If you look at georeference systems, they may fit a parametric equation with coefficients to a large set of earth data. The geoid in the link below is a refinem

If you look at georeference systems, they may fit a parametric equation with coefficients to a large set of earth data. The geoid in the link below is a refinement over an ellisoid (think lumpy potato vs smooth pebble), that gives you a 3D fit that has some level of accuracy with a very compact equation compared to carrying around the raw data. I'm thinking a supercomputer might be pretty useful to do the fit of data as it's updated, as well as giving options of using equations with different costs-to-fit on large data sets, or providing better fits on finer granularity. https://en.wikipedia.org/wiki/Earth_Gravitational_Model https://en.wikipedia.org/wiki/Earth_Gravitational_Model