From da0567b79d36f499588bd3ea783b0c960041d3ef Mon Sep 17 00:00:00 2001 From: Jeremy Kashkett Date: Thu, 16 Jul 2026 13:48:10 -0700 Subject: [PATCH] docs(dances): dance1 motion description from Blender kinematic analysis Co-Authored-By: Claude Fable 5 --- docs/dances/dance1.md | 58 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 docs/dances/dance1.md diff --git a/docs/dances/dance1.md b/docs/dances/dance1.md new file mode 100644 index 0000000..34f0f9a --- /dev/null +++ b/docs/dances/dance1.md @@ -0,0 +1,58 @@ +# dance1 — motion description + +Kinematic description of the `dance1` clip (`dancegen/dance1.glb`, clip `Dance1`), +derived by sampling world-space bone positions across the whole clip in Blender — +not a subjective guess. Duration **30.0 s**, retargeted onto the Quaternius rig. + +## One-line read +An energetic, **arm-forward** full-body dance: big symmetric sweeping arm gestures +carry the performance, over busy footwork and pronounced level changes, while the +whole body ranges around a ~1.2 × 1.7 m footprint. It never settles — continuous, +flowing motion for the full 30 seconds. + +## What actually moves (path length over 30 s = how much a joint travels) + +| Rank | Body part | Travel | Read | +|---|---|---|---| +| 1 | **Both hands** | ~49–50 m each | The stars of the dance — huge, near-constant sweeps | +| 2 | Forearms | ~32–33 m | Big arcs from the elbow reinforce the hand work | +| 3 | Shins | ~25–26 m | Busy legs — steps, lifts, direction changes | +| 4 | Upper arms / feet | ~18–21 m | Full-shoulder arm swings; active but grounded feet | +| 5 | Head / spine / pelvis | ~16–17 m | Whole torso rides along — leans and level changes, not stiff | + +Hands move at roughly **1.7 m/s average** with constant direction changes, and each +hand's reach spans ~1.7–2.5 m per axis — meaning full-wingspan sweeps that go both +**high** (≈1.5–1.7 m vertical range) and **wide**. This is expansive, expressive +upper-body choreography, not tight or contained. + +## Character traits +- **Highly symmetric arms** — left/right hand travel matches at a **0.99 ratio**. The + arm choreography is mirrored/synchronized, the hallmark of a choreographed or + group-style routine (consistent with Polynesian dance vocabulary). +- **Slight left-foot bias** — feet symmetry is 0.89 (left foot a bit busier), so the + legwork isn't perfectly mirrored; there's a lead side. +- **Big level changes** — pelvis vertical range is **0.94 m**. The dancer drops and + rises a lot (deep bends / crouches into extensions), which gives the dance its + dynamic, punchy feel rather than staying at one height. +- **Travels the space** — pelvis moves over a **1.2 × 1.7 m** horizontal area (16 m of + total travel), so it's not planted-in-place; expect stepping and repositioning. + +## Rhythm / tempo (caveat) +Autocorrelation of the most-active joint's vertical motion peaks around **~205 bpm**, +which is almost certainly the **double-time harmonic** of the real musical pulse — +halving it gives **~100–103 bpm**, a lively mid-tempo. Treat this as approximate: the +trustworthy tempo comes from the **source reference video's** music, not the retargeted +motion. The `bpm: 100` in `dance1.json` is a hand-set placeholder that happens to land +in the same neighborhood. + +## If scoring a song to it +Aim for a **~100 bpm** groove with a strong backbeat and room for **sweeping, +sustained phrases** (to match the long arm arcs) punctuated by **accents on the level +drops** (the pelvis dips). Symmetric, repeating 4- or 8-bar structures will sit well +against the mirrored, cyclic choreography. Confirm the real tempo against the source +footage before locking it in. + +--- +*Generated 2026-07-15 from `exchange/converted-glb/dance1.glb` via Blender headless +motion sampling. Method: per-frame world-space bone positions → path length, bounding +range, L/R symmetry, and vertical-signal autocorrelation for tempo.*