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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1answer
41 views

Problems running grass.mapcalc

I am using the GRASS Python Scripting Library on Ubuntu 14.04 with the packages available from the Universe repository. I have the following block of code: try: ...
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2answers
96 views

Convert a mask image to polygon shape file using GRASS

I used image classification technique in GRASS GIS v7 and generated the image mask below in which white area has NULL value and red area contains 1. I am going to clip those red color areas in a ...
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0answers
66 views

Running a batch script in GRASS command line - v.dissolve and v.db problems

I have been writing a number of scripts for automating isochrone production in GRASS just using the command line. I create files with isochrone lines in them and then a buffer around each of the ...
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1answer
23 views

r.series command in QGIS - timeseries

I am using r.series command in qgis. The command is performing correctly, but when I import input raster files, it creates a list in a random order. Sometimes the order of input rasters is essential ...
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0answers
77 views

QGIS r.cost / r.drain and errors

I'm trying to find the optimal route of several archaeological sites with Qgis 2.2. I've a DEM and r.walk or r.viewshed executed successfully, but r.cost always fails creating the output, however ...
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42 views

time processing

I am computing NDVI for Landsat TM in grass 6.4.3 in raster map calculator, and time processing is many hours and finally tke message is "failed". trying to find a solution I discovered that it ...
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1answer
84 views

r.viewshed - Can't find with Grass toolbox

I'm trying to use r.viewshed and have got Grass installed but can't find it anywhere! under toolbox, I click 'Grass commands (152 geoalgorithms) and have a choice of imagery, raster, vector, etc, ...
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22 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 ...
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31 views

R equivalent of GRASS r.grow?

What is a good R equivalent of the GRASS function r.grow? The closest I've been able to find is the script suggested by whuber in response to Creating randomly shaped clumps of cells in a raster from ...
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0answers
45 views

v.buffer angular buffer doesn't take all the polygons into account

I am trying to create an angular buffer around building footprints with the v.buffer command (QGIS 2.2). There is no error message, but the algorithm doesn't take into account all the buildings. This ...
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1answer
66 views

List the projection & datum of all the files in a folder

In QGIS/GRASS, is it possible to list the projection details of all the shp,tab,dxf files in a folder ? We are having 100 - 150 files in too many folders. We would like to create a table of Proj ...
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21 views

Is it possible to compile a grass addon into a commandline app?

As the title says, I'm wondering if it's possible to take the source of a grass add-on and compile it into a commandline app. Or, alternatively, use the add-on in a python program. Basically, I ...
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54 views

How to make DTM Qgis-grass

Good evening, I need help. Should I create a dtm of an area in the province of Vicenza. It 's the first time I try, I tried the tutorials on the Internet but I could not understand how to do it. Could ...
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0answers
165 views

GRASS “Argument list too long” with run_command

I have a python script that uses the grass.script.run_command function to read in, process, and export a bunch of raster files. On projects where I have a large number of rasters (>1,000), it fails ...
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1answer
109 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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1answer
106 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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1answer
111 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 ...
2
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1answer
146 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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2answers
155 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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0answers
86 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: ...
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0answers
24 views

External scripting in GRASS libgrass_grass.6.43.dll not found

I need to run interpolation through GRASS through a script such that its requires no user interaction in the process and the interpolation raster output can be used for display in HTML Web Page. To ...
1
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1answer
26 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
56 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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1answer
17 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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0answers
44 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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0answers
45 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 ...
1
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1answer
44 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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0answers
30 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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0answers
35 views

Delineating catchments using GRASS GIS?

I am trying to delineate catchment using GRASS. Can anybody point me to "easy to understand" type of notes for GRASS? Will appreciate any help.
1
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1answer
67 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
47 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 ...
0
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1answer
17 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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0answers
57 views

QGIS 2.2 freezes when I select a Grass command via Processing toolbox

I'm on Ubuntu 13.10, and I have never been able to get the Grass plugin to work in QGIS 2.2 via the Processing toolbox. As soon as I select any Grass command, QGIS locks up, no menu appears. I then ...
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1answer
97 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 ...
1
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1answer
127 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 ...
3
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2answers
156 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
126 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
53 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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1answer
56 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 ...
0
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1answer
53 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 ...
1
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2answers
33 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 ...
1
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1answer
47 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) ...
0
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1answer
26 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 ...
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1answer
74 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 ...
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0answers
112 views

GRASS module g.mapset can't create new mapsets from outside

I use pyscripter to control GRASS from outside. I want to create a new mapset named water. Here's my script to generate new mapset, import os import sys #set up GRASS environment variables ...
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1answer
22 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
212 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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0answers
12 views

Printing a label from a point layer attribute on a raster layer (GRASS)

I am interpolating with boundaries using v.surf.idc in GRASS. It works wonderfully and I fully recommend it. I am creating an animation and I use v.surf.idc to generate sequential interpolated raster ...
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2answers
94 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 ...
1
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2answers
262 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 ...