Al writes "Researchers at the MIT Media Lab have created a cheaper way to track physical motion that could prove useful for movie special effects. Normally an actor needs to wear special markers that reflect light with numerous high-speed cameras placed around a specially-lit set. The new system, called Second Skin, instead relies on tiny photosensors embedded in clothes that record movement by picking patterns of infrared light emitted by inexpensive projectors that can be mounted in ceilings or even outdoors. The whole system costs less than $1,000 to build, and the researchers have developed a version that vibrates to guide a person's arm movements. Watch a video of Second Skin in action."