Modeling The Characteristics Of Light Scattering From Target And Background On The Earth

In this paper, various previous BRDF models, which include empirical models, geometrical optics models and theory models, are summarized and their merits and demerits are analysed. Both shadowing function and facet distribution function as statistical characters of rough surface are discussed besides simpled fresnel reflectance function. Then three models are developed ,which respectively are modified physical model, a model for very rough surface and exponent model. Secondly, typical approaches of studying on vegetation have included radiative transfer, four-stream, geometric optics, hybrids of two or more of these, and numerical simulation. Then we introduced several models for density or sparse vegetation, soil and desert. At last, hemisphere reflectivity and bidirectional reflectance distribution of some samples are measured through our experimental facility, after being analzed, the results are fitted with the models developed above using genetic algorithm to get the parameters. Models can agree to the experience data well.In fact, all the models have their merits and demerits and are applied to only some kinds of surfaces. For a specific surface, we need to select a suitable model or develop a new model to simulate it better. All scholars wish to find a model, which can be used in the abroad fields and simulate more exactly.