The application of fractal clustering to efficient molecular ray tracing on low-cost computers

Ray tracing is a powerful, and highly computer intensive means for generating high-quality molecular displays. A variety of simple, yet effective optimization strategies are described that allow large molecular models to be ray traced on microcomputers and low-cost desktop workstations. In particular, the method of fractal clustering provides a time and space-efficient means for spatially subdividing the molecular scene into a hierarchy of spherical bounding volumes, permitting ray-atom intersections to be determined by a form of binary search. An implementation of the algorithms, MolRay, is described which demonstrates that large structures may be ray traced in a reasonable time on a PC or small Unix workstation. Images generated by PC and Unix versions of MolRay are shown.