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BACKGROUND: Ohio University's Aesthetic Technologies Laboratory records dance and other movement using motion capture technology, a method famously applied in such films as Lord of the Rings and The Polar Express. A suit called ShapeWrap II is the lab's newest resource for cross-disciplinary collaboration and fine arts innovation. It is also useful for physical therapy.
HOW IT WORKS: The ShapeWrap II suit uses fiber optic technology to track the movement of the wearer. The suit works with 3D imaging software to create digital animation. To record motion, the subject puts on a black elastic breastplate over his torso, fastened with Velcro. Then long strips of fiber-optic ShapeTape are added, running from the shoulders to the hands at feet, fastened around key body points like the biceps, thighs, and calves, and criss-crossing the waist like a belt. Finally, the ShapeHand glove links the subject's wrists to each fingertip and weight sensors strapped to the bottom of his feet. As the subject moves, the orientation sensors detect the movement and send wireless signals to the computer, which translates the raw data into human-like images projected onto a large screen. This provides point data so that the computer model always moves with those points. The point data can then be transferred to animation software.
BENEFITS: The ShapeWrap II is the most portable and affordable of the available motion-capture systems; it can be used anywhere sing a laptop conditions, and costs about ten times less than top-of-the-line optical systems used in Hollywood films. However, one foot must always be planted firmly on the ground, so the subject's "digital double" remains "gravity-oriented" in space.
UNDER PRESSURE: A sensor is a type of transducer: something that receives a signal in the form of one type of energy and converts it to a signal in another from. There are many different kinds of sensors, but most are electrical or electronic. Pressure sensors date back to the birth of the steam engine. Sensors are still used daily to monitor the pressure of fluids in pipes, engines, hydraulics, or to determine, for example, the depth of an ice pack or the density of a rock layer. Sensors use a phenomenon known as piezoresistance: pressure causes a piezoelectric material, like quartz or ceramic, to conduct electricity; the intensity of the current corresponds to how much pressure is being applied. (This is something like the difference felt by your nerves between a soft touch and a pinch.) The charge is detected and recorded by a computer and displayed for analysis by scientists.