Building a Full Scale VLSI-Based Volume Visualization System

The hardware realization of an advanced prototype of the Cube volume visualization system, Cube-3, is presented. The primary hardware component of Cube is a viewing and rendering multiprocessor with distributed 3D voxel memory. Cube-3 design is based on our experience with two earlier prototypes: Cube-1 realized in hardware using printed circuit board technology and Cube-2 our first custom-designed VLSI implementation. Both prototypes are of reduced-size resolution (163) and can generate only orthographic views. Cube-3 is the next generation prototype of a full-scale resolution of 2563 voxels. It has been functionally extended to generate non-orthographic projections, 3D real-time transformations, and shading. The ability to project and manipulate volumetric images in real-time is attributed to a unique skewed memory organization, a generalized skewed mapping, a special ray projection bus, a congradient shading technique, and a new barrel-shifting mechanism. This paper specifically describes the latter mechanism.