算过于复杂是目前多数植被二向反射模型存在的一个突出问题。对冠层的各次散射、透射和地面土壤反射分别进行分析和考虑 ,建立各次反射光谱分量与叶面积指数的函数关系。在Verstraete (1 986 )的物理模型的基础上加上多次散射和土壤反射的分量 ,建立了基于多次散射的植被 土壤二向反射模型 ,并证明仅考虑前三次散射即可满足一般精度要求。该模型克服了原模型的不足 ,并可根据叶面积指数等参量直接计算二向反射率 ,避免了运算量巨大的叠代运算 ,故便于应用。实验证明 ,该模型具有较高的精度

It's a primary question for many Bi directional models of Canopy presently that it's difficult for them to be used in practice due to their complexity. In this paper, multi scatterings and transmission taking place in canopy of vegetation, and reflectance of soil are analyzed respectively, and then the functions between every component of scattering and LAI are put forward. Improving Verstraete's(1986) Physical Model of Bi directional Reflectance of Vegetation Canopy by adding multi scattering and soil reflectance in the model, a Bi directional reflectance model of canopy soil as proposed and it was proved that the model's precision can be satisfied only when the first three scattering being taken into account. The shortcoming of the original model has been overcome in this model, and Bi directional reflectance can be calculated directly according to LAI and some other factors, avoiding overlap calculation which results tremendous amount of computation, so the model is easier applied in practice. The precision of the model was verified by experiments.