The Playstation 4 Elemental Demo is here
The Unreal Engine is one of the most infamous game engines out there, and it’s various versions has been used to great effect on the PC, Xbox 360 and Playstation 3. Mass Effect and Gears of War series make use of the engine, and they are certainly not the only big titles to do so. But as technology expands, so can the engines and Epic Games have been hard at work on the new iteration of the engine, the not so imaginatively named Unreal Engine 4. We’ve seen snippets of what the engine is capable of by now, and I’m sure many readers have seen the Elemental demo that has been floating about since last year. It however was running on PC hardware, and not the Playstation 4.
The PC that was showing off the Unreal Engine 4 technology was pretty beastly – an Intel I7 CPU (so quad core, with Hyper Threading), 16GB of RAM, and last by no means least, a Geforce GTX 680 from Nvidia. There were some concerns due to the rather insane power of the combo of hardware that Sony’s new Playstation 4 wouldn’t be able to cope with it. The PS4 isn’t a slouch by any means – an AMD Jaguar with 8 Cores, running at 1.6GHZ, and 8GB of GDDR5 RAM combined with 18GCN cores (running at 800MHZ) provide the raw horsepower. These GCN cores (in case you happen to be unfamiliar) are the same cores powering the Southern Island range of AMD Radeon cores, the AKA the Radeon 7000 range.
However, the Playstation 4’s 18 GCN cores are a large cut down from the 32 of the 7970 (for reference, the Radeon 7970 desktop is roughly trading blows with the GTX 680 depending upon title). So some gamers might have been worried that the engine would need to undergo a hefty deal of cutting to be able to make it run on the hardware.
This isn’t exactly the case – although there have been a few changes from the full PC version – although I am pleased to say that the PS4 version is by no means ugly or bad in comparison, indeed it does a fairly decent job of replicating the I7/GTX 680. Now, fast forward several months until the GDC 2013 Playstation 4 conference and things Epic have gotten the engine up and running on the PS4.
So what changes has the demo undergone for the PS4?
There have been some alterations though. Sparse Voxel Octree Global Illumination (SVOGI) which the PC version of the demo was using could not make it onto the PS4, and there are a few changes in the LOD (level of detail) on textures too – but more on that in a minute or two.
“[SVOGI] was our prototype GI system that we used for Elemental last year. And our targets, given that we’ve had announced hardware from Sony, that’s where we’re going to be using Lightmass as our global illumination solution instead of SVOGI. We took advantage of the fact that we’d already written a distributed computation system for rendering it all out and we can add on features and refine it as needed. That’s been a really powerful tool for us to evolve our ability to render our scenes and pre-compute or re-compute anything we want.”
For those who’re unfamiliar with such technology, similar was used on last generation titles (such as Mass Effect 3) – but there have been significant improvements from the Xbox 360 and Playstation 3 generation.
There is a distinct difference in the levels of lighting on both the Playstation 4 and PC versions of the title – blacks on the Playstation look a lot darker, although there are some areas that have less “lighting”.
There are differences on the various levels of detail on the rocks and cracks, as well as other details such as the amount of snow in various scenes too. Objects in the distance appear with different levels of details. Check out the below couple of screen shots to see further differences between the Playstation 4 and PC versions. If you want more details I would recommend checking out the video linked earlier on in this article!
The technique is known as SVOGI – Sparse Voxel Octree Global Illumination, and was developed by Andrew Scheidecker at Epic. UE4 maintains a real-time octree data structure encoding a multi-resolution record of all of the visible direct light emitters in the scene, which are represented as directionally-colored voxels. That octree is maintained by voxelizing any parts of the scene that change, and using a traditional set of Direct Lighting techniques, such as shadow buffers, to capture first-bounce lighting.
Performing a cone-trace through this octree data structure (given a starting point, direction, and angle) yields an approximation of the light incident along that path.
The trick is to make cone-tracing fast enough, via GPU acceleration, that we can do it once or more per-pixel in real-time. Performing six wide cone-traces per pixel (one for each cardinal direction) yields an approximation of second-bounce indirect lighting. Performing a narrower cone-trace in the direction of specular reflection enables metallic reflections, in which the entire scene is reflected off each glossy surface.
And what of the Playstation 4 running the Infiltrator demo?
Of course, the Unreal Engine 4 elemental demo isn’t the only unreal tech demo that we’ve seen – there is also the infiltrator demo too. Although this has yet to be ported over to the Playstation 4, but there have been some comments regarding this already. The Elemental demo maybe impressive, but it’s of little match to the Infiltrator demo:
“A lot of the features that I showed you – thing like the reflections and the IES profiles – they’re all here,” he said. “As [the protagonist] steps through the cloaking field you actually see the boot reflected in the wet panelling below. And this is all throughout the demonstration. And some of them come across as somewhat subtle, but without them your eye would notice the difference.”
Willard mentioned that the Unreal Engine 4 Infiltrator Demo was running indeed running in real-time on the same PC hardware of elemental. It did so by adjusting layers and lighting as the demo played out. He further pointed out that sections of the demo that would have been nigh impossible without the new workflow Unreal Engine 4 offers.
“One thing to note – as the protoganist comes up to the city and we have a nice wide shot of the vista, that’s actually built out geometrically all the way out to the horizon line rather than having the equivalent of a matte painting as you’d see in a movie,” he explained. “We actually built that entire cityscape out, including the mountains. The only things that aren’t are the clouds that are embedded into the city. Everything else is full geometry from foreground to background.
As the physically-based materials inform the scene we end up with more and more things that are procedurally done… Because the end result is physically correct for the scene, we don’t need as much detail built into the base textures. Our materials system in conjunction with our physically correct lighting and shadowing really has a huge impact on the kind of time that we had to spend… We’re much more productive. We’re able to put a huge amount of detail in for a fraction of the time we would have spent to achieve the same level of detail – or not even been able to achieve in previous generations.”
So there you have it – a preview of things to come. This isn’t the end destination with this technology – especially as developers will get more accustomed to utilizing it, and different versions of the engine will come to light, which will improve things still further. If anyone is wondering, there have been no mentions yet as to the unreal technology working on Microsoft’s Xbox 720 console, aside from Epic commenting that they are focusing on next generation consoles.
It’s likely that the Xbox 720 will be able to run the engine too – although if it will be able to compete with the PC, or even Sony’s Playstation 4 remains to be seen – obviously it will all depend upon the hardware!