C# Class SharpMap.CoordinateSystems.Transformations.GeocentricTransform

Latitude, Longitude and ellipsoidal height in terms of a 3-dimensional geographic system may by expressed in terms of a geocentric (earth centered) Cartesian coordinate reference system X, Y, Z with the Z axis corresponding to the earth's rotation axis positive northwards, the X axis through the intersection of the prime meridian and equator, and the Y axis through the intersection of the equator with longitude 90 degrees east. The geographic and geocentric systems are based on the same geodetic datum.

Geocentric coordinate reference systems are conventionally taken to be defined with the X axis through the intersection of the Greenwich meridian and equator. This requires that the equivalent geographic coordinate reference systems based on a non-Greenwich prime meridian should first be transformed to their Greenwich equivalent. Geocentric coordinates X, Y and Z take their units from the units of the ellipsoid axes (a and b). As it is conventional for X, Y and Z to be in metres, if the ellipsoid axis dimensions are given in another linear unit they should first be converted to metres.