Upgrade Geodetic Model

[rdoddanavar]

Update Geodetic::update() routine to reflect more detailed models described in NGA.STND.0036_1.0.0_WGS84

[rdoddanavar]

From NGA.STND.0036_1.0.0_WGS84:

• In summary, for near-surface geodetic heights when sub-microgal precision is not necessary, the Taylor series expansion Equation (4-3) for γ h should suffice. When the intended application for γ h requires high accuracy, Equation (4-4) will be a close approximation to the exact Equation (4-16) for geodetic heights up to 20,000 meters. Of course, γ h can be computed using the exact Equation (4-16), but this requires that the computational procedure include the two transformations, R1 and R2, that are shown in Equation (4-17). Because the difference in results between Equations (4-4) and (4-16) is less than one microgal (10 -6 gal) for geodetic heights up to 20,000 meters, the transformation approach would probably be unnecessary in most situations. For applications requiring pure attraction (attraction without centrifugal force) due to the normal gravitational potential (V), the u- and beta-vector components of normal gravitation can be computed easily in the ellipsoidal coordinate system by omitting the last term in Equations (4-5) and (4-6), respectively. These last attraction terms account for the centrifugal force due to the angular velocity (omega) of the reference ellipsoid.