Shaders

Physical Scatter

This shader performs three kinds of simulations which can be used together or independently:

Multiple-scattering estimation: the most accurate, uses a strictly deterministic simulation of photon tracing to record sites in an internal photon map. These sites are looked up at render time and an optimized ray marching technique estimates multiple scatter irradiance.
Single-scattering approximation: is based on light intensities, independent of photon mapping.
Diffusion theory: is applied to evaluate the contribution of photons in the deep layer.

The following scattering features are supported:

Simulate subsurface scattering materials both in still images and animations (although the fast shaders may be more suitable for animation).
Receive and continue subsurface scattering media caustics from the outside world.
Cast caustics from the subsurface scattering media to the outside world.
Specify both absorption and scattering coefficients. The resulting image will simulate correctly areas of absorption and areas of scattering. This is very important to get subtle color changes for example in milk from blue to yellow.
Perform scattering along the geometry.

misss_physical

    color "misss_physical" (
        color           "material",
        color           "transmission",
        scalar          "ior",
        vector          "absorption_coeff",
        vector          "scattering_coeff",     
        scalar          "scale_conversion",
        scalar          "scattering_anisotropy",
        scalar          "depth",
        integer         "max_samples",
        integer         "max_photons",
        scalar          "max_radius",
        boolean         "approx_diffusion",
        boolean         "approx_single_scatter",
        boolean         "approx_multiple_scatter",
        array light     "lights",
        integer         "mode"
        )
    version 4
    apply material, photon

The shader provides parameters for Optical Properties and Tuning. The shader has to be applied both as a material and a photon shader.

misss_physical_phen

    material "misss_physical_phen" (
        color           "material",
        color           "transmission",
        scalar          "ior",
        vector          "absorption_coeff",
        vector          "scattering_coeff",
        scalar          "scale_conversion",
        scalar          "scattering_anisotropy",
        scalar          "depth",
        integer         "max_samples",
        integer         "max_photons",
        scalar          "max_radius",
        boolean         "approx_diffusion",
        boolean         "approx_single_scatter",
        boolean         "approx_multiple_scatter",
        array light     "lights",
        integer         "mode"
        )
    version 4

This is a material Phenomenon with appropriate shader connections both to the material and photon slots. Its parameters and behavior are identical to misss_physical.