[Proj] Meaning of 7-parameter transformation rotations

[Martin Vermeer]

On Wed, Nov 30, 2005 at 12:58:19PM -0600, Clifford J Mugnier wrote:
> 
> 
> 
> 
> Gentlemen:
> 
> Note that the SENSE of the rotations have two common usages.  The American
> Standard versus the European Standard differ!  To transform in the same
> direction, the signs are OPPOSITE from one "standard" to another.
> Generally speaking, a 7-parameter  transformation, whether it is a
> Bursa-Wolfe or a Molodensky, MUST have a "test point" provided so that the
> user knows which sense the rotations need for the desired transformation
> direction.
> 
> The Americans, Australians, and Luxemborgs use one SENSE, the Europeans use
> the other.  In regard to the rest of the world, it depends on which
> brand-name of GPS Geodetic Processing software was used to derive the
> parameters from some collection of data points.  See my monthly column for
> such important minutiae for country to country considerations.
> 
> Be careful of 'dem signs!  :-)

Yes <sigh>, quite true. Perhaps it would be best to just add the matrix
equation in ASCII art to the text. 

- Martin 

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