一种实用型粗糙面六参数双向反射分布函数模型

通过对五参数半经验双向反射分布函数(BRDF)模型进行修改,并吸收其它模型的优点,提出了一个六参数BRDF模型,该模型形式更简单,拟合效果更好,并且模型满足了能量守恒和互易性,使该模型更趋于实用化。利用模拟退火算法对多种不同样片的BRDF进行了拟合建模,获得了相应模型的参数值和偏差,结果证明了该模型的正确性,尤其适合对散射特性较弱样片BRDF的拟合建模。对于散射特性较弱的样片,与常用的五参数模型进行了比较,该模型的漫反射部分拟合效果更好,总体精度还略有提高。最后,为了更直观地表示目标样片的BRDF,分别给出了各个角度BRDF的三维拟合图。

Practical Six-Parameter Bidirectional Reflectance Distribution Function Model for Rough Surface

By modifying five-parameter semiempirical model of bidirectional reflectance distribution function (BRDF) and absorbing the advantages of other models, a six-parameter model of BRDF is proposed. The model, with simpler expression and better fitting effect, satisfies both reciprocity and energy conservation properties of BRDF, which enables the model to be practical. Simulated annealing algorithm is carried out on the statistical modeling of the BRDF of different samples, the corresponding model parameter values and deviation are obtained, the results verify the correctness of the model. According to the samples with weak scattering, which is especially suitable for this model, the diffuse component of the model has better fitting effect than that of the five-parameter model, and its total accuracy is slightly higher than that of the five-parameter model. Finally, to show the BRDF of the target samples visually, three-dimensional BRDF maps at differently incident angles are given.