The role of the prediction stategies for the reliable transformation beetween two geodetic reference systems

One of he most common problems of the daily surveying/geodetic/cartographic practice is reliable transformation between two geodetic reference systems. There are plenty of well-known transformation’s models (e.g. 3D Helmert transdformation, 2D silimilarity transformaton, etc) applied for this purpose. Transformation scope is to optimally absorb the systematic inconsistencies of geodetic reference systems. In many cases, the pure deterministic approach is not sufficient, as the geodetic reference systems contain systematic effects, that are not successfully eliminated or reduced. Hence, a more sophiscticated methodology should be implemented, in order to enhance transformation’s accuracy. In this paper a case study is presented, including testing of  different deterministic transformation models between the old Greek Datum and the new official 1987 Hellenic Geodetic Reference System The estimated residuals do not fullfill the present needs of accuracy, thus we further implement some specified prediction models. The final outcome reads an improvement of the transformation between these two geodetic reference systems.