International Archives of Photogrammetry and Remote Sensing, Vol. 32, Part 7-4-3 W6, Valladolid, Spain, 3-4 June, 1999 
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The procedure needs no additional or reference data, as all input 
data comes from the generation processes and the DEMs 
themselves and can be obtained from common DEM generation 
software. This enables the operational implementation of the 
procedure and paves the way for a wide range of remote sensing 
applications needing accurate and reliable DEM information. 
The fused DEM can be reintroduced as a reference in the 
generation processes of the InSAR and stereo DEM, in order to 
increase their accuracy. This is of special interest for the InSAR 
phase flattening or coherence estimation, which is needed for 
the SAR retrieval of several bio- and geophysical parameters. 
ACKNOWLEDGEMENTS 
The work is a result of our studies within the EU ORFEAS 
project. The project was carried out in multi-national co 
operation with University of Thessaloniki, Politechnico di 
Milano, TU Graz, ETH Zurich, and Cartographic Institute of 
Catalonia, which provided a very complete dataset of the south- 
central part of Catalonia. I also want to thank Mr. Markus 
Niederost, IGP, ETH Zurich and especially Ms. Kirsten Wolff, 
Institute for Photogrammetry, University of Bonn, for their 
useful hints and discussions. 
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