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Figure 5: Data fusion DEM results. Analysis of a profile along a slope which faces the ascending SAR antenna. 
3 | CONCLUSIONS 
A new InSAR procedure for DEM generation has been implemented. This procedure allows achieving an accurate 
geolocation of the generated grids and fusing data coming from multiple InSAR pairs. The analysis of the results 
showed strong correlation between DEM quality and image coherence, the degradation of the DEM quality in 
mountainous areas, and the importance of the atmospheric distortions. A suited strategy to reduce such distortions has 
been employed. In the analysed grids it increases considerably the DEM precision. The procedure has been tested 
deriving a DEM by ascending and descending data fusion. The data fusion gives good results in the areas affected by 
foreshortening and layover. 
ACKNOWLEDGEMENTS 
The authors thank Dr. Paolo Pasquali (now at RSL, University of Zurich) and Prof. Claudio Prati (from DEI, 
Polytechnic of Milan) for kindly providing the software for phase unwrapping, and Roman Arbiol and Fernando Pérez 
(from the Cartographic Institute of Catalonia) for providing the radargrammetric data used to compensate for the 
atmospheric effects. 
REFERENCES 
Crosetto, M., 2000. Calibration and validation of SAR interferometry for DEM generation. Paper submitted to the 
ISPRS Journal of Photogrammetry and Remote Sensing. 
Crosetto, M., Crippa, B., 1999. Interferometric SAR calibration. Proceedings of the ISPRS - Commission VI 
Workshop, 15-19 February 1999, Parma (Italy), IAPRS, Vol. XXXII, Part 6W7, pp. 193-201. 
Crosetto, M., Pérez, F., 1999. Radargrammetry and SAR interferometry for DEM generation: validation and data 
fusion. Proceedings of the CEOS SAR Workshop, CNES/ESA, Toulouse (France), 26-29 October 1999. 
Http://www.estec.esa.nl/CONFANNOUN/99b02/index.html. 
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