VR has come a long way since the original Oculus Rift, but there’s room for improvement. Foveated rendering is an advanced technology found in few headsets, but rumor has it that the upcoming PSVR 2 headset from Sony has it as standard.
What Is “Foveated” Rendering?
We highlighted foveated rendering all the way back in 2018 as an important part of the future of VR, but years later it’s still an obscure concept. The main clue to what foveated rendering is, comes from its name. The fovea is the central part of the retina. The retina is the part of your eye’s anatomy that converts light to nerve signals, processed by the brain into the images you see.
Only the fovea offers a sharp and detailed vision. The fovea only accounts for between one and two percent of your visual field, so how is it possible that we perceive our visual field with so much clarity? The answer is that our eyes are constantly moving in a scanning pattern known as a “saccade.” By scanning the sharp sliver of our vision over the environment, our brains stitch together a high-resolution picture. You, of course, aren’t consciously aware of this process.
This is where foveated rendering (literally) comes into the picture. Why render the entire scene on-screen at maximum detail when the viewer can only see that detail in a tiny part of the screen at any one time? By tracking where the viewer’s fovea is pointed at any given moment, the GPU can redirect resources to that spot. This means the viewer sees a much higher quality rendered image than the available computer power is actually capable of.
Foveated Rendering Is Still Rare
VR headsets are the perfect platform for foveated rendering. Because the screen is strapped to your head in a fixed position, it makes tracking the fovea’s position relatively simple. That said, it still requires integrating relatively expensive eye-tracking technology into the headset, writing software APIs (Application Programming Interfaces), and developing game engines that can take advantage of the information.
As you can imagine, not many VR headsets you can buy today have eye-tracking for foveated rendering built-in. Despite this, VR hardware and software developers are clearly preparing for it.
For example, the Oculus Quest Software Development Kit (SDK) supports fixed foveated rendering. This is a related version of foveated rendering that doesn’t rely on eye-tracking but reduces rendering detail at the periphery of the image overall. As long as the user is looking at the central part of the screen, it works well enough, but looking around the VR world without turning your head will reveal lower quality elements of the image.
Making the Most of Console Power
Why would such a high-end feature in the VR world feature on a mainstream console VR platform? The main answer is that consoles like the PS5 have to survive for years with a fixed pool of processing power. When it comes to PC VR, it’s possible to keep upgrading to more powerful hardware, using brute force to achieve the desired image quality.
With the original PSVR for the PS4, Sony has already demonstrated that you can create triple-AAA VR experiences with minimal hardware if you work smart. Although the PS5’s specifications are impressive today, they’ll be pedestrian within a year or two, so building an efficient performance multiplier such as foveated rendering into the hardware is a sensible move even if it raises the initial hardware costs.
If we see another mid-generation upgrade in the same vein as the PS4 Pro, it still doesn’t solve the issue. After all, even if you have a more powerful console refresh, all software released for the platform still needs to run well on the original model.
A New Way to Interact in VR
Foveated rendering that uses eye-tracking brings more to the table than just more efficient rendering and better quality visuals. It allows for a new way to interact with VR worlds. If the software knows exactly where the user is looking within the scene, that information can be used as input. For example, it can help characters react to your gaze or trigger events, such as discovering a clue in an adventure game. That’s certainly just the tip of the iceberg when it comes to the potential uses developers will come up with. Still, before VR experiences and games can integrate these mechanics, eye-tracked foveated rendering needs a wide install base.
What If… Foveated Rendering Goes Mainstream?
When the PSVR 2 is finally revealed in its final form, and it does indeed have eye-tracking and foveated rendering baked in, that could change mainstream VR in dramatic ways. Consoles effectively set the minimum requirements for cross-platform development. The first PSVR represents one of the largest VR install bases, and the PS5 is selling as fast as Sony can make them. If PSVR 2 sells at least as well as its predecessor, there’s a strong incentive for VR game developers to take advantage of the system-level support for foveated rendering.
Should all of these developments fall neatly into place, it wouldn’t be surprising if the next generation of standalone and PC VR headsets also incorporate eye-tracked foveated rendering as a matter of course. If the PSVR 2 can push this next-generation feature into the mainstream, it’s going to benefit the entire VR industry.