A fast shadowing test algorithm in physical optics based on spherical partition of target

Facets shadowing test is time-consuming and inefficient in calculation of radar cross section utilizing physical optics (PO). A novel method is proposed in this paper by covering the target by overlapped spheres which divide the facets to several consistent groups. In order to ensure that every facet is included by at least one sphere, the adjacent spheres must have a common area and some facets may be included by more than one sphere. Spheres' shadowing tests are conducted before the facets' tests. If one sphere does not shadow the facet under testing, then the facet cannot be shadowed by any facet within the sphere. Otherwise, every facet within the sphere should be judged whether to shadow the facet. Numerical simulation is conducted to validate the efficiency and accuracy of the algorithm. The spheres' size on performance of the algorithm is also discussed in this paper and an optional choice of the parameter is achieved resulting 89% time saving.