[Proj] WGS84 definition

[Oscar van Vlijmen]

> From: Martin Vermeer <martin.vermeer-hut.fi>

> As for Europe, that was just an example. Of course as an alternative,
> ITRF with time dependent transformations is possible in principle, and
> unavoidable on this precision level. This would be global in scope.

Does this imply that on our Christmas wish list for transforms in PROJ.4 is
a 14-parameter Helmert transform?
Hmm, can be done by the regular 7-param transform, taking care of the signs,
and including some epoch pre-calculation.
Not difficult. Read for instance the 5-page article:
"International Terrestrial Reference Frame (ITRF) to GDA94 Coordinate
Transformations", J. Dawson and J. Steed, Geoscience Australia, 2004
<http://www.ga.gov.au/image_cache/GA3795.pdf>
or if that doesn't work:
<http://www.ga.gov.au/servlet/BigObjFileManager?bigobjid=GA3795>

For NAD83 <-> ITRF transformations already several software and on-line
solutions exist.
See also the National Geodetic Survey (NGS)
<http://www.ngs.noaa.gov/>