(Mπ)2: A Hierarchical Parallel Processing System for the Multipass Rendering Method

Hiroaki KOBAYASHI  Hitoshi YAMAUCHI  Yuichiro TOH  Tadao NAKAMURA  

IEICE TRANSACTIONS on Information and Systems   Vol.E79-D   No.8   pp.1055-1064
Publication Date: 1996/08/25
Online ISSN: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Architectures, Algorithms and Networks for Massively Parallel Computing)
Category: Architectures
parallel processing systems,  global illumination models,  radiosity,  ray-tracing,  multipass rendering,  load balancing scheme,  cached frame buffer system,  

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This paper proposes a hierarchical parallel processing system for the multipass rendering method. The multipass rendering method based on the integration of radiosity and ray-tracing can synthesize photo-realistic images. However, the method is also computationally expensive. To accelerate the multipass rendering method, the system, called (Mπ)2, employs two kinds of parallel processing schemes. As a coarse-grain parallel processing, object-space parallel processing with multiple processing elements based on the object-space subdivision is adapted, and each processing element (PE) is equipped with multiple pipelined units for a fine-grain parallel processing. To balance load among the system, static load balancing at the PE level and dynamic load balancing at the pipelined unit level within the PE are introduced. Especially, we propose a novel static load allocation scheme, skewed-distributed allocation, which can effectively distribute a three-dimensional object space to one- or two-dimensional processor configuration of the (Mπ)2 system. Simulation experiments show that the two-dimensional (Mπ)2 systems with the skewed-distributed allocation outperform the three-dimensional systems with the non-skewed distributed allocation. Since lower dimensional systems can be built at a lower cost than higher dimensional systems, the skewed-distributed allocation will be meritorious. Besides, by the combination of static load balancing by the skewed-distributed allocation and the dynamic load balancing by dynamic ray allocation within each PE, the system performance can be further boosted. We also propose a cached frame buffer system to relieve access collision on a frame buffer.