Initial point selection and validation in PS-InSAR using integrated amplitude calibration

SAR amplitude calibration is performed prior to the selection of potential Persistent Scatterers (PS) to avoid amplitude variations due to sensor characteristics and viewing geometry. As only the interferometric phases of a small percentage of the radar pixels in an image is used in the PS-InSAR analysis, it is investigated if this time and storage space consuming step can be omitted. We present an integrated method which does not perform amplitude calibration explicitly, but integrates it into the PS point selection procedure for validation purposes by evaluating the hypothesis that a point would have been selected if all images were calibrated beforehand. Its performance assessment is based on coherent phase behavior of the selected potential PS and indicates that empirical calibration validation is an alternative for calibrating full images based on physical sensor parameters. I. INTRODUCTION Persistent Scatterer (PS) (1) InSAR is based on a network of point scatterers with a non-random phase behavior in time. As their interferometric phase contributions due to deformation are obscured by other effects, their identification is based on the amplitude behavior in time. For an unbiased selection of potential PS, a preceding SAR calibration is performed to isolate the amplitude observations corresponding with phys- ical PS properties from amplitude variations due to viewing geometry and sensor characteristics. Since the amount of PS is generally a small percentage of the full image and only their interferometric phase observations are used in the PS- InSAR analysis, the necessity of calibrating full images can be questioned. This study investigates the integration of amplitude calibration in the selection procedure of potential PS as a validation tool to determine if the potential PS would have been selected if the SAR images were calibrated beforehand.