Body-mounted markers capture actor performance and transfer motion to digital character — Avatar, Gollum, performance animation. Real-time tracking feeds skeleton rig with precise joint data.
You're sitting in the motion capture studio — four to eight cameras all around, reflective markers everywhere on the suit and joints. The actor moves, the cameras triangulate each marker in 3D space, 120 to 240 frames per second. Real-time or offline — depending on whether the VFX supervisors need live feedback or if the animator will work with the raw data at their leisure later. The skeleton is calculated, constraints are set, then the motion can be transferred to any avatar. Gollum, Na'vi, the Hulk — all emerge from this data chain: Actor Performance → Digital Structure.
In practice, you need discipline. Some actors forget they aren't visible — they play for markers, not for the camera. You have to give them the space to deliver a full emotional performance, even if the studio is empty all around them. The markers themselves are critical: too few, and you lose finger nuances or spinal rotation. Too many, and the software crashes or miscalculates in real-time. The sweet spot is usually between 40 and 70 markers, depending on project requirements. Facial capture requires extra setup — a frontal rig with densely packed markers on the face, or nowadays even LED dots under the skin when dealing with micro-expressions.
The data itself is brutal: millions of float values per take. Cleanup is 60 percent of the work — identifying marker swaps, interpolating missing frames, filtering noise. No studio can get by without someone who understands this. The motion designer doesn't just sit around and export. They debug, smooth, and correct the skeleton mapping when the computer has confused knees with elbows. Only then does it go to the animation supervisor, who decides which takes are usable and which need to go back to the studio.
Important: Performance Capture and Motion Capture are not the same. Motion Capture is only about movement. With Performance Capture (see also: Facial Performance Capture), you capture facial expressions, eyes, emotions — that's a different beast. And then there are hybrid approaches: live-action shooting with a marker suit, green screen, or digital sets. The actor sees their avatar in real-time on a monitor — sometimes motivating, sometimes completely confusing for the performance.