Typical Motion Capture Camera

They act as highly precise video cameras tuned to see within the infrared portion of the energy spectrum rather than within the range of visible light.

The tripod-mounted cameras are pointed towards the center of the lab, where the subject will walk or perform an action.

A band of infrared light-emitting diodes surrounding an optical lens on each camera bathes the center of the lab with invisible infrared light. This light reflects off the reflective markers placed on the subject and bounces back into the lenses of the cameras.

The data-collection computer connecting all the cameras determines the precise position in three-dimensional space of each of the reflective markers dozens of times each second as the subject moves within the lab.

By later examining the recorded data and analyzing the positions of the markers while knowing their exact placement on the subject's body, we can determine how the subject walked.