Real-time photorealism is the holy grail of gaming. And it’s coming to the PC sooner than you think , says Jeremy Laird

Today’s games can already achieve photorealism, but in fleeting moments.

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FROM THE VERY DAWN of computer graphics, there has been one overarching goal. An end game for PC gaming, a final destination. We’re talking of course about real-time photorealism. In experiential terms, graphics rendered in real-time that are indistinguishable from reality, at least as shown on a 2D screen. Achieve this goal and the observer will not be able to pick rendered computer graphics from real-life motion video. Of course, deciding when any given example of computer-generated graphics has achieved photorealism is always going to be a subjective call. We can all surely agree that the best CGI in movies and TV achieves that at least some of the time. But has any PC or console game yet achieved even fleeting photorealism? That’s debatable.

Just occasionally, you get a snippet of gaming, maybe something with an ultra-high detail texture pack installed, that momentarily breaches the photorealism barrier. If you’ve seen the Star Wars: Battlefront Real Life Mod in action you’ll know what we’re talking about. Occasionally, just for a moment, it can look photorealistic.

But here’s the thing. As you read these words, the PC graphics industry is taking what promises to be the last few steps towards what you might call sustained photorealism. Not photorealism all the time in every game. But sustained passages in certain games that can deliver what almost everyone would agree is photorealism. A huge array of technologies encompassing both hardware and software are currently aligning towards that end result. So get ready. Photorealism is coming to the PC, and sooner than you think.

Pre-rendered or in-game? Can you tell?

ONE WORD. PERFORMANCE. Ultimately, that’s what stands between gamers and truly photorealistic graphics. Since the first computers capable of rendering pretty much any graphics at all, it has all been about performance. Any computer capable of processing general-purpose instructions can render a graphical scene of any complexity you throw at it. Even a full ray-traced 8K vista rendered on an old 286 CPU, all 33 million pixels in ultra-high photorealistic quality, is doable—the only question is how long it takes to get the job done. It might take a few months to spit out a single frame but it’s still doing it.

Of course, exactly how long is acceptable for real-time gaming is what matters here. These days, most gamers don’t get out of bed for less than 60 frames per second. That means the full game scene is rendered and outputted to the display 60 times each second. Maybe you can live with lower frame rates. Maybe you prefer higher. But something in the region of 60fps is a decent rule of thumb.

If a single frame takes a second, a minute, maybe even an hour to render, it doesn’t matter how good it looks—you’re not going to be gaming. Performance is everything and the solution to that problem is twofold. Either add more performance in hardware. Or make a given rendering task easier and faster.

This brings us neatly to perhaps the most superficially straightforward way to improve performance and achieve that photorealistic end game, namely upscaling. There’s nothing new about the basic principle of taking a low-resolution image and mapping it to a larger resolution. It’s just that, historically, the results have been less than impressive.

That’s especially true in the digital era, where flat panel displays are unforgiving of generic spatial upscaling algorithms that average out data from a single pixel in a source image over several pixels in an upscaled one. The results in terms of image quality are typically soft and blurry, but from a performance perspective, the boost from upscaling can be huge.

To take an example, upscaling from 1080p to 4K is a quadrupling of pixel count. Using old-fashioned spatial upscaling approaches that have the advantage of adding little to no additional time to the image output process, that means a quarter of the rendering work for the GPU compared with native 4K rendering and far higher frame rates.