Subsurface scattering (or
SSS), also known as
subsurface light transport (
SSLT), is a mechanism of
light transport in which light penetrates the surface of a
translucent object, is
scattered by interacting with the material, and exits the surface at a different point. The light will generally penetrate the surface and be reflected a number of times at irregular angles inside the material, before passing back out of the material at an angle other than the angle it would have if it had been reflected directly off the surface. Subsurface scattering is important in
3D computer graphics, being necessary for the realistic rendering of materials such as
marble,
skin,
leaves,
wax and
milk.