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7 Comparison with previous realization

This comparison evaluates the quality of older campaigns that contributed to the previous ETRS89 realisations in the Czech Republic than the quality of this campaign. However it is important to consider the discontinuity between previous and current national ETRS89 realisations.

The previous realisation of ETRS89 is described in Section 1. As a result, there exists a set of ETRS89 coordinates for 27 actually processed sites of the CZEPOS network in previous realisation. Table 9 shows translations and RMS errors estimated from Helmert transformation.

Nearly 1 cm offset in the North component is remarkable. Except that, the comparison shows a good agreement on a centimetre level in horizontal direction and a few centimetres in height. Only one station (CPRA) shows more than 15 mm difference in horizontal direction and two stations (CPRG and CMBO) exceed 30 mm in vertical direction.

Tab 9. Translations and RMS errors from Helmert transformations with respect to the previous ETRS89 realisation
Number of sites Translations RMS of Helmert transformation
North [mm] East [mm] Up [mm] North [mm] East [mm] Up [mm] Total [mm]
27 9.9 -1.7 1.1 5.3 6.5 15.6 10.2