Geometric accuracy of ASAR products - Calibration Phase

Abstract

Geometric accuracy is a very important quality aspect of each remote sensing product, especially for use in combination with geographic information systems. The Processing and Archiving Facility for ERS-1/2 located at the German Remote Sensing Data Centre of the DLR together with research institutes in Graz und Zürich have implemented software packages for the geometric validation of SAR products from ERS and ENVISAT. The work is part of ESA’s Calibration and Validation activities and also supported by the agency. This paper describes the approaches and planned techniques for validation of geometric parameters. • Product format verification • Timing • SWST • Localisation accuracy • Geocoding parameters • Radiometric resampling effects • Consistency of the products • Inter-channel co-registration • Azimuth and ranging parameter • Orbit analysis • Optimisation • Temporal consistency The tests will be carried out in test areas, covering the four quadrants of the geographic co-ordinate system. Maps, ground control points, corner reflectors, digital elevation models and other remote sensing sources will be used for the geometric calibration. In addition, the standard ESA products will be compared with geocoded products generated from the project partners with their own software. The high-resolution image mode will first be tested, with the medium resolution and global monitoring mode following in the second calibration period. The orbit parameter accuracy can be verified by interferometric measurements. Given two sufficiently similar SAR images and a reference DEM we can use the speckle and phase information for timing parameter and orbit accuracy verification. We describe the methods and first results obtained from complex image mode products.