The importance of including the Geoid in Terrestrial Survey Data Reduction to the Geocentric Datum of Australia

The complete reduction of terrestrial survey data to the Geodetic Reference System 1980 spheroid will become an important consideration after the implementation of the Geocentric Datum of Australia. Three examples are used to illustrate that when data reduction, which incorporates the effects of the Earth’s gravity field, is not applied, errors of approximately 10ppm, 200m and 3” can be introduced into terrain distances, astrogeodetic coordinates and azimuths respectively.