Design of a Fast Voxel Processor for Parallel Volume Visualization

The basics of a parallel real-time volume visualization architecture are introduced. Volume data is divided into subcubes that are dis­ tributed among multiple image processors and stored in their pri­ vate voxel memories. Rays fall into ray segments at the subcube borders. Each image processor is responsible for the ray segments within its assigned subcubes. Results of the ray segments are passed to the image processor where the ray continues. The enu­ meration of resampling points on the ray segments and the interpo­ lation at resampling points is accelerated by the voxel processor. The voxel processor can additionally compute a normalized gradi­ ent vector at a resampling point used as a surface normal estima­ tion for shading calculations. In the paper the focus is on operation and hardware implementation of this pipeline processor and the organization of voxel memory. The instruction set of the voxel pro­ cessor is explained. A performance of 20 images per second for a 2563 voxel volume and 16 image processors can be achieved. CR Descriptors: C.l.2 [Processor Architectures]: Multiple Data Stream ArchitecturesParallel Processors, Pipeline Processors; 1.3.1 [Computer Graphics]: Hardware Architecture Graphics processors; 1.3.2 [Computer Graphics]: Graphics Systems Dis­ tribu1edlnetwork graphics; 1.3.7 [Computer Graphics]:Three­ Dimensional Graphics and Realism Animation Ray tracing; 1.4.10 [Image Processing]; Image Representation Volumetric.