Calibration and classification of ERS InSAR data over areas with slope variations

Abstract

During recent years signature analysis and classification of Interferometric Synthetic Aperture Radar data as well as estimation of geophysical parameters from SAR data have received an ever increasing interest, integrating the analysis of the backscattering coefficients with information derived from coherence maps.

An important requirement within these applications is the calibration of the SAR data, especially in areas with terrain variations, where active radar signals are distorted due to the projection of the scene topography into the slant range-Doppler plane. For this reason each pixel must be corrected, in terms of radiometry and phase, by taking also into account the position of the backscatter element defined by Digital Elevation Model data. This height information can be derived from InSAR or existing elevation models.

Only after these calibration and estimation procedures can one correctly perform the following steps of physical interpretation and classification of the data, combining images acquired across a long time interval, with variable weather conditions and different sensor geometries.

Both qualitative and quantitative results are presented and discussed, exploiting for this work a one year long time-series of ERS-1/2 Tandem data over a region in central Switzerland (Bern region). The results are compared with ground truth data of the area.

Keywords: InSAR, Coherence, Backscatter Coefficient, Calibration, Classification.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry