
THE DIGITAL FINITE ELEMENT HEIGHT REFERENCE SURFACE (DFHRS)
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The DFHRS research project of the Fachhochschule Karlsruhe-University of 
Applied Sciences is funded by the Ministry of Research and Education 
in September 2000.
The concept aims the direct conversion of ellipsoidal GPS-heights h 
into heights H of a standard height system (e.g. orthometric-, normal- 
or NN-height system) in an online or postprocessed GPS heighting by means 
of DFHRS data bases. It is based on the representation of the height reference 
surface by a finite element model. The DFHRS is carried by the base functions 
of bivariate polynomials set up in the meshes of an irregular grid and calculated
in a statistical control least squares adjustment.

The new DFHRS standard for GPS-heighting in DGPS-networks has been tested in 
several pilot-projects. DFHRS data bases have been produced for different German 
countries and are used in DGPS practice in the SAPOS-network. The results indicate 
accuracies less than 1 cm for the reproduction of standard heights H from ellipsoidal 
GPS-heights h.
Databases for other countries are in progress.
For more details see http://www.dfhbf.de.

For the use of the DFHRS within SKI-Pro, please read the German description "Install-DFHBF.pdf".
