Analysis of backscattering behaviors for partially damaged buildings in VHR SAR images

In the recent years, new satellite SAR data with very-high spatial resolution are available for scientific studies. In the urban scenario, these data are of high interest. Because, they allow the detection of changes at fine resolution, such those affecting buildings. Thus, they represent a precious information for rescue activities. Here, we study and design a geometrical model for representing possible kinds of damages in buildings. Among the different kinds of damages, we focus the attention on the one associated to the façades visible from the SAR sensor. According to the model and by using a ray-tracing method (i.e., the electromagnetic propagation is approximated with optical rays), we develop an analytical model for the backscattering of partially damaged buildings and investigate their behaviors in multi-temporal VHR SAR images. Both surface and multiple-bounce contributions are considered and analyzed by varying geometrical parameters. The resulting single date and multi-temporal patterns are validated on Cosmo-SkyMed data acquired over L’Aquila before and after the seismic event that hit the city in March 2009.