[Proj] from EPSG:28992 to EPSG:25832

Frank Warmerdam warmerdam at pobox.com
Fri Mar 28 14:57:53 EDT 2008

Bart van den Eijnden (OSGIS) wrote:
> Hi Frank,
> thanks for this info, but this has quite some implications then or not?
> We would need to change quite some entries in the epsg file if we want 
> to get this right on a Mapserver WMS for instance.
> Any insight into why this was changed?


The old behavior was to do ellipse based conversions when no datum
information was available.  But this was causing frequent problems,
especially with spherical projections which are shifted very substantially
when moving to an ellipse (via transformation to/from geocentric coordinates).

It is possible that some epsg file entries should have towgs84=0,0,0
datum shift info added, but we already know that the epsg init file's
concept of datum shift values is very weak so I don't see that we are
in a noticably worse situation than we were, other than that it can
be a disruptive change.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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