[Proj] cs2cs's +towgs84 usage

Jean-Claude REPETTO jrepetto at free.fr
Fri Apr 23 07:39:15 EST 2010

Le 23/04/2010 14:24, Ilumas a écrit :
> Anyway, I believe that the behaviour of a certain towgs84 string is easy
> to test with cs2cs itself: just do the transformation to one direction
> (e.g. from WGS84) and convert the resulting coordinates back to the
> original datum using exactly the same parameter string. If the resulting
> coordinates equal to the original ones, no negation is needed. Right?
> ilumas


I think you are wrong. To check the parameters, you need to know the 
coordinates of at least one point in both datums, and compare them with 
the results of cs2cs.


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