Gears of War: Motion Capture Session

Motion capture, motion tracking, or mocap are terms used to describe the process of recording movement and translating that movement onto a digital model. It is used in military, entertainment, sports, and medical applications. In filmmaking it refers to recording actions of human actors, and using that information to animate digital character models in 2D or 3D computer animation. When it includes face, fingers and 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 ILM use images for 2D motion capture and project into 3D) motion capture records only the movements of the actor, not his/her visual appearance. This animation data is mapped to a 3D model so that the model performs the same actions 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 visual appearance of the motion of an actor was filmed, then the film used as a guide 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 the stage 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 the computer 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 the desired 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.

Video games often use motion capture to animate athletes, martial artists, and other in-game characters. This has been done since the Atari Jaguar CD-based game Highlander: The Last of the MacLeods, released in 1995.

Movies use motion capture for CG effects, in some cases replacing traditional cel animation, and for completely computer-generated creatures, such as Jar Jar Binks, Gollum, The Mummy, King Kong, and the Na'vi from the film Avatar.

Sinbad: Beyond the Veil of Mists was the first movie made primarily with motion capture, although many character animators also worked on the film.

In producing entire feature films with computer animation, the industry is currently split between studios that use motion capture, and studios that do not. Out of the three nominees for the 2006 Academy Award for Best Animated Feature, two of the nominees (Monster House and the winner Happy Feet) used motion capture, and only Disney·Pixar's Cars was animated without motion capture. In the ending credits of Pixar's film Ratatouille, a stamp appears labelling the film as "100% Pure Animation -- No Motion Capture!"

Motion capture has begun to be used extensively to produce films which attempt to simulate or approximate the look of live-action cinema, with nearly photorealistic digital character models. The Polar Express used motion capture to allow Tom Hanks to perform as several distinct digital characters (in which he also provided the voices). The 2007 adaptation of the saga Beowulf animated digital characters whose appearances were based in part on the actors who provided their motions and voices. James Cameron's Avatar used this technique to create the alien characters. The Walt Disney Company has announced that it will distribute Robert Zemeckis's A Christmas Carol and Tim Burton's Alice in Wonderland using this technique. Disney has also acquired Zemeckis' ImageMovers Digital that produces motion capture films.

Television series produced entirely with motion capture animation include Laflaque in Canada, Sprookjesboom and Cafe de Wereld in The Netherlands, and Headcases in the UK.

Virtual Reality and Augmented Reality allow users to interact with digital content in real-time. This can be useful for training simulations, visual perception tests, or performing a virtual walk-throughs in a 3D environment. Motion capture technology is frequently used in digital puppetry systems to drive computer generated characters in real-time.

Gait analysis is the major application of motion capture in clinical medicine. Techniques allow clinicians to evaluate human motion across several biometric factors, often while streaming this information live into analytical software.

Motion tracking or motion capture started as a photogrammetric analysis tool in biomechanics research in the 1970s and 1980s, and expanded into education, training, sports and recently computer animation for television, cinema and video games as the technology matured. A performer wears markers near each joint to identify the motion by the positions or angles between the markers. Acoustic, inertial, LED, magnetic or reflective markers, or combinations of any of these, are tracked, optimally at least two times the frequency rate of the desired motion, to submillimeter positions.