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A Comparative Study of Radar Stereo and Interferometry for DEM Generation

Margrit Gelautz(1) and Howard A. Zebker(2)

(1) Vienna University of Technology, Favoritenstrasse 9-11/188/2, A-1040 Vienna, Austria
(2) Stanford University, 334 Packard Electrical Engineering, Mail Code 9515, Stanford CA, 94305-9515, United States


In our study, we derive and compare radar stereo and interferometric digital elevation models (DEMs) of a study site in Djibouti, East Africa. A Radarsat stereo pair, as well as Radarsat and ERS-2 interferometric data, comprise the test images. The primary objective of our experiment is to analyse and compare the results obtained by the two techniques and explore possible synergisms between them. We find that in regions of high coherence, the DEMs produced by interferometry are of much better quality than the stereo result. However, the corresponding error histograms also show some pronounced errors due to decorrelation and phase unwrapping problems on forested mountain slopes. On the other hand, the more robust stereo reconstruction, with an error standard deviation of 45m, is able to capture the general terrain shape, although finer surface details are lost. In the second part of our study, we demonstrate that merging the stereoscopic and interferometric DEMs by applying a user-defined weighting function to a filtered coherence map can significantly improve the accuracy of the computed elevation maps.


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Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry