Machine Design

They're alive!

They certainly look alive. The on-screen martial artists punch, block, jump, and land with all the visual queues that say, "This is real." Except it isn't. Reality comes from 3D body scans and motion capture that creates digitized humans with biomechanically correct skeletons and muscles for a Discovery Channel Xtreme Martial Arts (XMA) documentary.

Nexus Digital Studio combined scanned human characters with streaming motion-capture data and mapped moving, 3D characters onto 35-mm digitized film. In one scene, a character jabs a weapon into another's torso. The jolt to bones is shown through an animated x-ray technique mapped to the torso of a live-action martial artist. This creates an illusion that the bones and tissue were those of the live performer.

An Nvidia Quadro FX 3000 graphics card, capable of drawing more than 100 million triangles/sec, puts the digital acrobats into motion. The card comes from Nvidia Inc., Santa Clara, Calif. (

The documentary combines live-action fight sequences with physical and behavioral-based animation to illustrate the science of martial arts. The technique highlights moves normally impossible to analyze with the naked eye. A few video clips are available at

Each martial artist stepped into a laser scanner at Nexus Digital Studio to create a lifelike virtual model. With scan data comprising hundreds of thousands of polygons, the Nvidia card created a 3D image of each performer. Biomechanically accurate, animated skeletons were then scaled to fit the body size of the performers. As the artists fought, Motional Analysis Studios (MAS) used digitizing cameras to capture the subtlety and precision of the acrobatic moves. MAS used this behavioral data and graphics card to bring the 3D body scans to life by imposing natural movement onto the digitized characters.

"This combination of live-action footage, spectacular visuals, and biomechanically sound animation may redefine the way we look at human motion and bring it to the screen," says Mickey Stern, executive producer of XMA. "The entertainment value is self-evident, but the value for scientific study and learning is unlimited. Martial artists push their bodies to super-human levels, and only with the graphics card could we have measured and illustrated it down to bone and tissue."

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