[Proj] Lat-Lon values under different ellipsoides

Jan Hartmann j.l.h.hartmann at uva.nl
Tue Jan 27 10:45:41 EST 2009

Frank Warmerdam wrote:
> Jan,
> It is not meaningful to use +datum=WGS84 and an ellipse setting that is
> not WGS84.  The +datum=WGS84 expands internally into
> +towgs84=0,0,0 +ellps=WGS84 so your declaration will end up with two ellipse
> settings and which one gets selected will depend on order - a rather unstable
> situation!
> Best regards,

OK, I understand. I find the semantics of ellipses and datums in PROJ a 
bit confusing, but I understand how they came about and can work with 
them now.


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