[postgis-users] Question on transform.

[Frank Warmerdam]

Paul Ramsey wrote:
> Luis,
> You can confirm on the proj4 mailing list (try this out using the proj4 
> commandline tools) but my understanding is that proj4 mostly ignores 
> geogcs transforms. There are a few exceptions to this rule, but it is 
> mostly true, since proj4 was originally written without any geogcs 
> transform support at all. The support which is there was retrofitted in 
> later by Frank Warmerdam.
> Frank can correct me, of course... :)

Paul,

Well, I would note that PROJ.4 has support for 3/7 parameter datum shifts,
some grid file based datum and converting between geographic coordinates
systems with different ellipsoids.  It lacks some other datum shift mechanisms,
and has no concept of a prime meridian.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent