Sort-Last is a computer graphics technique for rendering extremely large data sets on clusters of computers. Sort-Last works by dividing the data-set into even-sized chunks for parallel rendering and then composing the images to form the final result.

Since sort-last rendering requires the movement of large amounts of image data between cluster nodes, the network interconnecting the nodes becomes a major bottleneck.

In this paper, we describe a sort-last rendering system implemented on a cluster of computers whose nodes are connected by an all-optical switch. The rendering system introduces the notion of the Photonic Computing Engine, a computing system built dynamically by using the optical switch to create dedicated network connections between cluster nodes.

The sort-last volume rendering algorithm was implemented on the Photonic Computing Engine, and its performance is evaluated. Preliminary experiments show that performance is affected by the image composition time and average payload size. In an attempt to stabilize the performance of the system, we have designed a flow control mechanism that uses feedback messages to dynamically adjust the data flow rate within the computing engine.

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Kirihata, Y., Leigh, J., Xiong, C., Murata, T., A Sort-Last Rendering System over an Optical Backplane, CITSA, July 1st, 2004.