Translucent Material for Subsurface Scattering

I’ve created a translucent material type for Imagine which allows a more artist-friendly way of specifying the colour and transparency of translucent objects, without having to work out the very unintuitive (until you understand what’s going on internally) absorption and scattering coefficients that control the medium interaction for scattering events and the resulting transmission.

I’m pretty certain it’s not physically-accurate, but it seems to give pretty pleasing results, although I’m still not convinced of the correctness of my implementation, as it’s very easy to produce extremely noisy results.

I got a copy of Volume Rendering for Production for Christmas, so I’m going to be looking into heterogeneous volumes in the future.

Subsurface Scattering

I’ve just got Subsurface Scattering working via volumetric rendering with the Henyey Greenstein phase function. This method is completely cache-less (unlike the Dipole method), and I’m currently using single-scattering and attenuated direct illumination through mediums to work out the lighting.

The surface interactions aren’t currently physically-accurate, as I’m just using a diffuse (cosine-weighted hemisphere direction) transmissive BSDF (with no refraction) to allow rays to enter the mesh and the medium, instead of using the BSDF and any IOR of the medium to work out the entry direction through the surface correctly, but the results look pretty good, and most of the infrastructure’s in place now.