空间目标光学横截面积(OCSA)的准确计算是空间目标特性分析及识别的重要基础和前提之一。针对面元网格法计算OCSA实时性差，计算机图形学方法对材质的双向反射分布函数(BRDF)描述能力弱等问题，提出了一种基于OpenGL拾取技术的复杂空间目标OCSA计算方法。通过OpenGL拾取技术实现面元的一次遮挡判断，再基于改进Z缓冲技术实现面元的二次遮挡判断，在实现计算实时性的基础上保留了面元的详细信息，使高精度BRDF模型应用及OCSA精确计算得以开展。设计了嵌套式圆柱体和实际卫星模型并计算了其OCSA值，其中嵌套圆柱体OCSA的计算误差小于0.08%，在普通计算机上运行的平均耗时小于0.01 s，对卫星OCSA的计算平均耗时小于0.1 s，验证了本文方法的正确性和实时性。

The accurate optical cross section areas (OCSA) calculation of spatial objects is an important foundation and prerequisite for the analysis and recognition of spatial object characteristics. Aiming at the problems of the poor real-time performance of the grid model used in the faceting method and the weak ability for the description of bidirectional-reflectance-distribution-function (BRDF) of material by using the computer graphics method, an OCSA calculation method for complex space objects based on the OpenGL picking technique is proposed. The primary occlusion judgment of facets is realized by the OpenGL picking technique, and the second occlusion judgment between facets is realized based on the improved Z buffering technique. Therefore, the detailed information of facets is preserved without loss of real-time performance, which makes the application of precise BRDF model and the accurate calculation of OCSA possible. One nested cylinder and one satellite model are designed, and their OCSA value is calculated. The maximum OCSA error of the nested cylinder is less than 0.08% and the average time consumption on a general computer is less than 0.01 s. The average time consumption of OCSA for a satellite is less than 0.1 s. The results verify the correctness and real-time performance of the proposed method.