复杂外形飞行器目标的射线追踪法效率改进

Improving efficiency of SBR method for complex shape aircraft targets

针对计算效率是制约射线追踪（shooting and bouncing ray,SBR）法在复杂外形飞行器目标上应用的主要因素,在射线管口面确定和反射点求解两方面给出效率改进措施。把目标面元数据变换到入射坐标系中,在入射平面上投影并划分射线带,根据所有面元投影数据找到射线带的两个端点,所有射线带的集合即为射线管口面。对复杂外形飞行器目标在每个射线带上设置多个片段,完全避免不与目标相交的废射线管的产生。坐标变换之后入射方向与一根坐标轴平行,采用分组法加速第一次求交判断。在第二次及以后的求交判断中,根据射线方向将目标所在空间分为可见区和不可见区,仅对可见区的面元进行求交判断。对具有耦合特性的复杂外形飞行器目标进行了编程计算,对比分析了两种求交判断加速方法的效果,讨论了分组边长对分组法效率的影响。计算结果显示,该方法对复杂外形飞行器目标的计算效率为普通SBR法的7~8倍。

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.