Talk by Sebastien Hillaire at SIGGRAPH 2016 in the Physically Based Shading in Theory and Practice course.
Video games are becoming more and more demanding in terms of visual quality and dynamism. Open world games may require lots of visually dynamic elements, such as time of day lighting and real-time evolving weather. The dynamic and often global nature of these elements make them difficult to simulate and render in real time. Sky, atmosphere and clouds are the three main components we need to simulate in order to achieve dynamic time of day and weather conditions.
In this document, we present the practical physically-based solutions we have researched and developed for Frostbite to simulate, combine and render these complex and dynamic participating media elements. We present background on volumetric rendering, and then dive into the choices and improvements we have made to render each of these elements, as well as the complex interactions between them. We will also describe how this fits into Frostbite's physically based shading framework as well as how artists visually author each component to achieve their vision.