Motion capture, motion tracking, or mocap are terms used to describe the process of recording movement and translating that movement on to a digital model. It is used inmilitary, entertainment, sports, and medical applications, and for validation of computer vision and robotics. In filmmaking, it refers to recording actions of human actors, and using thatinformation to animate digital character models in 2D or 3D computer animation. When it includes face and fingers or captures subtle expressions, it is often referred to as performance capture.In motion capture sessions, movements of one or more actors are sampled many times per second, although with most techniques (recent developments from Weta use images for 2D motion capture andproject into 3D), motion capture records only the movements of the actor, not his or her visual appearance. This animation data is mapped to a 3D model so that the model performs the sameactions as the actor. This is comparable to the older technique of rotoscope, such as the 1978 The Lord of the Rings animated film where the motion of an actor was filmed, then the film used as aguide for the frame-by-frame motion of a hand-drawn animated character.
Camera movements can also be motion captured so that a virtual camera in the scene will pan, tilt, or dolly around thestage driven by a camera operator while the actor is performing, and the motion capture system can capture the camera and props as well as the actor's performance. This allows thecomputer-generated characters, images and sets to have the same perspective as the video images from the camera. A computer processes the data and displays the movements of the actor, providing thedesired camera positions in terms of objects in the set. Retroactively obtaining camera movement data from the captured footage is known as match moving or camera tracking.