Difference between revisions of "GRASS 6 Tutorial/Raster data management"

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==Raster data management==
 
==Raster data management==
===Overview===
 
 
This section of the tutorial is intended to provide new users with an introduction to raster data management in GRASS GIS. As with other parts of the GRASS 6 tutorial, the examples are largely based on the GRASS 5.7 tutorial as well as the GRASS GIS presentation at Geostat-2012. The aim is to present the reader with introductory information on handling raster data within GRASS GIS.
 
 
 
===Data Import===
 
===Data Import===
 
In a similar way to the vector data management, the import and export of raster data is underpinned by GDAL. As such, the modules, <code>r.in.*</code> and <code>r.out.*</code> and specifically, <code>r.in.gdal</code> and <code>r.out.gdal</code> are used. The module <code>r.extenal</code> can be used in lieu of importing a raster into GRASS.
 
In a similar way to the vector data management, the import and export of raster data is underpinned by GDAL. As such, the modules, <code>r.in.*</code> and <code>r.out.*</code> and specifically, <code>r.in.gdal</code> and <code>r.out.gdal</code> are used. The module <code>r.extenal</code> can be used in lieu of importing a raster into GRASS.

Revision as of 02:18, 26 July 2013

Raster data management

Data Import

In a similar way to the vector data management, the import and export of raster data is underpinned by GDAL. As such, the modules, r.in.* and r.out.* and specifically, r.in.gdal and r.out.gdal are used. The module r.extenal can be used in lieu of importing a raster into GRASS.

A Geotiff can be imported into GRASS using the command line (input represents the full or relative path to the raster file you want to import; output is its raster name in GRASS). The same can be achieved using the GUI.

r.in.gdal input=elev_input_state500m.tif output=elev_input_state500m

Grass raster import.png


Sometimes, you need to define the region of the Mapset to the extent of your raster. For instance, using the above-mentioned example, you would simply:

g.region rast=elev_input_state500m

A common issue that users are faced with is how to import several GeoTiffs? Obviously the above steps can be repeated using the GUI or copy-pasting the command line or more simply using the following BASH for loop:

for file in `ls *.tif`
 do
  r.in.gdal input=$file output=${file%.tif}
done


Note - that when you run r.in.gdal, the full extent of the map is imported