[GRASS-user] Re: Import question

Hamish hamish_b at yahoo.com
Tue Sep 21 02:25:16 EDT 2010

Adam wrote:
> I ended up just using r.composite on the maps that I had
> imported.  That did the crop to the current region that
> I had expected.  Then I deleted the 45 gig of maps that
> I didn't need, but already had.  
> The gdal_translate looks like a great solution for next
> time, before I do the huge import.

to sum up:

* r.in.gdal differs from most raster modules in that it imports
the entire map and ignores the current region.

* gdal_translate can be used to crop out an area of interest
before import with its -projwin or -srcwin options.

* after import any subsequent raster module will respect the
region settings, so in effect crop to the current region. The
most basic example of this is: "r.mapcalc "cropped = imported".

* r.composite is lossy, which is important for analytical tasks
but not for visual use. If analyzing the data keep it in
individual R,G,B bands.



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