DESCRIPTION

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

NOTES

A relative directory path (parameter directory) 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 output) results in the output file being placed in the "gdal/" subdirectory of the current mapset directory.

EXAMPLE

The module r.external.out can be used along with r.external to process external geodata in GRASS while writing out the results directly in GeoTIFF: 
# 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 > 20°C), write output directly as GeoTIFF:
r.mapcalc "warm.tif = if(modis_celsius > 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

SEE ALSO

r.in.gdal, r.out.gdal, r.external

REFERENCES

GDAL Pages: http://www.gdal.org/

AUTHOR

Glynn Clements

Last changed: $Date$