NVIDIA is demonstrating its latest efforts in interactive ray tracing at SIGGRAPH 2008, using four next-generation Quadro GPUs in an NVIDIA Quadro Plex 2100 D4 Visual Computing System to show linear scaling during rendering of a complex, two-million polygon, anti-aliased automotive styling application. The images here are taken from the demo, which managed 30fps 1920 x 1080 High Definition video for an image-based lighting paint shader, ray traced shadows, reflections and refractions.
In NVIDIA's demo, rays are traced three times as they bounce through the scene. That number, though, is artificially capped by the company, and theoretically - with the GPU power to process it - could go even higher. Picture quality would therefore be a direct function of GPU power.
HotHardware speculates that the currently-available GeForce GTX 280, in a 3-way SLI configuration, could offer approximately 75-percent of the performance of this test system. They go on to predict that in perhaps 18 months high-end PCs could have the hardware to do real-time ray tracing, as in this demo, with fluid motion.