Epic Games’ Tim Sweeney Explains Lack Of ‘SVOGI’ In Unreal Engine 4

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Epic Games impressed gamers back in 2012 when it showcased its latest game engine, Unreal Engine 4, with its Global Illumination support. The Elemental Tech Demo was a beauty to behold, however its latest version – which ran on Sony’s PS4 – did not feature any of it. Naturally, a lot of PC gamers blamed consoles for not being powerful enough to run this end-all-be-all feature. And in an interview with GameTrailers, Epic Games’ Tim Sweeney decided to shed some light on that matter.
In case you are not aware, Global Illumination refers to the calculation of light bouncing around a scene. Global Illumination is considered the holy grail of current/next gen lighting, and is responsible for the – real-life – glossy and metallic reflections. In other words, it’s a pretty important feature that most gamers have been looking forward to.
Epic Games’ Global Illumination technique is called Sparse Voxel Octree Global Illumination, a technique that was developed by Andrew Scheidecker. And despite what Epic Games showcased at last year’s GDC, it seems that this technique is too heavy for actual games.
As Sweeney told GameTrailers, that technique was extremely expensive. Therefore, Epic Games decided create a series of graphical effects that achieve the same image fidelity as SVOGI with far better performance.
This means that UE4 supports realistic real-time reflections, realistic specular lighting, and a combination of direct lighting with pre-computed Global Illumination.
As Sweeney stated, the aforementioned features enabled them to achieve that level of effects (of SVOGI) without all the cost.
Infiltrator was a good indication of what Epic can achieve with its latest version of Unreal Engine 4, and if games are going to look that good, then we obviously don’t mind the lack of the SVOGI (as long as developers take advantage of the alternative solutions that Epic introduced to its engine).
And regarding Crytek’s engine, yes; CryEngine 3 is the only engine – at this point – with proper dynamic Global Illumination. However, CryEngine 3’s light propagation volume is far less advanced than SVOGI. Not only that, but Crysis 3 has only one bounce GI and the sun is the only GI source.
All is not perfect for Epic Games though. A couple of days ago, we informed you about Epic’s issues with its Global Illumination alternatives. According to Epic’s rendering team leader, the company does not currently have a solution for dynamic GI in the fully dynamic lighting path, and this is something they hope to address in the future.
It would have been interesting to see a version of the Infiltrator Tech Demo with SVOGI enabled (even via brute force), in order to understand the gap, the differences and the performance hit between it and Epic’s latest workarounds. But that won’t happen anytime soon.