[Proj] Re: WGS84 Lat Lon to XYZ convercion

Frank Warmerdam warmerdam at pobox.com
Fri Feb 1 11:03:21 EST 2008

Alekos Ntermaris wrote:
> The problem is that using the pj_fwd function i get the same results as 
> the input ( lon , lat) and not XYZ....


I haven't followed this thread closely, but you pj_fwd() and pj_inv() only
do geographic <-> projected transformations.  If you want to do a
transformation involving datum shifts or geocentric coordinates you should
be using pj_transform().

When you refer to XYZ coordinates, are you mean geocentric?  That is, meters
from the center of the earth in the x, y and z axes?  If so, you should
use +proj=geocent with pj_transform() or it's commandline equivelent cs2cs.

For example:

  cs2cs +proj=latlong +datum=WGS84 +to +proj=geocent +datum=WGS84
-117 55  (input)
-1664598.63     -3266958.75 5201383.52 (output)

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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