RENDERING MIRAGES AND OTHER ATMOSPHERIC PHENOMENA

Abstract

The past few years have seen some very impressive results in rendering natural phenomena. This paper addresses the problem of how to model and render optical illusions brought about by atmospheric refraction. Refraction of light in non-homogeneous media causes light rays to bend continuously, producing curved ray paths. Tracing these rays and determining their intersections with complex objects creates several difficulties. Our approach is to send rays through a virtual atmospheric object consisting of multiple air layers arranged in horizontal strata, with each layer having its own refractive index. This technique allows the use of line segments to trace curved paths. We give examples of applications to mirage effects.