Transmittance function mapping
Symposium on Interactive 3D Graphics and Games on - I3D '11
The Moving Picture Company (a) Cloud -100 steps -8 fps (b) TinPan Alley -500 steps -10 fps (c) GI-Joe * -50 steps -3000 lights -7min Figure 1 : Our algorithm introduces transmittance function maps for the computation of light scattering within participating media for both real-time using a GeForce GTX480 (a, b) and production rendering (c) using Pixar's RenderMan R . Abstract The interaction between light and participating media involves complex physical phenomena including light absorption and
... scattering. Media such as fog, clouds or smoke feature complex lighting interactions that are intrinsically related to the properties of their constitutive particles. As a result, the radiance transmitted by the medium depends on the varying properties on the entire light paths, which generate soft light shafts and opacity variations. Simulating light scattering in these media usually requires complex offline estimations. Real-time applications are either based on heavy precomputations, limited to homogeneous media or relying on simplistic rendering techniques such as billboards. We propose a generic method for fast estimation of single scattering within participating media. Introducing the concept of Transmittance Function Maps and Uniform Projective Space Sampling, our method leverages graphics hardware for interactive support of dynamic light sources, viewpoints and participating media. Our method also accounts for the shadows cast from solid objects, providing a fullfeatured solution for fast rendering of participating media which potentially embrace the entire scene.