GPU Pro 6

222 III Lighting

3.3 Volumetric Fog Algorithm

Volumetric fog is an extension of existing ray-marching algorithms like in [T´oth

and Umenhoffer 09]. However, by decoupling and splitting typical ray-marching

steps and using intermediate storage, we aimed to solve the aforementioned dis-

advantages of classic 2D ray-marching solutions.

We based our algorithm on existing research on atmospheric scattering used in

the CGI industry and movies [Wrennige et al. 10] and computer games algorithms

using hardware volumetric 3D textures as an intermediate storage [Kaplanyan 09].

An article by Wrennige et al. describes how 3D textures and grids are used in

the VFX