unprojecting

Definition

Mapping a 2D image point back into a 3D ray or point using the camera's intrinsics and extrinsics. Projection discards depth on the way from 3D to 2D, so inverting it requires supplying that depth — from a prediction, from multi-view intersection, or from a learned prior — and a single view leaves it genuinely undetermined. How a method fills in the missing dimension is the main thing that distinguishes camera-based 3D perception approaches from one another.