motion capture (mo-cap)

Motion capture (mo-cap) is the use of sensors on real bodies (objects and beings) to track motion and record the movements digitally, typically for transferring to virtual 3D imaging.

Mo-cap is used for various applications including the creation of animation, video games and movies. It can also be used for creating simulations for training or engineering purposes. In real time, the sensors used with virtual reality (VR) setups capture motion and allow it to be transferred from a player. Mo-cap can record the actions of a master in a physical field for uses in entertainment or training purposes for learners.

Mo-cap tracks numerous points on a body. These points are often at the tips of extremities and at joints. Typically, each point has a marker or an emitter that is tracked by a sensor or an array of sensors. As an actor or actors go through a complicated sequence, such as two individuals sword fighting, the motion of the tracked points is recorded as translations through an XYZ-coordinate space, with varying degrees of accuracy. This data generally has to be cleaned up as some small errors in tracking may make for some unnatural movements, but it is much easier and less time-consuming than hand animating overall.

Rotoscoping, a precursor to mo-cap, was used in many animated TV shows and movies. In rotoscopy, a sequence is captured in video and characters are drawn over top of the actors to facilitate the creation of realistic animation. Rotoscoping is frequently used as a technique for combining (compositing) cartoon figures with realistic settings in television commercials and is also used for special effects in feature-length films.