Motion Capture or mocap is a term used to describe the process of recorded movement being transferred to a digital model. Such data is used primarily in film, computer games, the military, sports and even in medicine. In film, the term is directly associated with recording the actor's live action and then using the record to revive the model in 3D.
Most advanced mocap applications require hardware devices whose distribution is still limited only to larger companies and research. Though we are not fully aware of it, mocap technology surrounds us every day. It is used in commercials, movies and games without the wider public knowing the actual meaning of this term.
I. The Development of Motion Capture
The technology is experiencing growing popularity thanks to the diversity of its uses. However, it is still clear that nowadays we cannot make use of its potential without proper software and hardware facilities. Nevertheless, if we look into the history of its development we will find that the principles on which mocap operates today were already known in the second half of the 19th century.
Englishman Eadweard Muybridge (1830-1904) became famous as a pioneer of photographic technology, studies of motion, nudes and landscapes. Wider recognition came mainly with his major works Animal Locomotion and The Human Figure in Motion. The initial incentive for his efforts was a bet for $25 000 with the Californian Governor Lelan Stanford over the question of whether or not there is a moment at which a horse at trot does not touch the ground with any of its four legs. Muybridge, whose examination was to confirm or disprove this statement, started a six-year series of photographic experiments in 1872. He eventually confirmed Stanford's estimation that at a certain phase the trotting horse does not touch the ground. This technological trick, which Muybridge invented and applied himself, was based on a series of 24 cameras located along the horse's path and connected to strings stretched across the track. By tearing those strings the trotting horse released the camera's spring-shutters. In 1879 Muybridge invented the zoopraxiscope – a projector with a disc equipped with photographs. When moving, the disc rotated and projected animated images through its lens. This technology is considered to be one of the first cameras in the world. The books Animal Locomotion (1899) and The Human Figures in Motion (1901) are still well sought-after and respected sources of information on the dynamics of the human body. To this day Muybridge is still regarded as the founder of the modern study of human movement.
In 1882 and under the influence of Muybridge, Étienne-Jules Marey (1830–1940) started working on his own photographic technologies which allow the recording of movement (chronophotography). The efforts of the French scientist, physician and physiologist came to fruition with the invention of sphygmograph – a device which graphically records the pulse (sphygmus) and pressure (and is still used in a modified form). Unlike Muybridge, who used several cameras to register him images, Étienne-Jules Marey was able to record 12 images per second on one frame.
In 1931 Harold Edgerton (1903–1990), an important American engineer and a pioneer of high-speed photography, invented an electronic equivalent of the stroboscope, in which he used the intermittent electronic light of the vacuum tube. Previously, as a student of Massachusetts Institute of Technology, he had tried to capture the movement of the rotating engine in his final work. Nevertheless, the stroboscope remains his most important invention. Thanks to this device cyclically moving objects appear in slow motion. In its primary form, the stroboscope is a disc with visors which is located between the observer and the moving object. If the frequency of the flashes is adjusted appropriately to the revolution of the studied object, it appears as in slow motion. Edgerton used flashes of light to photograph fast moving objects. These photographs made him famous throughout the world, as well as his construction of the first in-depth camera and the use of camera flash.
II. Motion Capture and animated film
Rotoscopy is regarded as the immediate predecessor of Motion Capture. It is an animation technique in which the animator redraws previously shot live action (frame by frame) in order to apply it in the animated film. This technique originated as the idea of Max Fleischer who, in 1915, shot his brother David in a clown costume (as the basis for KoKo The Clown). During one year he processed materials into animated form and in 1917 he had the equipment and procedure registered as his patent. A year later he produced the first series of such animations, Out of the Inkwell which combines staged, fictitious scenes in interaction with animated characters. He used this technique for more complex movements of Betty Boop, or in his full-length films Gulliver's Travels (1939), Mr. Bug Goes to Town (1941) etc. Although Fleischer, in his work, focused on comic book characters (Superman, Popeye...), his films (as opposed to the standard production) of the early 30s were full of various gags, gloomy humor and sexual overtones (Betty Boop). After four years of hard work Disney released his feature film Snow White and the Seven Dwarfs in 1937. The success was immediate. It was the first film from Disney's studio made by using rotoscopy. Even though more and more stylized ways of expression began to prevail over time, rotoscopy is still used as a reference material for animators.
From the alternative part of production we can mention the work of Ralph Bakshih who used rotoscopy very often: Wizards (1977), American Pop (1981), and Fire and Ice (1983). Another area of interest for rotoscopy is computer entertainment. Thus some games excelled in their high-class elaboration: Prince of Persia (1989), Another World (1991) and Flashback (1992). At present, this technique is used rather sporadically. It has reached more artistic than animated dimensions. It is applied as a means of expression allowing the viewer to perceive the actor's performance on the brink of feature and animated film (Waltz with Bashir, 2008).
The beginning of the digital technology mocap took place in the 1970s and is connected with the development of modern medicine and new technologies in the army. In the 80s mocap was already known in computer graphics but proper technical hardware and software which would be able to cope with such computationally demanding technologies was still awaited. In 1985, Wavefront introduced the first commercial animation software (even though 3D animation is a matter of only few studios). Thus the first successful attempts began to emerge in the production of animated subtitles and television sections. One of those was a 1985 short spot Brilliance with a digital robot whose movement was pre-played by an actor and transformed afterwards. This method chosen by Robert Abel was based solely on black points located on the actor's body and filmed by cameras. The use of computers for processing such images signified an important milestone.
If we look into the history of film we definitely cannot say that mocap pushed the manual 3D animation out from the area of the third dimension. It is clear that it found its focus in film, especially in the combination of feature film and CGI, that is, in film action closest to reality (The Lord of the Rings, The Mummy, King Kong). The first films to use tricks in combination with Motion Capture were Total Recall (1990) and The Lawnmower Man (1991). When the Film Academy in 2006 had to decide about awarding the Oscar for animated film, the nomination selection consisted of these movies: Monster House, the winner, Happy Feet and the only representative of manual animation, Pixar's Cars. Although we can say that it was one of the weakest years (regarding feature-length films), it was, in its own way, a watershed. It was the last year in which animated films created by using mocap technology were able to compete in the same category. Even though it is problematic for the average viewer to determine the boundaries and nuances, it was then clearly defined what animation is and what it is not.
If we focus on purely animated production it is astonishing how very few feature films using Motion Capture are produced nowadays. The first film created by using mocap was Sinbad: Beyond the Veil of Mists in 2000. With its budget of 30 million dollars it is considered to be the most expensive film for video distribution. Compared to its former competitors it had a lot of artistic shortcomings and soon fell into oblivion. In 2001 the visually attractive Final Fantasy: The Spirit Within appeared. And The Polar Express (2004) with Tom Hanks entered into the general awareness of fairy-tales for children. Monster House was another such film and although it won its authors an Oscar nomination, it still arouses contrasting reactions associated with technological processing. Its visually very successful scenes are disrupted by the impression gained from the characters' movements, which are lacking in exaggeration and therefore look too natural. That concerns also the film's art stylization on which this movement should be based. Concerning the future, we are now facing the question of the significance of using Motion Capture in distinctive art works. In 2007, the Beowulf saga came to cinemas and it proved that it is possible to find such artistic stylization which would sufficiently chime with real movement. There are many challenges awaiting the next generation of films (A Christmas Carol, Avatar) which will be using the mocap technology to the maximum.
One progressive branch of the entertainment industry applying mocap very frequently is that of computer games. In some types of games we find 100% exploitation of mocap (sports, military, combat games), others use it only marginally to simulate walking, running, etc. Two of the first games to use the potential of filming movement were Riste of the Robots in 1994 and FX Fighter in 1995. They represented a more sophisticated type of the traditional "robotic thresher" but with unusually smooth movements. Today, it is rather rare if a studio does not use mocap for its advanced animation. The two largest Czech titles, Arma 2 (Bohemia Interactive) and Mafia 2 (2K Czech) own a Motion Capture studio for their projects.
III. Animation and Motion Capture
Despite the huge potential of Motion Capture it is almost certain that it will not displace manual 3D animation (key-frame). Creators using this technology will have to decide which projects it is suitable for and which ones it is not. With the new technology some studios have rejected their traditional means of processing and moved to faster methods. In practice, however, we encounter a lot of animators who are not inclined towards this movement processing. That is to say that mocap is actually only a technology that records actor's expressions and does not leave much creative space for the animator. He is often limited to basic treatments – the actual framing into a particular environment and the necessary connections of all contacts (hands, fingers) etc. Given that the technology is limited to acting skills the whole topic raises the question of how much we can still talk about animation here...
As already indicated above, this technology has its pros and cons. Mocap requires expensive hardware and special programs for data processing. Some types of Motion Capture may also be challenging regarding requirements for the space in which it is handled. Mistakes caused by actors' performances are usually not detected until the digital processing phase which unfortunately often means a complete re-shoot with the actor. It is also not always easy to transfer the disproportions between the actor and the resultant model. Nevertheless, with respect to all these disadvantages we can still say that with proper project conception the advantages prevail. Mocap is, in the end, much faster than manual animation. Primarily, the director is able to influence the performances of the actors in front of him. The quantity or the length of the recording with its countless variations is not an obstacle; on the contrary, it helps to achieve various acting methods and modifications that contribute to the realization of an appropriate outcome. The simplicity with which you can perform the same scene with different reactions of other actors opens up huge possibilities that can be compared to the theatrical creative process. The main asset, however, lies in the amount of data which mocap enables creators to process in a short time.
— Pavel Hruboš
10 Dec 5:00 p.m. Film Auditorium — MOTION CAPTURE AND ITS INFLUENCE ON THE DEVELOPMENT OF ANIMATED FILM
— lecture – Pavel Hruboš — Motion Capture