Subsurface Scattering II

Yesterday we took a look at the way light enters the skin and scatters below the surface, creating an unmistakable glow.

Sculptors who create hyper-real figures know that in order to fool the eye, the surface layer of skin has to be somewhat translucent. That’s why the figures in wax museums look more real than painted plaster. Your eye instantly spots the difference.

This was always a problem for Duane Hanson’s (1925-1996) figures, which were made from cast fiberglass and polyester resin. They were realistic in every other way, but the skin often had an unnatural opacity.

In the earlier days of movie animatronics, such as “Gremlins,” above, the skin was made of cast latex, which was a little too opaque, but now visual effects wizards generally use silicone when they need the surface to transmit and scatter more light.

Thomas Kuebler’s amazingly lifelike figures are made with a secret process using silicone. Note the subsurface scattering at the edge of shadow along the nose.

Ron Mueck, who makes realistic larger-than-life figures, uses silicone for babies, whose skin scatters light even more readily than adult skin.

The field of 3D animation and digital effects is developing the theory behind subsurface scattering. In the early Toy Story and Shrek films, it wasn’t possible to convey the effect, but now it has become a standard practice, and was used effectively in "Lord of the Rings."

Here are two images by Henrik Jensen, the first without subsurface light transport.

To get it right, computers have to be taught to consider density variations, form thickness, and light direction. Artists in the 3D animation field often get plenty of credit, but here we have to pay our grateful respect to the mathematicians, scientists, and programmers.

This is one of the reasons I’m glad to be a painter right now, and not in some past age. There’s a cross-fertilization of knowledge and technique happening between all these fields of art and science.
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Ron Mueck, link.
Thomas Kuebler, link.
Gremlins copyright Amblin Entertainment, link
Gollum copyright New line Cinema, link
CGI examples by pioneer Henrik Jenson (Thanks, Mr. Atrocity), link