基于应用光学中基本辐射理论，研究了临近空间高空气球的光散射特性。利用计算几何学的坐标转换以及网格划分建模思想，对高空气球球面进行网格面元划分。根据高空气球等透明类物体几何结构和物体光学特性，推导出透明类物体双向散射分布函数（BSDF）镜反射/折射、近镜反射/折射、漫反射/折射、理想漫反射/折射相结合的计算模型，最终得出高空气球散射背景辐射在地面产生辐射亮度的计算模型。利用MODTRAN 软件在3~5 μm和8~14 μm 波段仿真计算临近空间高空气球的背景辐射亮度，在0.24~2.4 μm 波段仿真计算气球自身亮度。仿真结果表明：利用BSDF模型计算得到高空气球亮度为2.28 × 10-3 W/(cm2·μm·sr) ，计算结果误差为10.6%，精度相对双向反射分布函数(BRDF)模型提高2%。在分析高空气球等类透明体散射特性时，可参考此模型来进行计算。

Optical scattering characteristics of high altitude balloon in near space are researched based on the fundamental radiation theory in applied optics. Facet of balloon in near space is created according to the general idea of coordination transformation and surface mesh-creation. A bidirectional scattering distribution function (BSDF) model is deduced by summing transparent object all scattering components, including specular reflective, near-specular reflective, diffuse reflective and random diffuse reflective components. A mathematical model of scattering characteristics of balloon in near space is built. An atmospheric modeling tool, MODTRAN, is used to model background radiance in the range of 3~5 μm and 8~14 μm and radiance of balloon in the range of 0.24~2.4 μm . The results show that the high altitude balloon radiance is 2.28 × 10-3 W ∕(cm2·μm·sr) , whose calculation error is 10.6% in use of BSDF model, and relative to bidirectional reflection distribution function (BRDF) model, the accuracy has an improvement of 2%. The modeling method of scattering characteristics of balloon in near space agrees with the modeling results, which proves the correctness of mathematical model.