technique
Replacement animation
Capture technique
Definition
A technique where expression, mouth shape or body parts are swapped between frames instead of deforming a single continuous object.
Overview
In replacement animation, the animator swaps a pre-built alternative element — a mouth shape, an expression panel, or a limb component — rather than directly deforming the same continuous surface. The technique trades material flexibility for precision: each replacement part is identically engineered and accurately registered, so mouth shapes are consistent across shots and can be reproduced whenever a line recurs in the dialogue.
The technique has a long history in puppet animation. The earliest systematic use was for lip-sync: animators built sets of mouth shapes corresponding to phoneme groups and swapped them frame by frame against the audio track. George Pal's Puppetoons (1941–1947) used carved wooden replacement bodies to achieve fluid character movement before flexible puppet materials were available.
3D printing transformed replacement animation in the 2000s. LAIKA pioneered the use of full-colour 3D-printed resin faces, allowing studios to produce thousands of unique expression panels per film; Missing Link (2019) required approximately 106,000 individual faces. For Wildwood (2026), LAIKA extended 3D printing beyond faces into armature and skeletal fabrication, using printed skeletal forms to achieve more lifelike musculature and performance (Variety, 2025). Faces are registered to the puppet head by precisely machined magnetic mounts that ensure consistent alignment across thousands of swaps.
The choice to use replacement animation is not purely mechanical -- it is a directorial position on how much of the puppet's seams a film should let the audience see. Coraline director Henry Selick has described developing the approach on commercials work (the Pillsbury Doughboy) and deliberately mixing replacement faces with other methods "depending on what kind of role the character has" rather than defaulting to one system throughout a film (BFI Sight and Sound, 2024-08-23). Selick originally wanted Coraline's replacement-face seams left visible, arguing a puppet should still read as "touched by a real person"; the studio's backing was uncomfortable with the visible seam lines, so they were painted out digitally instead -- a choice Selick has since called "an unnecessary expense."