Terrasar-x: How Can High Resolution Sar Data Support the Observation of Urban Areas?

TerraSAR-X is a new German radar satellite that shall be launched in mid 2006. The expected lifetime is 5 years. It carries a high frequency X-band Synthetic Aperture Radar (SAR) sensor that can be operated in different modes and polarisation. The Spotlight-, Stripmapand ScanSAR-modes provide high resolution SAR images for detailed analysis as well as wide swath data whenever a larger coverage is required. Imaging will be possible in single, dual and quad-polarisation. TerraSAR-X will be an operational SARsystem for scientific and commercial applications. Today’s space borne SAR systems usually provide 25 m resolution that is suitable to separate built-up areas from other land use and therewith the delineation of the city bodies. The high resolution SAR data of the upcoming new SAR sensors like TerraSAR-X and Radarsat-2 will increase dramatically the level of details visible in the SAR images. The detection and mapping of buildings, city structures and infrastructure like roads and railways will be possible. These features are of interest for mapping and monitoring purposes. The high resolution further enables to derive meaningful texture measures. Polarimetry can be used to separate different backscattering mechanisms and therewith to improve classification results The very short revisit time together with the all weather capability make TerraSAR-X to a very useful source to assess disaster damage. SAR interferometry is one of the major applications of today’s SAR data and can also be applied to TerraSAR-X data. Here the range differences between the ground targets and the antenna’s position during the acquisition are evaluated. Ground motions can be derived by applying differential interferometry and persistent scatterer techniques. A prerequisite for interferometry is the correlation of the radar echoes. The degree of correlation can be estimated from the SAR data and can be utilized for classification and change detection purposes. High resolution, short revisit times and a ± 250m repeat orbit service will open new perspectives for the observation of urban areas.