Virtual reality is a hot topic at this year's Game Developers Conference, and AMD has its head in the game, too. Today at the show, the chipmaker announced LiquidVR, a set of tools designed to bring about the holy grail of virtual reality: a "motion-to-photon" latency low enough to make the experience subjectively seamless—an effect VR aficionados call "presence."
AMD says this quest involves optimizations across "the entire processing pipeline," from the GPU to the display hardware on VR headsets. Here are the main features of the LiquidVR 1.0 SDK, in the company's own words:
- Async Shaders for smooth head-tracking enabling Hardware-Accelerated Time Warp, a technology that uses updated information on a user’s head position after a frame has been rendered and then warps the image to reflect the new viewpoint just before sending it to a VR headset, effectively minimizing latency between when a user turns their head and what appears on screen.
- Affinity Multi-GPU for scalable rendering, a technology that allows multiple GPUs to work together to improve frame rates in VR applications by allowing them to assign work to run on specific GPUs. Each GPU renders the viewpoint from one eye, and then composites the outputs into a single stereo 3D image. With this technology, multi-GPU configurations become ideal for high performance VR rendering, delivering high frame rates for a smoother experience.
- Latest data latch for smooth head-tracking, a programming mechanism that helps get head tracking data from the head-mounted display to the GPU as quickly as possible by binding data as close to real-time as possible, practically eliminating any API overhead and removing latency.
- Direct-to-display for intuitively attaching VR headsets, to deliver a seamless plug-and-play virtual reality experience from an AMD Radeon™ graphics card to a connected VR headset, while enabling features such as booting directly to the display or using extended display features within Windows.
The official LiquidVR page mentions cutting motion-to-photon latency to "less than 10 millisconds." That means delivering a solid 100 FPS to the user's eyes—and it's about in line with the target I heard Oculus quote at AMD's APU13 conference a couple years back. I seem to recall Oculus mentioning tricks like time warping, as well, which it said would enable low latencies without requiring the GPU to sustain triple-digit frame rates.
Developers (and users, too) can sign up to learn more about LiquidVR here. AMD has also posted a LiquidVR video on YouTube, but there's not much in there beside a back-to-the-basics explanation of how VR works.