Overview

In this last chapter, we cover a number of topics that are the subject of ongoing research. Indeed, the quest for realism and speed has not yet come to an end.

While deriving the rendering equation in Chapter 2, several restrictions were imposed on light transport. We assumed that wave effects could be ignored and that radiance is conserved along its path between mutually visible surfaces. We also assumed that light scattering happens instantaneously; that scattered light has the same wavelength as the incident beam; and that it scatters from the same location where it hits a surface. This is not always true. We start this chapter with a discussion of how to deal with participating media, translucent objects, and phenomena such as polarization, diffraction, interference, fluorescence, and phosphorescence, which do not fall within our assumptions. We need to refine our light transport model in order to obtain high realism when these phenomena come into play. Fortunately, most of the algorithms previously covered in this book can be extended rather easily to handle these phenomena, although some new and specific approaches exist as well.

Radiometry is, however, only part of the story, albeit an important part. Most often, computer graphics images are consumed by human observers, looking at a printed picture or a computer screen, or watching a computer graphics movie in a movie theater. Unfortunately, current display systems are not nearly capable of reproducing the wide range of light intensities that occurs in nature and that results from...