Predicting the Appearance of Materials Using Lorenz-Mie Theory

Computer graphics systems today are able to produce highly realistic images. The realism has reached a level where an observer has difficulties telling whether an image is real or synthetic. The exception is when we try to compute a picture of a scene that really exists and compare the result to a photograph of the real scene.

In this direct comparison, an observer quickly identifies the synthetic image. One of the problems is to model all the small geometrical details correctly. This is a problem that we will not consider. But even if we pick a simple experimental set up, where the objects in the scene have few geometrical details, a graphics system will still have a hard time predicting the result of taking a picture with a digital camera.

The problem here is to model the optical properties of the materials correctly. In this chapter, we show how Lorenz–Mie theory enables us to compute the optical properties of turbid materials such that we can predict their appearance. To describe the entire process of predicting the appearance of amaterial, we include a description of the mathematical models used in realistic image synthesis.