ABSTRACT
Real-time volumetric clouds in games usually pay for fast performance with a reduction in quality. The most successful approaches are limited to low-altitude fluffy and translucent stratus-type clouds. We propose a volumetric solution that can fill a sky with evolving and realistic results that depict high-altitude cirrus clouds and all of the major low-level cloud types, including thick, billowy cumu-
lus clouds. Additionally, our approach approximates several volumetric lighting effects that have not yet been present in real-time cloud rendering solutions. And finally, this solution performs well enough in memory and on the GPU to be included in a AAA console game. (See Figure 4.1.)
The standard solutions for rendering clouds in AAA console games involve assets of some kind, either 2D billboards, polar sky dome images, or volumetric libraries that are instanced at render time. For games that require a constantly changing sky and allow the player to cover vast distances, such as open world, the benefits of highly detailed assets are overshadowed by the cost of storing and accessing data for multiple camera angles, times of day, and lighting conditions. Additionally, the simulation of cloud system evolution is limited to tricks or fakes such as rotating the sky dome or distorting images using 2D noise.
