Appendices

Forthenotations of directions, we use the convention that both the incident and outgoing rays point away from a scattering location. Spherical Harmonics (SH) are orthonormal basis defined on complex numbersovertheunitsphere. Since they were designed for scenes with solid objects, we adapt them to cope with participating media. Our implementation of the Neural Reflectance Field [2] baseline uses the same neural network architecture and positional encoding asinthe original paper. In addition, we employ a visibility MLP [3]tocompute a1-Dvisibility anda1-Dexpected termination depth.