THE RADIOSITY METHOD IN OPTICAL REMOTE-SENSING OF STRUCTURED 3-D SURFACES

The radiosity method is a mathematical concept to describe the scattering of light between ideally diffuse (Lambertian) surfaces. The method presented takes reflections, transmission, and multiple scattering into account. Algorithms to find view factors and to solve the radiosity equations using the Gauss - Seidel iteration method are described. An example for a layered plant canopy model shows the relation between the radiosity method and radiative transfer. The application of the radiosity method to remote sensing problems of 3-D surfaces, e.g., calculation of a BRDF including internal shadowing effects is shown. Numerical results of radiosity calculations are compared with equivalent radiative transfer results. We conclude that the radiosity method is a valuable tool to model the transport of light in vegetative canopies as well as a tool to evaluate bidirectional reflectance characteristics of discrete leaf canopy structures, such as angular reflectance signatures.