ABSTRACT
Light scattering effects in the atmosphere are crucial for creating realistic images of outdoor scenes. These effects generate the blue color in a clear sky as well as the spectrum of colors painting the horizon at sunset or sunrise. Light shafts, or god rays, are also produced by the same physical phenomenon when some sunlight is blocked by terrain features, such as mountains. Due to the complexity and numerous computations required to accurately evaluate the airlight integral, only rudimentary sky models are usually used in real-time rendering, which have a number of limitations. For example, simple models cannot handle daytime changes, restrict the camera to ground level, etc. Using screen-space imitation is a common technique to render god rays.
