projection and extend through the pixel’s location on the
image plane, reaching out into the 3D world. Sampled 3D
points p along each ray are then passed through a Multi-
Layer Perceptron (MLP), which produces 4 scalar values as
output:

τ = fsoftplus (fMLP(p; θ)[1]) ,
ρ = fsigmoid (fMLP(p; θ)[2 : 4]) ,

(1)
Instant3D