projections in GRASS

[Simon Cox]

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
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