Optical models for direct volume rendering

摘要

This tutorial survey paper reviews several different models fornlight interaction with volume densities of absorbing, glowing,nreflecting, and/or scattering material. They are, in order of increasingnrealism, absorption only, emission only, emission and absorptionncombined, single scattering of external illumination without shadows,nsingle scattering with shadows, and multiple scattering. For each modelnthe paper provides the physical assumptions, describes the applicationsnfor which it is appropriate, derives the differential or integralnequations for light transport, presents calculation methods for solvingnthem, and shows output images for a data set representing a cloud.nSpecial attention is given to calculation methods for the multiplenscattering model