-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Nils Faerber schreef: <snip> > I do not want to start nitpicking here but that solution is rather > inaccurate. It might serve as a first rough estimation but it neglects > the fact that the earth is not a perfect sphere. > The used so called ellipsoid model in GPS is WGS84 and should be taken > into account. There is no formula for calculating the distance on such > an ellipsoid but there are several algorithms to do so - sorry I do not > have one at hand right now... And if you find one, please check if the constants are right (e.g 20km difference between the axes, not 18km, 40.000 km circumference instead of 38.000, etc). I spent too much time debugging faulty IDL code that came with the support package to get the right perspective correction for images from a certain weather satelite. *shakes fist at EUMETSAT* regards, Koen -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (Darwin) iD8DBQFEsp2+MkyGM64RGpERAmsmAJ0UgZ+L7b+4DHrlt8zEfr6SVx0whQCaA+jf kk8Xa1uVs72DxcWKkQE8o7g= =RMjK -----END PGP SIGNATURE-----