What do Happy Feet, Polar Express, the Lord of the Ringstrilogy, Beowulf, and The Strange Case of Benjamin Button have in common? They are all films that employ the latest advances in motion capture technology -- or rather, what was cutting-edge in motion capture back in 2007, when those films were first being made. Scientists continue to come up with breakthrough technologies to make Hollywood's special effects even more magically convincing.
First, a bit of (recent) history. Back in the early days of animation, directors had to use dozens of cameras filming from all possible angles around the actor to capture his or her movements. But Polar Express and Beowulf, for example (both directed by Robert Zemeckis), relied on the Shape Wrap II suit developed by Aesthetic Technologies Lab in 2007 to capture, say, the curvy form of Angelina Jolie as Grendel's monstrous mother, or the fluid movements of Tom Hanks' animated conductor in Polar Express.
The key is using fiber optics to essentially record how light bends around a body. Strips of fiber optic tubes snake around the actor's body, fastened at several key points, and then computer software tracks the movements based on data gleaned from motion sensors and wirelessly transmitted to the computer.
Computer scientists at Cornell created a modeling technique that same year to make animated blonde hair more lifelike by simulating light that reflects from each individual hair -- an effect that is difficult to recreate digitally. Their process traces rays of light from the source into the hair and processes that data to produce a map of where the light should be at various points in the hair. Now a simulation that used to take 60 hours of computation time can be done in less than 3 hours.
For Benjamin Button, the challenge was to find a way to show Brad Pitt's character aging backwards, while still allowing for realistic human facial expressions. The filmmakers used a new (in 2007) technology called Contour, in which glow-in-the-dark makeup is used to cover an actor's face in order to digitally capture the subtle muscle movement, wrinkles, and micro-expressions that could one day create realistic "synthetic actors." Here's Ed Ulbrich speaking at TED about how they digitally generated the "old" Benjamin Button's face:
And motion capture technology keeps advancing with new innovations. Last week a paper appeared in the Philosophical Transactions of the Royal Society in England, describing a new device -- developed by researchers at Newcastle University -- capable of retrieving dozens of stored movement sequences in a motion capture system's vast database in just minutes. That can save producers a lot of time (and money); hours can be lost searching through motion capture libraries for just the right sequence. With the Newcastle system, one simply "sketches" the required movement with a mouse or a pen, and the software searches for a similar sequence already in the motion capture library.
Scientists can also now create personalized simulations of living body parts, such as replicating someone's gait, or simulating the flow of blood through the heart is it contracts. One day it may even be possible to replicate complete, functioning human bodies in the 3D digital world, possibly eliminating the need or animal testing. Who knows what creativity such a technology could inspire in the next generation of films?