Scenario Blender Previs Storyboard

Previs, layout and storyboarding

Expert previs conveys an idea well enough to be judged, as cheaply as possible: one fact per beat, every shot designed for what the audience must feel, timing found in the edit from stills. The camera is the audience's body; where it stands, how high and through which lens decides the emotion, so every non-neutral choice needs a stated reason. If a sibling skill named here is missing from your available skills, ask the user to install it (npx skills add scenario-labs/skills --skill <name>); unattended, proceed from tool schemas and flag the gap.

REQUIRED BACKGROUND: scenario-blender-expert (execution channel, review loop, 5.2 API changes).

Toolkit: scripts/bx_previs.py (tested on 5.2.1): import sys; sys.path += ["<this skill>/scripts", "<scenario-blender-expert>/scripts"]; import bx_previs as P.

Which skill. This one: story previs and animatics judged by a director and an editor. text-image-to-blender-blockout instead when the playblast guides a render-to-real video model (Seedance): saturated color identities, no lens jump on a cut, eased moves, a hand-off sheet; an approved animatic that must become a video guide is rebuilt there. Shared: metric Z-up, roots at the feet, one camera per shot bound to a marker, to_track_quat('-Z','Y') look-at. Strokes: scenario-blender-grease-pencil. Animation after layout: scenario-blender-animation. Real rigs: scenario-blender-rigging.

Stance (the expert delta)

• Hjalti Hjalmarsson: write the beats-of-information list before any shot. One fact per line, because a viewer takes in one thing at a time. Group consecutive beats into shots; a new treatment re-orders the same facts. A missing beat means the idea never gets a fair test.
• Hjalti: theater first, then cinematic; shots cost time. A locked-off version judges the acting; the same beats told in shots ran about 2x (up to 3x) because every cut must be read (13/22/25 s vs 47/40 s). The oversimplified version is always too short and hides logistics (a character cannot cross the room in 10 frames).
• Charge recipe (Hjalti): treat every frame as a storyboard drawing. 10 frames per shot, keys CONSTANT, an A/B alternative on the next frame, the winner on the decade frame, stills exported with versioned names, timing done in a separate edit.
• Hjalti: when in doubt, eye height; lock the lens early by A/B. Two characters: split their eye heights. Low or high is a statement. Poses built for one lens do not survive a lens change.
• Dillon Gu: composition and focal length are separate decisions, and cuts can kill a mood. The audience stands where the camera is. Leaving the space removes the danger; two inanimate inserts in a row lower tension.
• Cheat for the camera, but key before you cheat (Hjalti, Charge, Renato Roldan). Resize, float, swap props per shot; in a shared timeline an unkeyed cheat breaks the earlier shots.
• Previs is the cheapest version that still conveys the idea (Hjalti, Charge). Animate only shots whose camera move is the storytelling; everything else is one still, push-ins faked on the still in the edit. Grays in Workbench, no mood lighting, mannequins before rigs. P.audit refuses a camera moving inside a still shot, keys between block starts and a non-Workbench engine.
• After each cut the eye must find one thing (Hjalti). Restage a character in front of a competing subject; keep the angle that preserves the emotion (he refused a side cut that turned Rex into a silhouette).

Establish first

Workflow

1. Script to beats. Asset list, then numbered beats, one fact each; mark every beat you add. GATE: P.shot_list(BEATS, SHOTS) raises on a missing, duplicated or reordered beat.
2. Set and proxies. P.setup_scene (format, Workbench, grays, Standard view transform); P.prop for real-scale set pieces; P.mannequin for characters (root at the feet with eye_height, four pivot controls as the layout subset). Grays, one pop color for the hero (Renato: red). GATE: scale reads next to a door (2.1 m) and counter (1.0 m).
3. Theater pass. One locked-off camera (cam shared, fit="all", 35 mm, mean eye height) framing the action's extremes; one block per beat group. GATE: in the P.audit rows every subject's head_in and feet_in is true at every block; theater edit timed.
4. Cinematic plan. List several openings, re-order beats, group them into shots with intent, size, lens, height, dur. P.floor_plan with the action line and journey paths before judging cameras. GATE: one side of the line; journeys follow the direction rule.
5. Blocking. For each block: sc.frame_set(f) (holds the previous pose), set only what changes, P.key_block(all_movables, f); cheats go through the same keys; then P.make_stepped. GATE: P.stepped_report == {}; the cheat check at neighboring shots.
6. Cameras. P.build_shots places each camera from size, lens and eye height (or explicit loc/aim), sets an opaque passepartout (Charge: see only the composition; P.passepartout(sc) for other cameras) and binds a marker at its first frame. P.ab_lens on key shots before posing further. GATE: P.audit(...)["problems"] == [].
7. Look. P.contact_sheet and open it. Characters merging with a dim set: P.fog_for_shot(sc, t, chars) (Hjalti: depth fog for readability, not lighting; behind the subjects, keyed to that shot), P.values_at hero vs backdrop. GATE: the visual list under Quality gates (in S6 only the pictures caught the occlusions and the cut-off wide).
8. Edit. P.render_stills, then P.animatic (image strips held dur seconds, push on stills, live shots as scene strips, sounds, burn_in). One continuous action from several angles (Pablo, Story Tools): a live shot plus cover=True shots become one scene strip soft-split per camera; retime with P.retime_cut (the marker follows), never by moving keys. GATE: runtime within budget; frames pulled from the MP4 match the cut list.
9. Iterate in a new scene pair (02_blend/02_edit) and new version numbers; nothing overwritten.

Numbers