Vicente Sosa asks:
has anybody out there any experience transforming raster data
between projections?
Here is what I posted to the list last September:
I've just realised that Darrell McCauley's s.sample program solves the r.proj
problem! It might still be a bit involved, but the general flow would be:(i) in GRASS in the NEW projection, use r.stats -1gz to generate a list of
desired cell locations. Cell values will not be used so any layer can be used(ii) outside of GRASS use proj to convert this to a site list in the old
projection
(iii) in GRASS in the OLD projection use s.sample to generate a list of values
at the positions in the site-list
(iv) edit/awk this so that it can be swallowed by r.in.ascii - a small program
might have to be written to make this quick
(v) in GRASS in the NEW projection run r.in.ascii.Darrell has kindly implemented bilinear, nearest-neighbour and cubic
interpolators, and since it works in the "implicity indexed" raster domain, it
will run quick.
Simon Cox
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Dr Simon Cox __ \
CSIRO Exploration & Mining ,~' L_|\ Australian
39 Fairway, PO Box 437, ;-' \ Geodynamics
Nedlands, WA 6009 Australia ( \ Cooperative
Phone +61 9 389 8421 + ___ / Research
Fax +61 9 389 1906 L~~' "\__/ Centre
s.cox@dem.csiro.au W
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