The Scalable, Advanced Graphics Environment (SAGE) is a new high-end, multi-chip rendering architecture. Each single SAGE board can render in excess of 80 million fully lit, textured, anti-aliased triangles per second. SAGE brings high quality antialiasing filters to video rate hardware for the first time. To achieve this, the concept of a frame buffer is replaced by a fully double-buffered sample buffer of between 1 and 16 non-uniformly placed samples per final output pixel. The video output raster of samples is subject to convolution by a 5x5 programmable reconstruction and bandpass filter that replaces the traditional RAMDAC . The reconstruction filter processes up to 400 samples per output pixel, and supports any radially symmetric filter, including those with negative lobes (full Mitchell-Netravali filter). Each SAGE board comprises four parallel rendering sub-units, and supports up to two video output channels. Multiple SAGE systems can be tiled together to support even higher fill rates, resolutions, and performance.

This paper introduces the concept of Geometry Compression, allowing 3D triangle data to be represented with a factor of 6 to 10 times fewer bits than conventional techniques, with only slight losses in object quality. The technique is amenable to rapid decompression in both software and hardware implementations; if 3D rendering hardware contains a geometry decompression unit, application geometry can be stored in memory in compressed format. Geometry is first represented as a generalized triangle mesh, a data structure that allows each instance of a vertex in a linear stream to specify an average of two triangles. Then a variable length compression is applied to individual positions, colors, and normals. Delta compression followed by a modified Huffman compression is used for positions and colors; a novel table-based approach is used for normals. The table allows any useful normal to be represented by an 18-bit index, many normals can be represented with index deltas of 8 bits or less. Geometry compression is a general space-time tradeoff, and offers advantages at every level of the memory/interconnect hierarchy: less storage space is needed on disk, less transmission time is needed on networks.

An important component of many virtual reality systems is head-tracked stereo display.The head-tracker enables the image rendering system to produce images from a viewpoint location that dynamically tracks the viewers head movement, creating a convincing 3D illusion.A viewer can achieve intricate hand/eye coordination on virtual objects if virtual and physical objects can be registered [o within a fraction of a centimeter.Computer graphics has traditionally been concerned with forming the correct image on a screen.When this goal is expanded to forming the correct pair of images on the viewers retinas, a number of additional physical factors must be taken into account.This paper presents the general steps that must be taken to achieve accurate high resolution headtracked stereo display on a workstation CRT: the need for predictive head-tracking, the dynamic optical location of the viewers eyepoints, physically accurate stereo perspective viewing matrices, and corrections for refractive and curvature distortions of glass CRTs.Employing these steps, a system is described that achieves sub-centimeter virtual to physical registration.

Current affordable architectures for high-speed display of shaded 3D objects operate orders of magnitude too slowly. Recent advances in floating point chip technology have outpaced polygon fill time, making the memory access bottleneck between the drawing processor and the frame buffer the most significant factor to be accelerated. Massively parallel VLSI system have the potential to bypass this bottleneck, but to date only at very high cost. We describe a new more affordable VLSI solution. A pipeline of triangle processors rasterizes the geometry, then a further pipeline of shading processors applies Phong shading with multiple light sources. The triangle processor pipeline performs 100 billion additions per second, and the shading pipeline performs two billion multiplies per second. This allows 3D graphics systems to be built capable of displaying more than one million triangles per second. We show the results of an anti-aliasing technique, and discuss extensions to texture mapping, shadows, and environment maps.