[OSRS-PROJ] French NTF projections translation from EPSG to PROJ.4

Frank Warmerdam warmerdam at pobox.com
Thu Jul 25 08:54:30 EDT 2002

Marc Jacquin wrote:
> Hi,
> I can't find out why in the EPSG definition file French projections (NTF
> (Paris) / France I to IV) cannot be translated into PROJ.4. In the EPSG file
> it's commented as "Unable to to translate coordinate system into PROJ.4
> format". Obviously the NTF geodetic system is recognized and Lambert Conform
> Conic too. Any help on this matter would surely be appreciated by French
> mapserver users.


Generally this happens when there is more than one approximation available for
a datum (to WGS84) in the EPSG tables, as the auto-translation code can't
decide which to use.  I also doubt that the EPSG to PROJ.4 stuff properly
accounts for non-greenwich prime meridians.

Have you tried preparing a PROJ.4 definition yourself?

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    | Geospatial Programmer for Rent

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