Performance analysis of the TerraSAR-X Traffic monitoring concept

With TerraSAR-X, Germany will launch its first dual-channel SAR satellite mission in the year 2006. Besides other commercial applications TerraSAR-X should also be used as a demonstrator for traffic monitoring from space. This paper revises the theoretical background of traffic monitoring with space-based SARs and applies the conclusions to a performance analysis of the TerraSAR-X Traffic monitoring system. As it is well known, an object moving with a velocity deviating from the assumptions incorporated in the focusing process of the synthetic aperture radar (SAR) principle will generally appear both displaced and blurred in the image. To study the impact of these (and related) distortions in focused SAR images, the analytic relations between an arbitrarily moving point scatterer and its conjugate in the SAR image have been reviewed and adapted to the dual-channel satellite specifications of TerraSAR-X. To be able to monitor traffic under these boundary conditions in real-life situations, a specific detection scheme is proposed. This scheme integrates complementary detection and velocity estimation algorithms with knowledge derived from external sources as, e.g., road databases. The main focus of this article lies on an extensive analytical and empirical accuracy analysis for both vehicle detection and velocity estimation. The accuracy analysis includes a theoretical accuracy evaluation and a validation with real data.