On the Relationship Between Double Bounce and the Orientation of Buildings in VHR SAR Images

In this letter, we study empirically the relation between the double-bounce effect of buildings in very high resolution (VHR) synthetic aperture radar (SAR) and the orientation angle for two different ground materials (i.e., asphalt and grass) by analyzing two different TerraSAR-X VHR spaceborne SAR images. Furthermore, we compare our empirical results with the simulations obtained using theoretical electromagnetic models. In order to deal with slightly rough surfaces, we also present a novel model for double-bounce scattering based on the small-perturbation method. We show that the double-bounce effect results in different power signatures, depending on the type of the building and the surrounding ground properties. Finally, we discuss the reliability of theoretical models for predicting the double-bounce power for the analyzed data sets. The models can predict the general behavior of the double bounce but lack in calculating the accurate double-bounce radar cross section reliably.