Evaluation of parallel ray tracing algorithm using screen space subdivision for image generation system MAGG
✍ Scribed by Toshiyuki Kawai; Mitsuhisa Ohnishi; Junichi Abeki; Hironobu Ohnishi
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 733 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0882-1666
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✦ Synopsis
Abstract
To produce a realistic image at a fast speed, a parallel graphic generator MAGG using transputers and a graphic generation software using a parallel ray tracing algorithm have been developed. A screen space subdivision is sued for the parallel processing. To avoid the limitation of a local memory due to the object data, a necessary part of the data alone is transmitted to the local memory.
To avoid the reduction of the effect of the parallel processing due to the increase of the interprocessor communication, the overall object data are stored in the shared memory so that they are transmitted to the local memory at a high speed using a DMA. The load balancing is carried out by dividing the screen into many small sections, which are called subscreens and are sufficiently larger than that of the processors, and by allocating the load dynamically. This method requires an estimation of the appropriate number of subscreens before the execution. To avoid this difficulty, already allocated subscreens are redivided and reallocated.
The control of the reallocation is carried out adaptively by a message exchange. The proposed method makes the distribution of the load uniform even though there are only a few small screens and the method improves both the image generation time and the parallel processing efficiency.