[Proj] Normal vector to a point on an Earth ellipsoid
Gerald I. Evenden
geraldi.evenden at gmail.com
Tue Feb 3 12:02:11 EST 2009
On Tuesday 03 February 2009 10:54:22 am Ung wrote:
> Hi All,
> Is there a function within Proj4 that would return a representation of a
> normal vector to a point on an Earth ellipsoid? Perhaps something like:
> getNormal( projPJ my_cs, double x, double y, double z )
> Would be grateful for any clues!
Sounds like an ENU coordinate but that is *not* part of a projection
operation. I will probably put a function like that in my geodesy library
but it is more related to XYZ geocentric system with a translation rotation
involved---translation of the geocentrin origin to a local point and rotation
about this point.
But an ENU has *nothing* to do with projections as the XY (Easting-Northings)
in projections have no relationship to the XY in EN even though the EN stands
It is unfortunate that the ENU designers stole the projected space
If you are just concerned with a z value you would have to "pass it around"
the projections operation.
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist
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