In
3D computer graphics,
hidden surface determination (also known as
hidden surface removal (
HSR),
occlusion culling (
OC) or
visible surface determination (
VSD)) is the process used to determine which surfaces and parts of surfaces are not visible from a certain viewpoint. A hidden surface determination
algorithm is a solution to the
visibility problem, which was one of the first major problems in the field of 3D computer graphics. The process of hidden surface determination is sometimes called
hiding, and such an algorithm is sometimes called a
hider. The analogue for line rendering is
hidden line removal. Hidden surface determination is necessary to render an image correctly, so that one cannot look through walls in virtual reality.