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These experiments show that without knowing the 
precise absolute satellite orbitography, we can 
automatically unwrap the experimental 
interferogram from relative baseline information. 
DEM such as partial SPOT DEM or sparse 
altimetry informations can be transformed into 
interferograms that can be used to unwrap the 
initial interferogram or small baseline data set can 
help and partially unwrap interferograms for large 
baseline data set. 
5. CONCLUSION 
To assess the operational potential of the SAR 
interferometry method for digital terrain modelling 
we presented different experiments using DEM 
generated from SPOT imagery. SPOT DEM 
represents good references and can be used in 
different ways. First, considering SPOT DEM as a 
“scene reference” we showed how it is possible to 
simulate some of the behaviors of simple 
interferograms. Then using results from SIRB data, 
we described how we can evaluate and compare 
altimetry information issued from Interferometry 
and SPOT DEM. Finally we presented some 
experiments showing that SPOT DEM or coarse 
altimetry information as well as multi-baseline data 
can help to unwrap accurate but ambiguous 
interferograms. 
With the coming data from satellites such as ERST, 
J-ERS or ALMAZ, interest in SAR interferometry for 
digital terrain modelling is rapidly growing. We 
believe that, after the theoretical studies already 
discussed, experiments like the ones we presented 
here reinforce the idea that interferometry can be a 
practical way to get DEM. 
6. ACKNOWLEDGMENTS 
We wish to thank J.P.L. scientists for the set of 
SIR-B images which enabled us to work on real 
spaceborne imagery. 
7. BIBLIOGRAPHY 
Gabriel A.K. and Goldstein R. M., Crossed orbit 
interferometry: Theory and experimental results 
from sir-b, Int. J. Remote Sensing vol. 7 pp 313- 
320 - December 1988. 
Lin Qian, Vesecky John F. and Zebker Howard A., 
Topography estimation with interferometric 
synthetic aperture radar using fringe detection, 
IEEE Trans. Geoscience Remote Sensing - 1991. 
Massonnet D. & Rabaute Th., Radar 
interferometry: Limits and Potentials, - 
presentation at PIERS, Boston 1991- Submitted to 
IEEE. 
Prati C., Rocca F., Guarnieri A. M., and Damonti 
E., Seismic migration for sar focusing: 
Interferometrical applications, IEEE Trans. 
Geoscience Remote Sensing vol. 28 pp 627-640 - 
July 1990. 
93 
Zebker H.A. & Goldstein R.M., Topographic 
mapping from interferometric SAR observations, 
Journal of Geophysical Research vol. 91 nO BS - 
October 1986.