Local and Global Illumination in the Volume Rendering Integral

This article is intended as an update of the major survey by Max [Max, "Optical models for direct volume rendering.", IEEE Trans. on Visualization and Computer Graphics, 1(2):99–108, 1995] on optical models for direct volume rendering. It provides a brief overview of the subject scope covered by [Max, "Optical models for direct volume rendering.", IEEE Trans. on Visualization and Computer Graphics, 1(2):99–108, 1995], and brings recent developments, such as new shadow algorithms and refraction rendering, into the perspective. In particular, we examine three fundamentals aspects of direct volume rendering, namely the volume rendering integral, local illumination models and global illumination models, in a wavelength-independent manner. We review the developments on spectral volume rendering, in which visible light are considered as a form of electromagnetic radiation, optical models are implemented in conjunction with representations of spectral power distribution. This survey can provide a basis for, and encourage, new efforts for developing and using complex illumination models to achieve better realism and perception through optical correctness.