[Proj] EPSG:28992 to EPSG:23031 conversion

[Jean-Claude REPETTO]

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 :
+towgs84=-131.0320,-100.2510,-163.3540,-1.2438,-0.0195,-1.1436,9.3900