The reflection of light from most materials consists of two major terms: the specular and the diffuse. Specular reflection may be modeled from first principles by considering a rough surface consisting of perfect reflectors, or micro-facets. Diffuse reflection is generally considered to result from multiple scattering either from a rough surface or from within a layer near the surface. Accounting for diffuse reflection by Lambert's Cosine Law, as is universally done in computer graphics, is not a physical theory based on first principles. This paper presents

Physically-based rendering methods represent the core of current realistic image synthesis frameworks. These methods, through a plausible simulation of the processes of light propagation and interaction with objects, have contributed considerably to the improvement of photorealistic rendering. The state of art research in this area includes the simulation of natural phenomena and the incorporation of biological aspects affecting light propagation in natural environments. The search for more efficient rendering solutions is also of major interest for the rendering community. In this dissertation biologically and physically-based models for light interaction with plant leaves are presented. Moreover, since the light that reach a plant leaf may be propagated directly from a light source or indirectly, due to multiple interactions with other objects in the environment, global illumination issues are also addressed, more specifically related to the radiosity method. This method is commonly...