Models of vegetation canopy reflectance and their use in estimation of biophysical parameters from reflectance data

A conceptual basis for the physics of the interaction of solar radiation with a vegetation canopy is presented, yarious factors which affect the reflectance from such a canopy are delineated. An overview of various canopy reflectance models which attempt to incorporate the physics of interaction through these factors is given. These models can be divided into four basic categories: geometrical models, turbid medium models for homogeneous canopies, hybrid (of geometrical and turbid medium) models for heterogeneous canopies, and computer simulation models. Techniques for estimating important biophysical parameters like leaf area index, leaf angle distribution, and canopy architecture, through inversion of these models are reviewed. Some directions for future research are suggested.