Transparent distributed processing for rendering

Rendering, in particular the computation of global illumination, uses computationally very demanding algorithms. As a consequence many researchers have looked into speeding up the computation by distributing it over a number of computational units. However, in almost all cases did they completely redesign the relevant algorithms in order to achieve high efficiency for the particular distributed or parallel environment. At the same time global illumination algorithms have gotten more and more sophisticated and complex. Often several basic algorithms are combined in multi-pass arrangements to achieve the desired lighting effects. As a result, it is becoming increasingly difficult to analyze and adapt the algorithms for optimal parallel execution at the lower levels. Furthermore, these bottom-up approaches destroy the basic design of an algorithm by polluting it with distribution logic and thus easily make it unmaintainable. In this paper we present a top-down approach for designing distributed applications based on their existing object-oriented decomposition. Distribution logic, in our case based on the CORBA middleware standard, is introduced transparently to the existing application logic. The design approach is demonstrated using several examples of multi-pass global illumination computation and ray-tracing. The results show that a good speedup can usually be obtained even with minimal intervention into existing applications.