The Hierarchical Ray Engine

Due to the success of texture based approaches, ray casting has lately been confined to performing preprocessing in realtime applications. Though GPU based ray casting implementations outperform the CPU now, they either do not scale well for higher primitive counts, or require the costly construction of spatial hierarchies. We present an improved algorithm based on the Ray Engine approach, which builds a hierarchy of rays instead of objects, completely on the graphics card. Exploiting the coherence between rays when displaying refractive objects or computing caustics, realtime frame rates are achieved without preprocessing. Thus, the method fills a gap in the realtime rendering repertoire.