This is the code for our 2024 SIGGRAPH paper. It is based on the Tungsten renderer and we defer to Tungsten for general documentation.

A Gaussian process implicit surface is implemented as a new medium type, which allows for free-flight distance sampling. We use a track length estimator to compute transmittance. To account for "surface-like reflectance" at what are technically medium scattering events, we implement a new phase function that defers to a BSDF instance for scattering computations. We implement our own Gaussian process utilities. Spatially varying mean and covariance parameters can be specified in many ways, including via dense or OpenVDB-based grids.

In addition to the core code, src/tungsten-test contains many experiments and test executables.