The VolumePro real-time ray-casting system

Abstract

This paper describes VolumePro, the world's first single-chip realtime volume rendering system for consumer PCs. VolumePro implements ray-casting with parallel slice-by-slice processing. Our discussion of the architecture focuses mainly on the rendering pipeline and the memory organization. VolumePro has hardware for gradient estimation, classification, and per-sample Phong illumination. The system does not perform any pre-processing and makes parameter adjustments and changes to the volume data immediately visible. We describe several advanced features of VolumePro, such as gradient magnitude modulation of opacity and illumination, supersampling, cropping and cut planes. The system renders 500 million interpolated, Phong illuminated, composited samples per second. This is sufficient to render volumes with up to 16 million voxels (e.g., 256 3 ) at 30 frames per second.

Cell Projection of Meshes with Non-Planar Faces

“…For data specified on a regular grid, the ray tracing is straightforward [2,3,4,5], and similar effects can be obtained with 3D textures [6]. For curvilinear or irregular grids, these methods are only applicable after the data has been resampled.…”

Interactive Multi-volume Visualization

“…Specialized volume rendering hardware such as the VolumePro [14] has been available for realtime volume rendering for several years. Recent lower-cost consumer graphics cards such as the Nvidia GeForce 3 also support volume rendering through the use of volumetric textures [5].…”

“…The advent of texture hardware algorithms [2,5] and special hardware like the VolumePro [14] make possible interactive volume rendering which is very attractive to many disciplines. While previous volume visualization algorithms were mostly designed for looking at one volume at a time or for animating time-varying volume data [11].…”

A refined data addressing and processing scheme to accelerate volume raycasting

“…Two of them are hardware based; the first one utilizes commodity graphics-cards; the second one utilizes special purpose hardware, e.g. VolumePro and Vizard; the third is CPU based [1][2][3][4][5][6]. Purely hardware based solutions provide real-time performance and high quality; however they are limited in their functionalities: Basic visualization systems are supported by hardware volume rendering solutions; consequently they are the mostly applied approach in practice.…”