CD Projekt RED's Lead Engine Programmer Balazs Torok and Lead Technical Artist Krzysztof Krzyscin held a technical panel at Siggraph 2013 titled "Advances in Real-Time Rendering Course", explaining in depth the technology behind the RED Engine and their upcoming title The Witcher 3: Wild Hunt.

The presentation slides, that you can download here in Power Point format, are extremely interesting, and are a must see whether you're interested in the tech itself or you just want to check out some shiny work-in-progress models and renders of The Witcher 3. If you don't have a program that reads the Power Point format, you can just grab Open Office. Believe me, this presentation is worth the download.