The systematic analysis of the transformation between the German geodetic reference system (DHDN, DHHN) and the ETRF system (DREF91)

Jianqing Cai
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Abstract – The 69 colocated sites in the area of the West Germany are used to estimate the transformation parameters with the seven parameter similarity transformation model. According to the solutions of transformation parameters and corresponding residuals between DHDN and ETRF, detail analyses for global and regional transformation are performed, which show that the global accuracy of the transformation between DHDN and ETRF is ±5 m with WRMS (weighted root mean square) of±0.64mand regional transformations have much better fitting. Through the comparisons of estimated parameters of each state, the systematic differences in definition and observation among regional systems of DHDN have been confirmed. Practical usage of 7 parameter similarity transformation and some suggestions are pointed out.