[GRASS-user] Advice needed - quickest way to create a mosaic

geep999 geep999 at yahoo.co.uk
Sun Mar 14 05:45:56 EDT 2010

I need some advice on the quickest way to create a mosaic.
I have sucessfully used the example from the r.patch manual page:
MAPS=`g.mlist type=rast sep=, pat="map_*"`
g.region rast=$MAPS
r.patch in=$MAPS out=mosaic
I have 115 1 degree ASTER tiles that I want to mosaic together before
re-projecting with r.proj.

My 1st attempt was to run r.patch with a list of all 115 tiles.
It didn't seem to progress - the progress stuck at 0% for about 5 minutes. I
killed the process.

My 2nd attempt was to create strips for each degree of latitude and then
patch the strips together.
There are about 10 tiles in each strip. Each strip took a few minutes.
Patching the 14 strips together took more than 1 hour (2.3GHz Intel Dual
Core + 4Gb RAM).

Should I have waited for my 1st attempt to finish?
Or is it more efficient to create strips, and then patch the strips

Is there another faster method?
I have tried using gdalwarp, but with large areas it eats up all my RAM,
starts swapping and 
effectively hangs the machine.

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