Ref-NeRF: Structured View-Dependent Appearance for Neural Radiance Fields (original) (raw)

We explicitly model object roughness using the expected values of a set of spherical harmonics under a von Mises-Fisher distribution whose concentration parameter varies spatially:

We call this Integrated Directional Encoding, and we show experimentally that it allows sharing the emittance functions between points with different roughnesses. It also enables scene editing after training. Theoretically, our encoding is stationary on the sphere, similar to the Euclidean stationarity of NeRF's positional encoding.