Does anyone know how to determine the tangent to a point on a wgs84 ellipsoid? In particular I'm trying to find the "geodetic center point" of a wgs84 ellipsoid based on a geodetic point on the surface.
Explanation attempt 1 : If I extend a line towards the inside of the ellipsoid which is perpendicular to the tangent at point 60N 000E it should intersect a point on the XY plane. If I moved east or west it would draw a circle around the spherical center point. I need to determine that point on the circle. Explanation attempt 2 : If you look at the image on the FG scenery co-ordinate system doc : http://www.flightgear.org/Docs/Scenery/CoordinateSystem/img7.gif If I extend the line BF it will intersect the XY plane at a specific point. What is this point? I've found the sg_geodesy functions very useful but they don't cater for every possible question. I may have been able to figure this out if it was plain spherical trig but the ellipsoid stuff is a bit beyond me. Are there any good sources that will walk me through ellisoid maths step-by-step? BTW : Two of the links to WGS84 info on the http://www.flightgear.org/Docs/Scenery/CoordinateSystem/CoordinateSystem.html page are broken. Thanks Paul _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
