Motion Capture 101
Motion capture technology has been used on some of the biggest films of all time, from James Cameron’s Avatar to Avengers: Endgame - but how exactly does it work?
Motion capture is a process of recording traditionally used in movies, television shows, video games and more, that captures an actor's movements and/or facial expressions, and translates them onto a 3D rendered character.
Motion capture technology has roots in the life science market, where, in the early 1980s, computer scientists and researchers would track patients’ knee flexion and extension. Twenty years later Sinbad: Beyond the Veil of Mists’ became the first feature-length computer animation movie to be created exclusively using motion capture. While the film itself commercially failed (with gross revenue of less than $30,000 worldwide and an estimated budget of $30 million), the technology caught the eye of inventive filmmakers, including Peter Jackson, who would go on to use motion capture in ‘The Lord of the Rings Trilogy’. Since then motion capture technology has been a mainstay throughout big-budget filmmaking and beyond.
How does motion capture technology work?
The process of motion capture is predominantly technology-driven. The first component of recording motion capture is the suit, which is fitted with various sensors.
The actor then performs in the suit, with their actions being recorded by motion-tracking cameras, which turn their movements into data. This data is then sent into motion capture software such as GIANT where a post-production team translates this into a virtual skeleton. As the actor moves, the virtual skeleton then matches their movements on a monitor, allowing the actors and production team to watch and review their movements in real-time.
Once the desired performance is achieved, the post-production team then animates the digital character on top of the virtual skeleton within a program such as MotionBuilder. This allows the team to ‘clean up’ the motion capture data, and refine the movements of the character for the final version.
Benefits of motion capture
Motion capture is often described by actors as ‘digital makeup’. Actors wear motion capture suits, and digital assets are then placed onto their faces or body in post-production. This means that when an actor dons a motion capture suit, all of their exact movements are captured, ensuring that the subtlety and naturalism of a performance can be directly replicated, and embodied, in the digital version of their character.
Filmmakers often find that working with motion capture technology leads to less time spent in post-production. A performance captured using motion capture is close to real-time, with most modern studios now working with high capability, low-latency software. The amount of time and money spent filming with motion capture, compared to the costs of traditional animation, means that directors and actors can spend more time on their craft.
What is motion capture used for?
It’s a common misconception that motion capture is solely used on big-budget Hollywood productions. Over twenty years from the inception of motion capture’s use in films, mocap technology is increasingly accessible and studios of all sizes are implementing motion capture, with independent productions such as District 9 receiving critical acclaim for their use of the technology.
Story-based video games such as The Last of Us and Gears of War are often equal to Hollywood productions in their emotional depth and quality. As character development became increasingly pivotal to games’ plots, acting within video games grew in its importance and, with that, so did the industry’s adoption of motion capture technology. Audiences demand the same quality in the performances of a video game - especially in the cutscenes - as they would a film, and game developers’ use of Unreal Engine is now inspiring the film industry.
Motion capture is also being implemented throughout Web 3 and metaverse adjacent projects, as creators in that space look for new ways to immerse their audiences into virtual worlds. Beyond the world of entertainment, motion capture is also being used by healthcare, military, sport, farming, and many more industries worldwide.
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