[Proj] EPSG:28992 to EPSG:23031 conversion

Jean-Claude REPETTO jrepetto at free.fr
Wed Oct 8 17:41:49 EDT 2008

Frank Warmerdam a écrit :
> Bart van den Eijnden (OSGIS) wrote:
>> Hi Jean-Claude,
>> I am using PROJ 4.4.9 so that should not be necessary or am I mistaken?
> Bart,
> It is necessary if ED50 is non-trivially different from WGS84 though my
> understanding was that the differences were small.  I personally suspect
> the problem is either the sterea projection method (there are several
> variations of this I believe) or your towgs84 parameters are not ideal.

Differences between ED50 and WGS84 can be large. For example, in Spain :

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