# 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.*