Graphics Gems V (IBM Version)

V.3

Faster Ray Tracing Using Scanline Rejection

Möller Tomas,     Lund Institute of Technology Lund, Sweden. E-mail address: [e-mail]

Introduction

Ray tracing speeds may be improved (Weghorst et al. 1984) by testing the primary ray intersections. A preprocessing phase uses a hidden surface algorithm to find a visible object for each pixel. This gem presents a scanline-based first-hit speedup technique. Its added advantage lies in its reuse of geometry-based intersection testing, making for a more uniform implementation. It also works with different kinds of supersampling.

Figure 1 shows an overview of a simple viewing geometry. Assume that the picture is rendered one scanline at the time with increasing scanline number. Now consider ...