Optical Models Geoff Wyvill and Craig McNaughton Abstract Artists make pictures that communicate ideas. It is not enough to point a camera and press the shutter. They must show us something individual about the way they see the scene they wish to portray. Why, then, has there been so much emphasis in computer graphics on rendering scenes with photographic realism? For most engineering applications, simple diagrams are sufficient. In this paper we explore the idea of modelling the eye of the artist. We introduce the idea of an optical model to describe the way in which what appears in a picture is related to what has been created in a three dimensional scene. Keywords: geometric modelling, ray tracing, optical models, animation. Introduction Every work of art is an act of communication. If you have no idea to communicate then you will not create art. It is not enough to portray the scene before you, you must show us something about it. Photography can be art but it usually isn't. Study a recent holiday snapshot and compare it with a picture from a fashion or travel magazine and you will see the difference between amateur and professional craftsmanship. Compare either with one of the published works of a great photographer like Cartier Bresson and you will appreciate the point without difficulty. Since the middle ages, and probably before that too, painters have researched and studied techniques to portray the world before them in a manner that we describe as realistic. They have also used these techniques to create, from the imagination, scenes and images that could not possibly be real. The need for technical mastery is exemplified by Renoir's saying: "Painting is first of all a manual job and one must be a good workman." (Lamboume 1965). T.-S. Chua et al. (eds.), CG International ’90 © Springer-Verlag Tokyo 1990