Imagination Demos Realtime Ray Tracing (Update: Video)

Imagination Technology hasn’t quite become a household name in the same way as ARM or Qualcomm, but you almost certainly own products powered by its chips. The most well-known is the PowerVR that runs graphics in Apple’s A-series SOCs, but they’re also behind h.264 and HEVC video decoders in some of Intel’s Atom chipsets for Android.

Moving Into the Big League

Additionally, chips using the MIPS architecture, which Imagination acquired in 2013, are found in a host of embedded systems, including Qualcomm’s Wi-Fi chips and MobileEye automotive cameras, which are used in the Tesla Model S’s driver assistance features.

Essentially, this paints a picture of a company focused on small embedded systems and mobile graphics. However, Imagination is poised to make a push into the desktop graphics space and seems to be bringing some serious hardware to the fight.

At its booth at CES, Imagination demonstrated the new PowerVR Wizard, a slim, single-slot PCI card. The Wizard has no active cooling and draws only around 10 watts of power at load. It doesn’t look like a powerhouse, but in a ray tracing head-to-head, it handily beat an Nvidia 980 Ti.

For those not familiar, ray tracing is an ultra-realistic way of rendering lighting, shadows, and reflections in a scene by individually calculating the paths of thousands or millions of light-beams. It’s used in Pixar movies to improve the looks of shiny surfaces, and it can be part of what makes those movies takes hours per frame to render.

The test was rendering a single, unmoving image of a robot, using ray tracing. Each rendering pass added more detail to the image and improved its quality. The PowerVR Wizard produced a decent image so fast it simply seemed to appear, while the 980 Ti had a noticeable delay and slowly gained detail. Overall, the Wizard completed render passes more than five times as fast than the 980 Ti.

In addition to the standard complement of compute and shader processing, the PowerVR Wizard is built with a dedicated ray-trace renderer. This lets it perform graphical tricks not usually seen in a full size card, let alone a low-power model.

Smoke and Mirrors (Albeit, Beautifully Rendered)

It should go without saying, but we weren’t able to get under the hood and see how these demos were set up and check their validity in real-world performance. Companies will always show you situations where their hardware is going to have an edge.

The test controlled for few enough variables that I’m still a little skeptical. The PowerVR was running on an Ubuntu system, and the 980 Ti was on Windows, using the open-sourced 3-D graphics software Blender and its Cycles Render Engine. The Ubuntu system was rendering through Resin and the Brazil render engine.  Imagination stated that Resin and Cycles use the same techniques for processing lighting and rays, and that the whole setup is open source. This should let you can verify the same rays are being processed by each system, but it’s undeniably a less than perfect test setup.

All of these caveats are grounds for a healthy dose of skepticism, but doubts aside, I’m still impressed that a 10 watt card could outpace a 980 Ti at any graphical task.

Another demonstration showed the potential of ray tracing in the Unity Engine. The setup had four PowerVR Wizards installed in one system, doing flythrough of a static scene with 300 million rays. The reflections and detail in the scene were impressive, and it played back at 1080 HD and a stable 30 frames a second. Imagination worked with Unity to add ray tracing options to its APIs, which the Wizard can take advantage of.

It wasn’t all quite so smooth. A demonstration on a single card of an animated scene hiccuped and fuzzed its way through a 720p playback, but it still showed some incredibly realistic reflections and surface textures.

Of course, for this technology to gain any traction, it needs to get into the next generation of devices. Imagination said the card is 28nm, but they are working on a smaller process node, which would drop the power envelope as low as 3 watts and make it suitable for tablets.

Imagination said it’s received interest from all three major console makers, as well as John Carmack of Oculus. When we asked if Imagination was looking to license the ray-trace engine out to existing graphics card companies, they wouldn’t comment.

Lowering the Overhead

Aside from this focus on ray tracing, Imagination is also trying to get their chips ready for the next wave of graphics APIs. A member of the Khronos group and supporters of OpenGL, Imagination has been working hard to make sure its chips and the upcoming Vulkan low-level API work well together.

A graphics demonstration flying over a field of gnomes was buttery smooth with almost no CPU impact under Vulkan, but it stuttered and chugged along at only a few frames per second on traditional OpenGL. The Vulkan demo also did a far better job spreading the workload, low that it was, across the four available threads, with OpenGL having a much greater impact on the first core.

Overall, Vulkan provided nearly a five-times increase in framerate, though the Imagination rep admitted this was a special case, and most applications will see a smaller gain.

Imagination is also working to make sure its products will get the same sort of boost from Apple’s Metal API -- no big surprise considering the PowerVR chips are in every iPad and iPhone.

All of these technologies will take some serious real-world testing to prove themselves, but for the sake of all of us having photo-realistic, perfectly ray-traced games on our tablets, we can hope they pan out.

Update, 1/8/16, 1:30am PT: We acquired new information regarding the rendering software the PowerVR was running, and removed a reference to the Ascend Mate 8. The article has been updated accordingly.

Update, 1/11/16, 1:30pm PT: Added video.

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