Processing of Circular SAR trajectories with Fast Factorized Back-Projection

This paper describes the implementation of an efficient implementation of a Fast Factorized Back Projection (FFBP) algorithm for Circular SAR (CSAR) trajectories for real air- borne data. Unlike Fourier-domain based focusing processors, this approach considers the azimuth variance and topography changes with high accuracy, while improving significantly the computational time factor in comparison with the direct Back Projection (BP). To further accelerate the focusing, the circular FFBP was implemented also on a Graphics Processor Unit (GPU). In the second part of the document is shown a fully polarimetric image of the region of Kaufbeuren, Germany, (acquired by the DLR´s E-SAR system) focused with this method to the theoretical limit of ~λ/4 j. Thus, the efficiency, accuracy and performance of the circular FFBP is demonstrated, as well as the potential of CSAR when focusing over 360 °.