NONLINEAR SPECTRAL MIXING MODELS FOR VEGETATIVE AND SOIL SURFACES

In this article we apply an analytical solution of the radiosity equation to compute vegetation indices, reflectance spectra, and the spectral bidirectional reflectance distribution function for simple canopy geometries. We show that nonlinear spectral mixing occurs due to multiple reflection and transmission from surfaces. We compare radiosity-derived spectra with single scattering or linear mixing models. We also develop a simple model to predict the reflectance spectrum of binary and ternary mineral mixtures of faceted surfaces. The two-facet model is validated by measurements of the reflectance.