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 get the elevation of the areas in a raster file from SRTM?

I have an SRTM elevation map. How do I get the elevation of each point in the map? I am using GRASS. Is there a GRASS script to do such?
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236 views

GRASS 6.5 or 7.0 - Need Help with Loop Script

I am new to Python and scripting in general. This is also my first time a posting question. My overall goal is to create a script that I can cycle through all the raster maps in a mapset and then ...
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2k views

How to reclassify a float raster?

I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
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624 views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
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121 views

Export Region definitions - GRASS GIS

I use two different Landsat datasets in different computers. But the region settings I work is the same. Is it possible to export the region settings in the form of a file in GRASS?
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381 views

Is it possible to use GRASS GIS in Python stand alone scripts?

I am trying to find a least cost path script for Python. I came across r.drain from GRASS GIS. Is it possible to use GRASS GIS in a Python stand alone script? If so where can I download the bindings?
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442 views

query raster cell values by point

I have a binary raster (0s and 1s) that I need to query given a set of point coordinates. This is easy enough to do with gdal (gdallocationinfo), but where it get's complicated is that I also need to ...
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How do I split polygons into line segments?

How can I split my polygon file into "segements"? The lines should be broken up like this picture shows:
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268 views

How to select a subset of separate bands in GRASS GIS?

As you know landsat data has separate files for different bands. Creating a subset is a wise option to work on region of our interest. Therefore, I used this method to subset my image - d.zoom || ...
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4k views

How do you Turn on the GRASS plugin in Quantum GIS?

I downloaded and installed Quantum GIS 1.5.0 with GRASS using the OSGeo4W installer on my Windows XP machine. Unfortunately, when I go to Plugins>Manage Plugins I cannot find the GRASS plugin. When ...
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118 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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243 views

How to do a looping to Interpolate a huge Rainfall Time-series in GRASS GIS or R

In GRASS GIS I have access to a table in PostgreSQL Database with this structure: Table Name: rainfall_time_series Columns: id | year | month | day | value_mm | x | y | gauge_code Setting g.region ...
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688 views

Altitude Above channel in GRASS 6.4

i'm fairly new to the GIS world and GRASS (come from econometric background), i would like to do some species distribution modeling using R and GRASS. So i started to read the book of Tomislav Hengl ...
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3k views

How to install add-ons in GRASS?

How do I install the r.inund.fluv script in GRASS? https://svn.osgeo.org/grass/grass-addons/grass6/raster/r.inund.fluv/
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327 views

How to know contents of column names in GRASS?

I am using GRASS to extract a specific area from a vector map. Here is the script that I am running: v.extract PHL_map out=makati where="AREA_NAME = 'Makati" The problem is, I don't know what are ...
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170 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 ...
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304 views

Merge two rasters with no data value

I have two rasters: Raster A and B. Raster A has has only values of 0. The white area in Raster B are No Data values. I want to merge them to one raster (Raster C). So basically I want all pixels in ...
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How to pansharpen LANDSAT 8 in GRASS?

Having used QGIS for quite some time for mapping, I was 'forced' to dig into GRASS as pansharpening is not directly executable in QGIS. After understanding more or less the structure, I did some ...
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5k views

Convert Shapefile to MySql

I have used Grass GIS imported a .shp file; I now want to export this file to MySQL. I understood that MySQL will contain the function of all three the files necessary in a Shape file system (.shp - ...
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565 views

How to enable GRASS plugin in QGIS 1.8.0 (Linux Mint 13 - 64 bit)?

Every time I enable GRASS plugin in QGIS (Plugins -> Manage Plugins -> GRASS), I got a message: Exception - G_getenv(): Variable GISDBASE not set. I googled and found some information here but don't ...
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597 views

Monthly Average Solar Maps (R.Sun) in Grass

I'm trying to create monthly average maps as described in R.Sun in Grass. I have my DSM. In reading the page on OSGEO it mentions that it is possible without showing how. Ideas? I assume I will need ...
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Where can I find a tutorial for installing an addon to GRASS GIS that a six-year-old could understand?

I want to use the r.stream.distance addon in GRASS GIS 6.4 on ubuntu 10.04 (64 bit). I've installed grass from the repositories and that works fine but I can't seem to figure out how to install this ...
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681 views

How to extract features from a vector layer?

I have a vector file containing the river lines of an area. I want to extract a specific water line from the vector. I used: v.db.select but it only displayed: ...
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79 views

How to choose a GRASS kernel density function?

I'm starting to use the Grass module on QGIS, and I want to do a heatmap, so, I'm creating a new surface using the kernel function. But, GRASS come with 7 types of kernel functions, how do I know ...
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311 views

R gridding and contouring options

I want to make an interactive web mapping application, which will grid and contour user data. My plan is to implement R scripts with Shiny, but the only R package I can find to do this is gstat. And ...
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How to generate a DEM from a contour Shapefile?

I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
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514 views

How to repair and clean contours from high data resolution (lidar)?

I'm unsuccessfully trying to make a bathymetric map with contours extracted from Lidar data at 1 m resolution. The extracted contours have a lot of artifacts like dangles and islands. First I used ...
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336 views

Topology problems with QGIS/GRASS

*edited file links below I'm working on several NGO projects at the moment, all of which are reliant on being able to use a district level map with some 490+ features, and I am running into some ...
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176 views

Programmatic raster-vector calculation

I currently use GRASS' r.mapcalc to find the difference between vector and raster data using a loop and temporary files and layers. Is it possible to do the core calculation between raster with a ...
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2k views

Importing shapefile in grass

I have very simple shapefile, which consists of couple of polygons, and I wanted to snap boundaries automatically. Unfortunately qgis doesn't have such function, but grass has according this answer: ...
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1answer
1k views

Quantum GIS Affine

I have a vector floorplan (DXF) that I've added to a blank project in QGIS using the Dxf2Shp plugin. I've been reading tutorials and StackExchange threads, but I can't seem to find out how to ...
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315 views

Multishading: bring them together to one Raster-Image

I made a multi-hillshade with 4 different light-directions and colors and stacked one above the other, each with its own transparency. Now I want to "save" the result in one raster-image. Whats the ...
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250 views

Autocorrelated DEM with QGIS or Grass

I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
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1answer
254 views

How can I avoid reprojection gaps when merging DEM rasters?

I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result: What do I need? Where could the ...
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1answer
181 views

Help installing add-on in GRASS, I get an error message

My Grass gives me this error message, Grass_info_error(4816,1):'make' required. Please install 'make' first. This happens when I attempt to fetch an add-on (r.viewshed). What am I doing wrong? and ...
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90 views

How are r.horizon results aligned?

I used r.horizon to calculate horizon on a raster every 10° without any offset. I have got 36 files now. Is the first file from 0° to 10° (then centered on azimuth=5°) or is it centered on 0°, in ...
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1answer
2k views

Convert shapefile lines to a polygon in GRASS

I have a shapefile of a map that is the outline of a number of islands. I would like to convert the lines into polygons (ie all islands filled in) using GRASS. I searched on how to do this with GRASS ...
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135 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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228 views

How to create a topologically correct dataset in PostGIS (with GRASS)?

I have shapefiles which I have loaded in postgis and now i am trying to use geometric function in postgis like ST_intersect and they fail because the data is not topological correct. I have tried to ...
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153 views

What open source solution would work best for auto extracting features from satellite images? [duplicate]

Possible Duplicate: Feature Extraction - Land cover I have been looking for an open source solution which would allow me to define a region (or collection of images) and extract features ...
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2answers
361 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 ...
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2answers
1k views

1'' DHM: Hillshade is too rough - how to “generalize”?

I got this hillshade from my DHM (I used the hillshade-module from qgis). For my purpose there is too much relief detail (roughness). How can I get rid of this in QGIS or GRASS? Thanks! Martin
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186 views

Is there a shortcut in GRASS for importing vector files?

Is there a keyboard or command shortcut in GRASS for importing vector files? If you know link where I can find maybe whole list of shortcuts for GRASS, that would be awesome. Thank you.
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578 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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974 views

How to set all pixels with value <= 0 to “nodata” in DEM raster?

I have a DEM raster with pixel values between about 3000 and -0.0003. I need to set all pixel with a value of 0 and smaler (<=0) to "nodata" (for later raster calculations and to reduce the ...
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1answer
2k views

How do I find vector line bearing in QGIS or GRASS?

How can one extract the bearings from a set of lines in a vector file? I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
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431 views

Can a raster map in GRASS be saved in JPEG/BMP format?

I'm trying to save a raster map in GRASS in jpeg/bmp format without using the GUI for d.out.file/d.save. Is there a script to do it? I tried r.out.gdal but it produced a map that is black and white.
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205 views

SVN Version of GRASS and QGIS

I have GRASS6.5 SVN installed and wanted to go for SVN installation of Quantum GIS in Ubuntu 11.04. So as instructed in QGIS Wiki, I added the qgis repository to my sources.list file. Now I am able to ...
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338 views

Creating square buffer in qgis

How can I create a buffer with square ends along a line segment in qgis? I've buffered lines using v.buffer in the GRASS plugin, but the -c option for square ends is not exposed in that interface. ...
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187 views

Create network from shapefile without ArcGIS?

I want to perform shortest-path analysis on a network whose edges represent real-world roads and whose nodes are buildings or other locations. I have the shapefile for the area I'm interested in. ...