The Homing Beacon issue 102 has as its title story the recent Sci-Tech win for the work on production ready subsurface scattering. Associate VFX Supervisor Christophe Hery, who will receive the award along with former ILM members Joe Letteri and Ken McGaugh, explains a little of the history and concept on the technique, originally started for Star Wars Episode II but used until Harry Potter and the Chamber of Secrets.
Here is the bit:
Through its use of digital doubles performing hazardous stunts or synthetic characters like Yoda the Jedi Master, Episode III will continue to blaze new ground in the development of believable computer-generated organic characters. One of the tools Industrial Light & Magic uses is subsurface scattering rendering -- a technique that was in early development for Episode II, and one that has garnered recognition from the Academy of Motion Picture Arts and Sciences. On February 14, Christophe Hery will represent ILM in receiving a special certificate of merit from the Academy as part of the 76th annual Academy Awards.
The technical award Hery will accept is one of nine that the Academy will give this year and represents a major leap forward in the effort to create photo-realistic images on screen. While Hery started working on subsurface scattering during the production of Attack of the Clones, the technique wasn't perfected in time to use on the digital characters in that film. Instead, the public saw ILM's first use of the technique on Dobby the Elf in Harry Potter and the Chamber of Secrets, later in 2002.
"The idea is to simulate the effect of translucency and depict how light penetrates inside the skin and scatters around the different tissues, then comes out at different points," Hery explains. "Traditionally in computer graphics, we've followed the idea that light shines on a particular point and bounces off the same point. Subsurface scattering allows light to go into a certain point and come out in different places. It opens the door to all different kinds of materials in computer graphics -- especially skin," he says.
For a simple example of the natural effect that subsurface scattering replicates, hold your hand up to a bright light and notice how light shines through your skin and creates reddish and yellow glows. That kind of detail, which was previously missing from CG techniques, is what subsurface scattering brings to digitally rendered characters.
Although the process was first used more than a year ago, the Academy carefully reviewed submissions for their merit before deciding which of the 14 submissions would receive an award. Thanks to ILM's work with subsurface scattering in films like The Hulk and the use of similar techniques by other visual effects companies to create successful digital characters, the last two years of film production have demonstrated that it is becoming increasingly possible to make photorealistic humans and other creatures with translucent elements such as skin, Hery says.
"It's possible to make these look like they belong to the world around them," he says. "We forget that what nature is doing is very complex. All the time (in computer graphics) you're pushing the envelope, you have to go to the next level. This is just one component -- one big component -- of rendering human skin."