Analysis of the reliability of the double bounce scattering mechanism for detecting buildings in VHR SAR images

The double bounce effect of buildings is an important characteristic in very high resolution (VHR) synthetic aperture radar (SAR) images. It typically appears as a strong scattering mechanism caused by a corner reflector, which is made of the front wall of a building and its surrounding ground area. In order to exploit this feature effectively for automatic building detection and reconstruction techniques, empirical studies on real VHR SAR images need to investigate the stability of the double bounce mechanism with respect to changes in the viewing configuration and material properties. Thus, this paper addresses the analysis of the relation between the double bounce effect and the aspect angle of a building for two different ground materials, by analyzing two TerraSAR-X VHR spaceborne SAR images. Furthermore, we compare the empirical results with the simulations obtained by theoretical electromagnetic models. We show that if the buildings are surrounded by asphalt, the strength of the double bounce decreases significantly from 0 to 10 degrees aspect angle, while it decreases moderately for higher values of the aspect angle. Considering buildings which are surrounded by grass, the drop of the strength for low values of the aspect angle is less evident, but it is more constant on the full range of aspect angles.