A Comparison of Two Well Known Models for 7- Parameter Transformation

The transformation between two geocentric coordinate systems is carried out by the seven-parameter similarity transformation comprising three translations, three rotations and one scale difference. A number of approaches are available to realise this. Nevertheless, the Bursa-Wolf and Molodensky-Badekas models are generally favored for their simplicity. Except for their translations and their rms values both models yield similar results. Choosing a model producing more realistic translations is, of course, of paramount interest to surveyors. In this study, investigation of the causes of differences between translations of both models and which of these models produces more precise results is taken into consideration. The outcome of this investigation showed that the mathematical model of the Bursa-Wolf as opposed to the Molodensky-Badekas causes high correlations between transformation parameters, so Molodensky-Badekas model determines the translations better than the former.