Modeling and rendering heterogeneous fog in real-time using B-Spline wavelets

Heterogeneous fogs are often modeled with several layers of different density or using particle systems. However, layers are limited to vertical variations and using particles can involve long computation time with large outdoor scenes. In this article we present a simple method to render heterogeneous fog in real-time. The extinction function of our fog, related to its density, is first modeled in a B-Spline function basis. A wavelet transform is applied on this function to obtain a decomposition in both space and frequency domains. A grid traversal is used to render the fog in real time using GPU. Since no precomputation is required concerning the position of the camera or the fog, we can freely navigate or move the fog into the scene.