We've seen the specs, we've heard the pitches - but what we haven't experienced is any demonstration of a genuine next-gen vision. That changes today with Epic Games' reveal of Unreal Engine 5, accompanied by an astonishing tech demo confirmed as running in real-time on PlayStation 5 hardware. The promise is immense with the quality and density of the visuals on display almost defying belief. Imagine a game world where geometric detail is unlimited, with no pop-in and huge draw distances. Now picture this unprecedented level of fidelity backed up by real-time global illumination that's fully dynamic. It sounds too good to be true, but watch the video on this page and that's what's on display. This is next-gen and it's enormously exciting.
With Unreal Engine 5, Epic is looking to free developers from the constraints of poly counts and draw calls, to allow artists to simply drop in their full-fidelity ZBrush models and photogrammetry data. There's no need for simplifying models to hit performance targets, no need for LOD generation. The new UE5 system - dubbed Nanite - takes care of it for you. Meanwhile, full dynamic global illumination via Epic's new Lumen technology ensures accurate lighting of the scene with phenomenal realism.
What kind of detail levels are we talking about here? The 'Lumen in the Land of Nanite' demo includes a close-up on a statue built from 33 million triangles with 8K textures. It's displayed at maximum fidelity within the scene, with no developer input required. Moving into the next room, the demo wows us with almost 500 of those same statues in place (485 to be precise), all displayed at the same maximum quality. That's 16 billion triangles in total, running smoothly in-scene. It sounds impossible, but what next-gen delivers are the tools to deliver on an age-old rendering vision that seemed unattainable - until now. Along with other media outlets, we were pre-briefed by Epic Games and had the chance to put questions to CEO Tim Sweeney, CTO Kim Libreri and VP of engineering, Nick Penwarden.
"You know, the philosophy behind it goes back to the 1980s with the idea of REYES: Render Everything Your Eye Sees," says Tim Sweeney. "It's a funny acronym which means that given essentially infinite detail available, it's the engine's job to determine exactly what pixels need to be drawn in order to display it. It doesn't mean drawing all 10 billion polygons every frame because some of them are much, much smaller than the pixel. It means being able to render and an approximation of it which misses none of the detail that you're able to perceive and once you get to that point, you're done with geometry. There's nothing more you can do. And if you rendered more polygons, you wouldn't notice it because they just contribute infinitesimally to each pixel on the screen."
Put simply, the scene renders through UE5 on a triangle-per-pixel basis with the user seeing only what he/she needs to see. It sounds preposterously simple, but it's the culmination of over three years' worth of research and development headed up by Epic Games' technical director of graphics, Brian Karis. UE5 - on next-gen at least - is the realisation of the micro-polygon engine, and despite being demonstrated on PlayStation 5 specifically, Unreal Engine 5 is a cross-platform endeavour, just like its predecessors.
"The key features we're debuting will work across all of the next generation console platforms," adds Sweeney. "We don't have performance comparisons, we can't share performance comparisons, but this is a feature set you can count on with that generation, particularly micro polygon geometry with the Nanite technology and real-time global illumination with Lumen."
UE5 gets its first public release early in 2021 with franchise juggernaut Fortnite transitioning across from UE4 later on in the same year. Unlike UE4, however, the new iteration of the engine isn't a clean break from the past. It has the same system targets as UE4, meaning it'll run on anything from the most high-end PCs to old Android and iOS devices, encompassing current-gen consoles too - including Switch. Obviously though, you can't expect the same level of fidelity as the fully-fledged next-gen experience revealed today.
"To maintain compatibility with the older generation platforms, we have this next generation content pipeline where you build your assets or import them at the highest level of quality, the film level of quality that you'll run directly on next generation consoles," continues Tim Sweeney. "The engine provides and will provide more scalability points to down-resolution your content to run on everything, all the way down to iOS and Android devices from several years ago. So you build the content once and you can deploy it everywhere and you can build the same game for all these systems, but you just get a different level of graphical fidelity."
Epic is keen to stress a strong commitment to the interoperability of its new technology across multiple systems, despite demonstrating on PlayStation 5, where Sony has made strong arguments about the need for extreme bandwidth from storage. Meanwhile, Microsoft has developed DirectX 12 Ultimate, which also includes a radical revamp of how storage is handled on PC, but apparently the firm isn't leaning heavily on any one system's strength. However, subsequent to our interview, Epic did confirm that the next-gen primitive shader systems are in use in UE5 - but only when the hardware acceleration provides faster results than what the firm describes as its 'hyper-optimised compute shaders'.
"A number of different components are required to render this level of detail, right?" offers Sweeney. "One is the GPU performance and GPU architecture to draw an incredible amount of geometry that you're talking about - a very large number of teraflops being required for this. The other is the ability to load and stream it efficiently. One of the big efforts that's been done and is ongoing in Unreal Engine 5 now is optimising for next generation storage to make loading faster by multiples of current performance. Not just a little bit faster but a lot faster, so that you can bring in this geometry and display it, despite it not all fitting and memory, you know, taking advantage of next generation SSD architectures and everything else... Sony is pioneering here with the PlayStation 5 architecture. It's got a God-tier storage system which is pretty far ahead of PCs, but on a high-end PC with an SSD and especially with NVMe, you get awesome performance too."
But it's Sweeney's invocation of REYES that I'm particularly struck by. The UE5 tech demo doesn't show extreme detail at close range, it's also delivering huge draw distances and no visible evidence whatsoever of LOD pop-in. Everything is seamless, consistent. What's the secret? "I suppose the secret is that what Nanite aims to do is render effectively one triangle for pixel, so once you get down to that level of detail, the sort of ongoing changes in LOD are imperceptible," answers Nick Penwarden. "That's the idea of Render Everything Your Eye Sees," adds Tim Sweeney. "Render so much that if we rendered more you couldn't tell the difference, then as the amount of detail we're rendering changes, you shouldn't be able to perceive difference."
And that, in a nutshell, is the definition of a micro-polygon engine. The cost in terms of GPU resources is likely to be very high, but with next-gen, there's the horsepower to pull it off and the advantages are self-evident. Rendering one triangle per pixel essentially means that performance scales closely with resolution. "Interestingly, it does work very well with our dynamic resolution technique as well," adds Penwarden. "So, when GPU load gets high we can lower the screen resolution a bit and then we can adapt to that. In the demo we actually did use dynamic resolution, although it ends up rendering at about 1440p most of the time."
Penwarden also confirms that the temporal accumulation system seen in Unreal Engine 4 - which essentially adds detail from prior frames to increase resolution in the current one - is also used in UE5 and in this demo. The transparency here from Epic is impressive. We've spent a long time poring over a range of 3840x2160 uncompressed PNG screenshots supplied by the firm. They defy pixel-counting, with resolution as a metric pretty much as meaningless as it is for, say, a Blu-ray movie. But temporal accumulation does so much more for UE5 than just anti-aliasing or image reconstruction - it underpins the Lumen GI system.
"Temporal accumulation, you know - more than just normal temporal anti-aliasing - it's is a huge part of how we're able to make things look as good as this," says Kim Libreri. "The global illumination, without a temporal intelligence, there's no way you could do it on hardware yet. We're actually doubling down on the understanding of how temporal can help us, and there's been so many huge improvements in quality because of having a temporal component. It's the way that we get close to movie rendering - without those samples (and they're not just necessarily pure screen-space samples, there's loads of things you can do to temporally accumulate), the GI would not work anywhere near as well as it does without it."
Libreri himself has an award-winning background in the movie business, an area where Unreal Engine 4 is proving increasingly influential. He's particularly enthused about the idea of a universal workflow that allows for assets of identical quality to be used in all areas. "A lot of this came from the fact that we have these two extremes. We have people making mobile games on UE4 and we have people making the Mandalorian on UE4 and trying to work out how can we have a unified way of everybody working, so there's not this pressure point," he says. "You know, people's time should be spent on making awesome games and awesome gameplay and not necessarily on the minutiae of asset creation, the tedium because we have these old techniques from over a decade ago that were necessary to be deployed to be able to produce your environments."
And to prove the point, the UE5 demo running on PlayStation 5 mostly uses full fidelity assets taken from the Quixel Megascans library - not the more simplified versions designed for video games using 8K textures. Liberi adds: "The proof of the pudding is that the environments in the demo... half of our environment team were standard, Epic-experienced environmentalists and the other half were brand new to the company, they came from the movie industry and they took to the engine like a duck to water because they didn't have to worry about this barrier or making normal maps, low resolution meshes to best emulate the high resolution... so it made a huge difference to our throughput."
And there ends Epic's next-gen pitch with Unreal Engine 5. For next-gen game development, unprecedented detail and lighting is combined with the tech to deliver insanely detailed assets at as close to full fidelity as rendering resolution allows, combined with revamped physics, animation and audio systems. Meanwhile, with concerns spiralling about the cost and effort required to deliver a true generational leap in visual quality, Epic's strategy is all about giving easy-to-use tools to all developers, while unifying the tech and the required assets to work from the smallest indie projects up to the biggest motion pictures. At the same time, Sweeney is promising a smooth transition from UE4 to UE5.
"We're on Unreal Engine 4.25 right now, which is the 25th in its series," he says. "And in upgrading to the UE5, the cost to developers and the complexity will be like going through a few of these minor version updates, which most developers go through every few months. We want to bring the community along and bring them along quickly so that you don't have stragglers who are stuck with previous generation features years from now."
Today's announcements go beyond Unreal Engine 5. Epic is opening up the online infrastructure that powers Fortnite to any developer who wants it, even if the game itself doesn't run on Unreal Engine and even if it's Steam-only. This includes access to Epic's server infrastructure and cross-play functionality that's officially sanctioned by all console platform holders. But it's the 'Lumen in the Land of Nanite' technology demo running on PlayStation 5 that's going to attract the biggest headlines and the most attention - and it's not surprising.
With some level of disappointment in the wake of last week's Xbox Series X gameplay reveal - which didn't seem to feature Series X or indeed much in the way of gameplay - there was some concern about the future of next-gen gaming: to what extent would the new consoles deliver a dramatic leap over the games we play today? The Unreal Engine 5 tech demo gives us an emphatic answer - a new level of detail and fidelity we've never seen before - and apparently, there's much more to come. Hardware accelerated ray tracing will be supported in Unreal Engine 5, for example, but it's not a part of the PS5 tech demo revealed today. We'll have more soon on this remarkable piece of technology, but in the meantime, enjoy this first taste of what the next generation can really deliver.
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