Application of radar space triangulation to the calibration of interferometric DEM

The generation of a digital elevation model (DEM) from a radar interferogram needs a planimetric and altimetric absolute registration, generally done with ground control points (GCP). Space triangulation (or multi-image localization) techniques allows one to create such control points when not available. The method consists in the coupling of both interferometric ascending and descending couples. First, a relative DEM is calculated from an interferogram. In a second step, a space triangulation technique is conducted with the crossed stereo-pairs in order to produce a control point network. This network is then used to improve the geo-localization and to absolutely calibrate the DEM. The aim of this paper is to present the results obtained at Alcatel Espace concerning the quality of the localization by space-triangulation and to conduct a quantitative analysis of interferometrically derived DEM. To perform this task, ERS 1/2 tandem SLC images are used in order to generate an INSAR DEM, located east of the city of Paris (Grand Morin basin).