This is from Digital Dragons 2013 event where Guerrilla Games held a presentation for Killzone SHadow Fall, in which Michael Drobot talked a few details on the lighting model in KZ SF.
So from what I can understand, there's a ray-tracing pass for real time reflection which subsequently leads to multiple bounces of reflections (holy sh*t talk about over doing). Apparently there's also GI bounce so there must be some kind of screenspace GI or something. I might have missed a few things too due to the guy wasn't speaking clearly or my lack of technical knowledge, I'm sure some of you here would pick up more from this clip. I know people have done ray tracing in Quake 4 or Wolfenstein but not in a game such as Killzone SF's caliber, pretty interesting stuff I must say
Andrespetmonkey said: I know ray tracing needs beastly highest of the high end hardware, so what's actually going on in the vid and what really do they mean when mentioning ray tracing?
Well he mentioned multiple reflections, which is really what ray tracing is about. Multiple might just mean "2" which would be the depth of the ray tracing. So basically, 2 reflections/refractions. (Not sure if he mentioned refraction tbh).
Basically, the more depth the better the scene. 2 reflections is okay, but ideally you would keep tracing reflections until the light is completely diminished. Obviously this would be much more taxing on your system and make real time ray tracing a fantasy at present.
Keep in mind each pixel is computed in this way. You send a ray from the pixel to the scene and computationally determine if there is an object intersection, which is then use to reflect/refract depending on the material of the object.