bakeMultipleScattering

Hillaire's isotropic multiple-scattering table Ψ(r, μs).

At each grid point: march a small bundle of directions, accumulating the second order of scattering (single-scattered light arriving from every direction, isotropic phase) and the transfer factor f — how much of what scatters here scatters again. The geometric series over orders collapses to Ψ = L₂ / (1 − f). The main march then adds Ψ·σs at every sample: all orders past the first for two multiplies and a lookup, which is the entire reason twilight has a sky instead of an edge.

recipeAtmosphereRecipe

Undocumented

transmittanceScatteringLut

Undocumented