Accurate treatment of geodesics
|Reported by:||karney||Owned by:|
OpenLayers 2.10 provides distVincenty and destinationVincenty which compute geodesics using Vincenty's method. However this method suffers from two problems:
- the distance calculation fails to converge from some pairs of points;
- where it converges the error is rather large (about 0.5mm).
OpenLayers also provides a function getGeodesicArea which is inaptly named because
- it treats only a sphere and not the ellipsoid;
- the edges of the polygon are not geodesics (or great circles) but rather straight lines on a cylindrical equal-area projection;
- the polygon cannot enclose a pole.
GeographicLib also provides facilities which may be useful to OpenLayers in the future (for instance it can simplify finding the intersection of geodesics).
GeographicLib using the MIT/X11 license so you are free to incorporate it into OpenLayers.