A Simplified Plane-parallel Scattering Model for Rendering Densely Distributed Objects such as Foliage

Abstract

Fast computation of multiple reflections and scattering among complex objects is very important in photorealistic rendering. This paper applies the plane-parallel scattering theory to the rendering of densely distributed objects such as trees. We propose a simplified plane-parallel scattering model that has very simple analytic solutions, allowing efficient evaluation of multiple scattering. A geometric compensation method is also introduced to cope with the infinite plane condition, required by the plane-parallel model. The scattering model was successfully applied to tree rendering. Comparison with a Monte Carlo method was made and reasonable agreement was confirmed. A rendering system based on the model was implemented and multiple inter-reflections were effectively obtained. The view-independent feature of the model allows fast display of scenes. The pre-computation is also modest, permitting interactive control of lighting conditions.