Calibration and validation of SAR interferometry for DEM generation

A complete interferometric SAR (InSAR) procedure for the generation of digital elevation models (DEMs) is described, stressing the InSAR geometric aspects. A new approach to transform the interferometric phases to terrain heights is presented, which aims at achieving an accurate geocoding of the InSAR-generated DEMs. It is based on a rigorous model that connects image space to object space and on a least squares (LS) calibration of the InSAR geometry with ground control points (GCPs). The procedure may include the fusion of data coming from ascending and descending pairs of SAR images. For this purpose, a simultaneous calibration of the geometry of different InSAR pairs is proposed. It allows reducing the number of required GCPs using tie points, in analogy with the photogrammetric procedures. The validation of two DEMs, one coming from an ascending ERS-1 SAR pair and the other one derived by fusion of ascending and descending ERS-1 data, is described paying attention to the atmospheric effects on the generated DEMs. (C) 2002 Elsevier Science B.V. All rights reserved.