Space-borne Synthetic Aperture Radar (SAR) interferometry is a powerful tool for measuring movements on ground by exploiting phase differences of SAR images taken at different time instances. Two technologies and their applications are described: 1) The persistent scatterer technique uses stacks of typically 100 images taken over up to 10 years for assessing slow deformation processes, e.g. land subsidence, at an accuracy of better than 1mm/year. 2) Alongtrack interferometry is used to measure the velocity of vehicles for traffic monitoring. The potential of TerraSAR-X, the German radar satellite to be launched in 2006, for interferometry is discussed.
Artikelauszug / Extract:
1. SAR Interferometry
Synthetic Aperture Rader (SAR) interferometry (InSAR) exploits the phase differences of two or more complex-valued SAR images of the same area for information extraction about topography, temporal stability, or motion (for an InSAR review see, e.g. Bamler et al., 1998). A digital surface model can be generated using the across-track InSAR configuration, i.e. where the two images are taken by SARs spatially separated in the across-track direction by typically a few hundred meters (spatial baseline). Monitoring movements requires images taken at different time instances (temporal baseline). In the paper we will discuss two extremes: 1) the assessment of slow deformation processes, e.g. land subsidence, and 2) rapid motion measurements for traffic monitoring. In the first application up to hundred images spanning a period of about 10 years are used, while for the latter application the time lag of the images is less than a millisecond.