Last fall, we examined real-time ray tracing performance in 3D modeling programs and discussed some of the promises and challenges surrounding the technology. At the time, there weren’t any hardware ray tracers on the market. That’s about to change. Imagination Technologies, the design firm behind the popular PowerVR GPUs that power a number of modern smartphones and tablets, is bringing two ray tracing cards to market.
The R2100 uses a single Ray Tracing Unit (RTU), is built on 90nm technology, and ships with 4GB of included DDR2. It can buffer up to 60 million triangles in main memory; Imagination Technologies states that the chip itself is capable of processing up to 80 million incoherent rays per second. List price is expected to be $ 795.
The R2500 (pictured top) is the R2100′s big brother. It combines two RT2 processors on a single board and quadruples the RAM to 16GB. Power consumption is surprisingly low in both cases — 30W for the single-chip card, with a peak of 60W for the dual-chip version. Caustic Visualizer software is available for Autodesk Maya, 3ds Max, and Rhino3D. Imagination Technologies Brazil SDK is also available for leveraging capabilities over and above those available in OpenRL.
Performance, according to Imagination Technologies, is 2-5x higher than what conventional CPUs offer. Even if performance was merely equal, overall power consumption would be far lower.
Compare the power consumption of these three solutions, which we tested last year, to the 40-60W maximum envelope for the RTU family, and it’s clear that Imagination Technologies’ solution would have a major advantage. Then again, the companies most likely to invest in workstation-class ray tracing hardware are likely able to handle the power consumption bills that go along with it.
After the discussions around ray tracing that’ve literally swirled for decades, it’s exciting to see real-world hardware finally ready to ship, but the impact of that hardware is far from certain. These cards require software support, they’re programmed using a separate language (OpenRL), and while they offer huge RAM pools compared to solutions from Nvidia or AMD, they also rely on the CPU for shading. Texture maps and other scene components are stored on the workstation’s main memory, to free the RTU’s RAM for large model storage.
When Ars Technica covered the announcement a few days ago, John Carmack himself dropped in to give his own impression of ray tracing in modern games and professional applications as compared to rasterization. According to him, the practical benefits of hardware ray tracing compared to rasterization are limited: “For any game that is not grossly GPU bound, a ray tracing chip will be a decelerator, due to the additional cost of maintaining dynamic accelerator structures… I am 90% sure that the eventual path to integration of ray tracing hardware into consumer devices will be as minor tweaks to the existing GPU microarchitectures.”
For all the challenges facing Imagination Technologies when it comes to creating a market for these products, they could evolve the hardware rapidly. A modern chip built on 28nm technology and leveraging GDDR5 would have vastly improved performance characteristics, though these would obviously draw more power. For now, though, the cards are clearly positioned as a compromise between cost and performance.