On the adjustment of combined GPS/levelling/geoid networks

A detailed treatment of adjustment problems in combined global positioning system (CPS)/levelling/geoid networks is given. The two main types of "unknowns" in this kind of multi-data 1D networks are usually the gravimetric geoid accuracy and a 2D spatial held that describes all the datum/systematic distortions among the available height data acts. An accurate knowledge of the latter becomes especially important when we consider employing CPS techniques for levelling purposes with respect to a local vertical datum. Two modelling alternatives for the correction field are presented. namely a pure deterministic parametric model, and a hybrid deterministic and stochastic model. The concept of variance component estimation is also proposed its an important statistical tool for assessing the actual gravimetric geoid noise level and/or testing a priori determined geoid error models. Finally, conclusions are drawn and recommendations for further study are suggested.