Character consistency across shots.

Why a character drifts

A generated frame starts from a description, and a description underdetermines a person. "A woman in her thirties, dark hair, a grey wool coat" is true of millions of faces, and the engine resolves the ambiguity afresh on every call. Change one word of the prompt, or the shot size, or the light, and the resolution lands somewhere else. Frame by frame the results are all plausible. It is only when they are cut together that the audience sees a stranger in every other shot.

The problem compounds across a production in a way it does not across a single image. A still is judged alone; a sequence is judged against itself. Wardrobe drifts as easily as faces — the buttons, the collar, the exact grey. Locations drift: a window appears, the table changes shape. Even a graded look drifts, so the warm interior of scene four is cooler in scene five for no reason anyone chose. Each is small. Together they are the difference between a film and a folder of pictures, and they are the reason a producer who has been shown a beautiful generated frame is right to ask what the next one will look like.

What the usual fixes do, and where each stops

Describe the character the same way every time. Keep a canonical paragraph and paste it into every prompt. This helps at the margin and fails at the centre: it narrows the ambiguity without removing it, and the paragraph is a thing held by hand, so by shot thirty somebody has shortened it.

A character reference sheet. A turnaround of the character — front, three-quarter, profile, a close-up — made once and attached to every generation as a reference. This is the right idea, and it is where most workflows stop. Its limit is that nothing checks the result. The reference is offered to the engine; whether the engine honoured it is left to a person squinting at thumbnails. And a sheet is a face. It is not the coat, not the kitchen, not the grade.

A trained model of the character. Fine-tuning an engine on many images of one person. Strong when it works, costly to set up, tied to one engine, and silent about what to do when the production routes a shot to a different engine for a different reason. It also answers only the face question. A production has a dozen identities to hold at once.

Fix it in the edit. Re-generate until it matches, or retouch. This is the honest description of what most teams actually do, and it is where the cost of generation stops being low: every retry of a drifting shot is paid for again, and the retries are not counted anywhere.

A lock: decide once, apply everywhere, measure every time

The durable answer treats continuity as a decision with three parts rather than a prompting habit. Decide once. A locked identity is made from a reference — one image can be enough, with the turnaround derived from it — and named: this is Mara, this is her coat in the rain scene, this is the kitchen. A lock is scoped where it should be, so the wedding coat and the rain coat are two locks on one character, and continuity is held per scene rather than flattened across the film.

Apply everywhere. The lock is attached to every generation in every room — the storyboard frame, the signed keyframe, the staged scene, the moving take — automatically, without a person remembering to paste anything. A render made under the lock carries that fact in its record, so later the question "what was this made from?" has an answer.

Measure every time. Every locked render is scored against its reference on identity, styling and palette and marked pass, warn or fail, on the board where the frame sits. A warning means look. A failure means the frame does not go forward. Across a project the pass-rate is one number — the Continuity Index — that says how well the whole production is holding, and a producer can read it before a client does. This is a measurement, and it is worth being precise about what that means: it catches drift so a person can act; it does not promise that no frame will ever need a second look.

The last piece is what happens when a decision changes. The lead is recast; the coat becomes blue. In PREVIZ a lock is versioned, and every frame, take and set made under the old version is marked stale, in every room, the moment the lock moves. The alternative — finding those frames by eye across six rooms — is how a board ships with half its shots belonging to last week's cast.

Where PREVIZ does it

The Continuity Lock is the capability; it is not a room but the thing under all six. Locks are made in Keyframe, the room where a production signs the frame everything downstream inherits, and from a single reference where that is all there is. Every rendering room — Storyboard, Keyframe, CineForge, Director, and the Infinitum board — generates under the locks and scores the result; the drift check is the grading pass and the Continuity Index is its aggregate. A record of every frame's references and parents is kept on the canvas, and it is what the production package's cast and continuity sheet is built from.

What the lock does not do is replace judgement about performance, which is a different thing from identity and belongs to the director; and it does not hold continuity for work made outside the platform. The script to storyboard page shows the lock applied through a board; the workflow overview puts it among the three connectors that hold the six stages together. Every plan has it, and plans differ by credits alone.

Questions people ask