to line and calculate chainage using Open source GIS

I have a line layer (representing a pipeline) and a points layer (representing valves) and I would like to calculate the chainage of the valves along the pipeline. I assume that I would first need ...
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102 views

r.shaded.relief plugin on a DEM layer

I loaded a raster digital elevation map from the DEM explorer website. I defined the projection and created a mapset. I then loaded the raster file into GRASS with the r.in.gdal plugin to create a DEM ...
4
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2answers
417 views

95 percent volume contour

I generated, from point data, a kernel density map using GRASS, and I would like to identify the 95% volume contour in it. Is it possible in GRASS? Thank you
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133 views

Is there any GRASS command to measure the distance between a point in rastermap and another in vector map?

I have a question about WinGRASS 6.4.3. Is there any GRASS script command to measure the distance between a point in rastermap and another in vector map? I have a raster map and a vector map. Raster ...