Quality analysis of GeoDLL and TRANSDATpro with BeTA2007 test data of the ADV
Accuracy check of the software with excellent results!
Kempen, May 19, 2010
Killet GeoSoftware Ing.-GbR
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The program TRANSDATpro and the Geodetic Development Kit GeoDLL support NTv2 standard Coordinate Transformations with high accuracy. Amongst others the NTv2 gridfile BeTA2007 can be used for transformations within Germany with results in sub-meter accuracy. The gridfile is provided by the "Arbeitsgemeinschaft der Vermessungsverwaltungen der Länder der Bundesrepublik Deutschland" (ADV), along with a documentation and a set of test data. The test data contain 31 spaced points on the territory of the Federal Republic of Germany in different variations with coordinates in both Reference Systems DHDN90 and ETRS89.
The test data are provided by the ADV for the verification of the computational accuracy of transformation solutions with external software. The results do not make a statement about the accuracy of the transformation system BeTA2007. Due to the system with BeTA2007 a nationwide transformation accuracy in sub-meter range can be realized. For allocated areas even an accuracy in the decimeter and centimeter range can be achieved.
Comparative calculations with the test data of the ADV, done by the engineering office Killet GeoSoftware Ing.-GbR, attest to the software TRANSDATpro and GeoDLL a very good self-consistency. Here are the results:

1. Forward calculation Gauss-Krueger / DHDN90 to UTM / ETRS89:
   Maximum deviation 0,04 millimeters
   Average deviation 0,02 millimeters
2. Forward calculation Geographic Coordinates DHDN90 to ETRS89:
   Maximum deviation 0,51 microseconds (millionth seconds, corresponds appr. 0,01 millimeters)
   Average deviation 0,19 microseconds
3. Reverse calculation UTM / ETRS89 to Gauss-Krueger / DHDN90 on different meridian strips:
   Maximum deviation 0,20 millimeters
   Average deviation 0,07 millimeters
4. Reverse calculation Geographic Coordinates ETRS89 to DHDN90:
   Maximum deviation 0,51 microseconds
   Average deviation 0,18 microseconds

The good result is not surprising, since for the calculations strict formulas are used only. The Coordinate Transformations are performed according to publications of Maarten Hooijberg (1997 and 2008). The NTv2 date change is made following publications of D. R. Junkins and S. A. Farley (1995).
The comparative calculations were done with the program TRANSDATpro indeed, but they are also valid for the Geodetic Development Kit GeoDLL. These are used by the program TRANSDATpro for the necessary geodetic calculations. The libraries allow users to include Coordinate Transformations with high accuracy in their own programs.
You can download the test protocol and tables with the corresponding calculations by entering the URL https://www.killetsoft.de/zip/ntv2/bkg_ks.zip in your Internet browser.