Using stereo SAR and InSAR by combining the COSMO-SkyMed and the TanDEM-X mission satellites for estimation of absolute height

The objective of this work is to estimate absolute height in synthetic aperture radar (SAR) interferograms. Since height in interferograms is relative, we use stereo SAR with several satellites to achieve absolute height references of natural or man-made reflectors. We study the performance of stereo height estimation and geographic positioning using the satellites TerraSAR-X (TSX) and COSMO-SkyMed (CSK), both individually and in combination. Corner reflectors positioned by global positioning system (GPS) are used as reference. The accuracy obtained with corner reflectors may be the best we can expect using SAR for height estimation and geolocation. The location errors in this study were less than 0.6m for TSX alone, and 1.5m for CSK alone or combined with TSX. By combining TSX and CSK, stereo SAR is applied to estimate absolute height in bistatic interferograms generated from TSX and TanDEM-X (TDX). This method seems to yield absolute height accuracy in interferograms better than 1-2 m.