Neural Radiance Field

NeRF represents a scene with learned, continuous volumetric radiance field $F_\theta$ defined over a bounded 3D volume. In a NeRF, $F_\theta$ is a multilayer perceptron (MLP) that takes as input a 3D position $x = (x, y, z)$ and unit-norm viewing direction $d = (dx, dy, dz)$, and produces as output a density $\sigma$ and color $c = (r, g, b)$. The weights of the multilayer perceptron that parameterize $F_\theta$ are optimized so as to encode the radiance field of the scene. Volume rendering is used to compute the color of a single pixel.