Overview

The world around us contains many beautiful phenomena. In the outdoors we can experience amazing sunsets, moonlight scattered through clouds, early morning fog at a lake, underwater sunbeams, and much more as described by Minnaert in his classic book [66]. If we move inside we can see flames in the fireplace, light focused through a glass of cognac onto a table, the translucent appearance of an orchid, steam rising from a cup of coffee, the soft flickering illumination from a candle flame. The list is endless.

Today we can simulate these phenomena with computers. The creation of realistic-looking synthetic images has reached a state that makes it possible to simulate almost any phenomena. We can render images of sunsets and sunrises using computers without having to wait for a clear day and the right time. We cannot yet reproduce the same experience as being outside observing a sunset, but this is mainly a limitation of the display devices available, and not a limitation of the underlying global illumination algorithms.

The last few years have seen an explosion in the use of computer graphics and realistic image synthesis. This is particularly the case in the entertainment industry where movies often make extensive use of computer-generated special effects that seamlessly integrate with real filmed footage. Computer games are presenting increasingly realistic worlds in real time getting closer to the dream of virtual reality. Outside entertainment, synthetic photorealistic images are used in design, architecture, hospitals, education, advertising, and more. These areas also...