Based on 3-D graphics hardware accelerator and Z-Buffer technique

graphic electromagnetic computing (GRECO) algorithm can efficiently resolve blanking difficulties and visualization problems of traditional electromagnetic calculation procedures.Therefore

GRECO algorithm is considered as one of the most efficient methods to acquire characteristics of high-frequency and electricity large-sized target.However

there are disadvantages of traditional GRECO algorithm

as follows:normal vector of target cannot be extracted accurately

calculation accuracy is affected by screen resolution greatly and multiple reflections cannot be calculated directly.As a result

traditional GRECO algorithm is limited for this reason and cannot be used in some region widely.The traditional GRECO is improved in this paper

so that the geometric information of pixel can be extracted accurately.Technique of off-screen rendering based on frame buffer object (FBO) is used for improving the algorithm.Then the normal vector of target can be obtained precisely and effectively.Traditional discriminated method of facet pairs is improved by using area projection/physical optics to adapt the computation of RCS multiple scattering.