Improving efficiency of SBR method for complex shape aircraft targets

Calculation efficiency is the main limitation of shooting and bouncing rays (SBR) method for complex shape aircraft targets. An improving efficiency method is presented in aperture definition and intersection judgment. The facets data are translated into the incident coordinate system and projected on an incident plane. The ray zones are partitioned on the incident plane, and two endpoints of ray zones are found in all projection data. An assemblage of all zones is the aperture. More segments are given for complex shape aircraft targets on every ray zone to avoid rays which does no intersect with the target. After coordinate translation, the incident direction is parallel with one axis. Accelerate the first intersection judgment with grouping method. At the second intersection judgment and after then, target space is divided into visible and invisible areas. Only the facets of visible area need intersection judgment. This method is programmed and used for coupling complex shape aircraft targets. The effect of two acceleration methods is analyzed, and the effect of grouping length on grouping method efficiency is discussed. Results show that the efficiency of this method of complex shape aircraft targets is 7~8 times as much as the common SBR method.