In my previous blog/FAQ entry I noted that there will be a variety of ESF (Elevation Scale Factors) to be encountered for a given latitude and ellipsoid height.
In this arcane blog entry, I present the NGS Ellipsoid Reduction Method and a deep drive into the resulting differences for various flattening ratio values, compare results obtained with GRS80 vs. WGS84 ellipsoids, look at the scale of errors introduced by using the orthometric height instead of the ellipsoid height and provide links to additional resources.
Keep reading:
iG GPS 