TLDR: 1. You have a volume 2. This volume has a lightfield, so Intensity(x,y,z,theta,phi) has five DoF. (imagine yourself in an FPS game, for every [x,y,z] p

TLDR: 1. You have a volume 2. This volume has a lightfield, so Intensity(x,y,z,theta,phi) has five DoF. (imagine yourself in an FPS game, for every [x,y,z] position you can fly to, you have a "skydome" view [theta,phi] that you can pan around with your mouse) 3. Light along the same lines are indistinguishable in which depth they originated from (you can "slide" the light) 4. Therefore you can "flatten" one dimension from 5DoF to 4DoF, producing an "apparent emission shell" of the object. This shell is the Lumigraph.