Diffusion and Multiple Anisotropic Scattering for Global Illumination in Clouds

The diffusion method is a good approximation inside the dense core of a cloud, but not at the more ten uous boundary regions. Also, it breaks down in regions w here the density of scattering droplets is zero. We have enhanced it by using hardware cell projection volum e rendering at cloud border voxels to account for t he straight line light transport across these empty regions. We have also used this hardware volume rendering at k ey voxels in the low-density boundary regions to account for the multiple anisotropic scattering of the environm ent.

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