From Newsgroup: comp.lang.misc
I imagine there are also open-source toolkits that cover this area. How do you compare with those?
GeoDLL is a Geodetic Development Kit resp. a program library and
funktions collection for worldwide 2D and 3D Coordinate Transformations
and Datum Shifts with highest accuracy and for calculating Meridian Convergence and many Extra Parameters. Furthermore: Helmert and
Molodensky Parameters, NTv2, HARN, INSPIRE, EPSG, Digital Elevation
Model (DEM), distance and Time Zone calculations and much more. GeoDLL
is available as 32Bit and 64Bit DLL and as C++ source code.
GeoDLL uses Coordinate Transformation formulas based upon EPSG
specifications and publications by Schatz, Schuhr and Klotz and
Hooijberg. Algorithms used for country-specific transformations are
either published or made directly available by the Measurement
Authorities of the respective countries or by similar respectable institutions. To achieve the highest precision only strong formula
algorithms are used for calculations.
Coordinate Transformations and Datum transitions by GeoDLL have
extremely high precision ranging within millimeters. A good example of geographic coordinates transformations between Gau|f-Kruger and UTM
Coordinate Systems made with GeoDLL are the results published by the North-Rhine Westphalia Land Survey Commission. It was confirmed that the differences were within the lower millimeter range.
For a statement about the accuracy were comparative calculations
realized with a set of test data of the "Arbeitsgemeinschaft der Vermessungsverwaltungen der L|nnder der Bundesrepublik Deutschland"
(ADV). It was confirmed that the differences were less then 0,2 millimeter.
Another interesting test series for a quality check was conducted by the German network operator Westnetz GmbH with an extreme NTv2 file. More
than 4.3 million points were transformed with TRANSDATpro / GeoDLL and
with a reference software from Gau|f-Kr|+ger/DHDN90 to UTM/ETRS89 and then compared. There were only very rarely deviations of more than one
millimeter. These only affected coordinates that were outside the scope
of the NTv2 file.
The test result and statements on the calculation speed and much more information can be found in our Publication area at
https://www.killetsoft.de/p_gdla_e.htm
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