Monte Carlo ray tracing in optical canopy reflectance modelling

This paper reviews the use of Monte Carlo (MC) methods in optical canopy reflectance modelling. Their utility, and, more specifically, MC ray tracing for the numerical simulation of the radiation field within a vegetation canopy, are outlined. General issues pertinent to implementation and exploitation of such methods are discussed, such as the descriptions of canopy structure and radiometric properties required for their use. Strategies for the reduction of variance, which form the core of the application of MC methods to canopy reflectance modelling are presented, and examples given of the type of information which may be obtained from canopy reflectance modelling using MC ray tracing. The use of MC methods in the development of models of canopy development, driven by fundamental properties such as radiation interception are discussed.