Physically correct transparency in real-time rendering

Abstract

Raster transparency remains both relevant and an open problem in computer graphics despite continuing advances in raster ray tracing and ray tracing hardware. Unlike opaque media, transparency encompasses numerous optical phenomena. Many dedicated rendering solutions exist for individual effects; however, implementing them in a single application may result in a monolithic and inefficient renderer. Furthermore, raster solutions are often lossy approximations of correctly evaluated transparency. The first problem would be eliminated by a unified raster transparency algorithm. To date, partially unified algorithms such as Phenomenological Transparency [96, 98] exist alongside other methods that are restricted to handling colour compositing and partial coverage [20, 14]. Generic or otherwise, a common subset of transparent phenomena is utilized for evaluation. Transparent emissives such as fire do not feature in these test cases: this indicates a gap in the literature despite extensive pre-existing work regarding the simulation of fire for rendering. This work seeks to contribute to these research areas by firstly investigating the improvement of the refraction approximation generated by Phenomenological Transparency with the intention of applying the method to the rendering of variable refractive fields. Secondly, it is intended to expand this investigation to include the previously unused emission parameter of the Phenomenological Transparency scattering model for transparent media.