VCT has been around for a while, it's been integrated into UE4 at some point (Siggraph 2012 here [1]). In the end, the global illumination solutions they've ha

VCT has been around for a while, it's been integrated into UE4 at some point (Siggraph 2012 here [1]). In the end, the global illumination solutions they've had : * VCT [1], seemed real-time * Indirect Lighting Cache (similar to Tatarchuk's irradiance volumes), precomputed with their Lightmass tech same as UE3 I think * LPV (Light Propagation Volumes, contributed by Lionhead Studios) [2] * Distance Field GI [3] Global illumination in real-time is a hard problem, there's a lot of interesting research on it at the moment. [1] https://de45xmedrsdbp.cloudfront.net/Resources/files/The_Technology_Behind_the_Elemental_Demo_16x9-1248544805.pdf https://de45xmedrsdbp.cloudfront.net/Resources/files/The_Tec... [2] https://docs.unrealengine.com/latest/INT/Engine/Rendering/LightingAndShadows/LightPropagationVolumes/ https://docs.unrealengine.com/latest/INT/Engine/Rendering/Li... [3] http://timhobsonue4.snappages.com/distance-field-global-illumination http://timhobsonue4.snappages.com/distance-field-global-illu...