> Proj doesn't do height conversions between geoid and ellipsoid > references. For that you should use a geopotential model, such as > EGM-96. You can use the link: > > http://sps.unavco.org/geoid/ > to estimate the geoid height for a given point. or the official (?) one at: <http://earth-info.nima.mil/GandG/wgs84/gravitymod/egm96/intpt.htm>