NONLINEAR SPECTRAL MIXING MODELS FOR VEGETATIVE AND SOIL SURFACES

In this article we apply an analytical solution of the radiosity equat ion to compute vegetation indices, reflectance spectra, and the spectr al bidirectional reflectance distribution function for simple canopy g eometries. We show that nonlinear spectral mixing occurs due to multip le reflection and transmission from surfaces. We compare radiosity-der ived spectra with single scattering or linear mixing models. We also d evelop a simple model to predict the reflectance spectrum of binary an d ternary mineral mixtures of faceted surfaces. The two-facet model is validated by measurements of the reflectance.