Multi reference plane projected confocal 3-D imaging algorithm for CSAR

Three dimensional (3D) images can be obtained with SAR moving in a circular trajectory (circular SAR, CSAR) using confocal 3D imaging algorithm (CIA). However, the image formation is very time-consuming due to the 3-D space variant filtering contained in the algorithm. This paper transformed the 3D space variant filtering into a 2D filtering followed by a time shift in the height direction based on the small scale imaging area approximation and presented a projected confocal 3D imaging algorithm (PCIA) for CSAR. To cancel the restriction on PCIA, a multi reference plane projected confocal 3D imaging algorithm (MRPPCIA) was presented. It is found that the disadvantages of CIA such as complexity and inefficiency can be conquered by PCIA and the restriction on PCIA can be cancelled by adoption of MRPPCIA.