Abstract: Graphical electromagnetic computing(GRECO)is one of the most promising methods to simulate the electrically large object scattering.But traditional GRECO algorithm can not directly calculate the bistatic RCS and multiple reflections. Moreover,the calculation accuracy is limited by the screen resolution.This paper presents a new method to reconstruct the geometric information from the information of pixels,by which the bistatic RCS and multiple reflections can be easily calculated accompanied with SBR.Meanwhile,by using the off-screen frame buffer object(FBO)method,GRECO's shortcoming of its calculation accuracy being dependent on the screen resolution is overcome.