Geografic-Information-System/raster/r.external.out/r.external.out.html

<h2>DESCRIPTION</h2>

<em>r.external.out</em> instructs GRASS to write raster maps as data
files (e.g. GeoTIFF) using GDAL.

<h2>NOTES</h2>

A relative directory path (parameter <em>directory</em>) is interpreted
relative to the current mapset directory, not the current directory where
the command was launched. An unspecified or empty directory (which will
occur if the user passes a simple filename for <em>output</em>) results
in the output file being placed in the "gdal/" subdirectory of the 
current mapset directory.


<h2>EXAMPLE</h2>

The module <em>r.external.out</em> can be used along with
<em>r.external</em> to process external geodata in GRASS
while writing out the results directly in GeoTIFF:

<div class="code"><pre>
# register GeoTIFF file in GRASS database:
r.external terra_lst1km20030314.LST_Day.tif out=modis_celsius

# define output directory for files resulting from GRASS calculation:
r.external.out $HOME/gisoutput/

# do something (here: extract pixels &gt; 20°C), write output directly as GeoTIFF:
r.mapcalc "warm.tif = if(modis_celsius &gt; 20, modis_celsius, null() )"

# cease GDAL output connection and turn back to write GRASS raster files:
r.external.out -r

# use the result elsewhere
qgis $HOME/gisoutput/warm.tif
</pre></div>

<h2>SEE ALSO</h2>
<em>
<a href="r.in.gdal.html">r.in.gdal</a>,
<a href="r.out.gdal.html">r.out.gdal</a>,
<a href="r.external.html">r.external</a>
</em>

<h2>REFERENCES</h2>

GDAL Pages: <a href="http://www.gdal.org">http://www.gdal.org/</a><br>

<h2>AUTHOR</h2>

Glynn Clements

<p><i>Last changed: $Date$</i>