technique
Model animation
Stop motion
Definition
A sub-type of stop motion in which a rigid-armature miniature figure -- typically a creature or effects subject rather than a soft-bodied character puppet -- is frame-animated and composited into live-action footage, most closely associated with Willis O'Brien and Ray Harryhausen. In its strict, effects-lineage sense the term is defined by that live-action integration; in wider industry usage, especially in Britain, "model animation" also serves as a general label for character stop-motion craft across effects and puppet-only production alike.
Overview
Model animation names the practice, developed by Willis O'Brien on The Lost World (1925) and King Kong (1933) and refined by his protege Ray Harryhausen from Mighty Joe Young (1949) onward, of frame-by-frame animating a jointed miniature figure so that the finished shot reads as one continuous space with photographed actors and sets. Harryhausen drew a deliberate line between this and "puppet animation": in his own account, a model-animated creature is built to disappear into a live-action world and stop calling attention to itself as animation, where a puppet-animation film -- entirely constructed, frame by frame, with no live-action plate to match -- is animation as the whole visual medium, not a component folded into it. Getting a model to hold that illusion drove the technique's two hallmark constraints: an internal metal armature precise enough to take a held pose under repeated single-frame exposures without drifting, and a compositing pipeline -- rear projection, then Harryhausen's own split-screen and matte process he branded Dynamation -- built to register the miniature against a live-action plate shot separately.
Harryhausen and historian Tony Dalton's book A Century of Model Animation: From Melies to Aardman (Aurum Press, 2008) traces the lineage this term covers: it opens with Melies' trick photography, gives Willis O'Brien and Harryhausen's own effects-integration work its central chapters, and closes with Aardman -- a studio whose Wallace & Gromit and Chicken Run productions are pure puppet animation with no live-action plate at all. That range is the honest state of the term: Harryhausen's own working distinction (model animation = live-action integration; puppet animation = self-contained animated film) coexists with a looser, more common industry and British usage in which "model animation" is simply the general name for character-driven stop-motion craft, effects work and puppet-only films alike. This database treats model animation as the specific, live-action-integrated sub-type and cross-references puppet-animation and dynamation for the related and overlapping usages.
The distinction matters for how a shot is planned, not just what the finished frame looks like. A puppet-animation shot only has to be internally consistent -- lighting, scale and camera move are all built inside the same miniature stage. A model-animation shot has to match a live-action plate that was often filmed first, on a different set, months apart: the miniature's lighting direction, lens perspective and any camera move have to be reverse-engineered to fit a plate the animator cannot re-shoot. That matching problem -- not the armature or the material -- is what the term is really naming.