Scale Zoom Explainer — our demo

One example among many. Don't reuse its story, arc, shots, props or timings.

Demo: The Long Way Down 《一路往下縮》 (52.0 s) · flat-space-explainer.mp4 · source in demo/

A little probe whose eye is a zoom lens takes us from the Milky Way down to a virus, six levels, one comparison per level. English narration, bilingual subtitles (Chinese line above, English line below); on-screen text in English with one Chinese line under the title.

Story & structure

Logline: Orbi fires a dotted sight line at each next stop and dives through it; on your fingertip it is shown at its true size for the first time, then shrinks with us until it is the size of a virus.

Arc: the hook (a full-frame lens blinks and focuses; pull back to find who and where) → the galaxy (title, the first sight line locks on the Sun) → the Solar System (sunlight walks to Earth in dots, a clock runs to 8:20) → Earth (orbits at true scale, a tape measure, Earth as a basketball, a magnifier on the Space Station) → your hand (through the clouds onto a fingertip; the camera pulls back: Orbi is 2 cm, the size of a grape) → your blood (through the skin; a white blood cell turns to Orbi, Orbi jumps, the cell eats a bacterium instead) → a virus (into Orbi's own lens; Orbi sits on the virus and looks back) → the summary (the virus shrinks into the last stop of the scale ribbon, dots run from galaxy to virus, the ribbon fills, Orbi winks).

Orbi's size runs as one thread in the narration: drawn big so you can see it → its true size on your hand → it shrinks with us → now virus-sized.

Native moves spent: the sight line six times, each going further (aim, light, tape, aim at the skin, aim at the virus, the ribbon); through the ring into the Solar System; true size, at last on the hand; inside the lens for the virus; the scale ribbon summary at the end. Other transitions: a shape match (Earth's dot becomes Earth), clouds, concentric skin layers.

Shots

Times in seconds on one timeline.

# Time Shot Camera Native move / note
1 0–1.25 full-frame lens: a glance, a blink, the barrel steps out to focus extreme close-up, slight push the hook
2 1.25–2.9 Orbi appears whole, the galaxy slides in from the right log pull-back from rest, 2 % overshoot three parallax layers
3 2.5–4.8 the title rises word by word; the scale ribbon draws on, the readout rolls to 185,000 light-years locked Orbi nods as each word lands
4 4.4–7.5 wind-up (squash, back, panels swept) → barrel out → recoil, the sight line fires at the Sun slow push sight line 1
5 7.3–10 the ring locks on the Sun; Orbi's iris widens, it smiles, hops, blinks push toward the ring next-stop ring
6 10–12 the ring fills the frame, the galaxy blows past, the Solar System grows inside it; the title drops out accelerating push through the ring
7 12–16.2 the Sun at true size is a dot; sunlight walks to Earth in dots; a clock 0:00 → 8:20 tracking the light while pulling out sight line 2 (light)
8 16.2–17 Earth's dot grows into a disc fast push shape match
9 17–25.9 Earth and three orbits at true scale; a tape from the geostationary orbit to the ground; basketball seams on Earth; a magnifier on the Space Station: 400 km, "< 1 cm" on a basketball settle, locked, inset sight line 3 (tape); frame within frame
10 25.9–27.3 tape reeled in; a fall toward "You", cloud banks rush past accelerating push + fly-through the cut hides behind the thickest bank
11 26.9–30.2 a blue sky; Orbi lands on a pointing fingertip (close-up), then the pull-back shows the whole hand follow the fall → wide pull-back true size, at last
12 30.2–33.6 a "2 cm" bracket and a 2 cm grape side by side, held 30.5–33.0; Orbi looks at itself and smiles; a short sight line to the skin locked sight line 4
13 33.1–35 push into the fingertip; skin layers open as circles fast push + concentric iris
14 35–40.9 red blood cells drift; a white blood cell chases a bacterium, turns to Orbi (Orbi jumps), then swallows the bacterium slow push sight line 5 finds a 0.1 µm virus
15 40.9–42.2 the camera dives into Orbi's lens; the virus is inside the glass subjective push inside the lens; near-silence
16 42.2–45.8 a virus, 0.1 µm; the edge of one hair fills the right side (80 µm wide); Orbi lands on the virus and looks back slow push
17 45.8–52 the virus shrinks into the ribbon's last stop; "28 powers of ten"; dots run through the six stops, the ribbon fills; Orbi hops and winks; end card from 49.1 gather, locked sight line 6; ribbon summary

Narration and subtitles

Kokoro af_heart (a warm, unhurried teacher), speeds 0.68–0.86, about 2.3–2.8 words per second. Every line passes asr_check.py (the asr fields in demo/vo/lines.json hold what the model hears for "Orbi" and a few spellings).

Id Time English (voice) Chinese (subtitle)
v1 2.4 This is our galaxy. A hundred thousand light-years across. 這是我們的銀河系，寬約十萬光年。
v3 12.2 The Sun's light takes more than eight minutes to reach the Earth. 太陽的光，要走八分多鐘才到地球。
v4a 17.6 Shrink the Earth to a basketball, 把地球縮成一個籃球，
v4b 20.6 and the Space Station flies less than a centimetre above it. 空間站離它的表面還不到一釐米。
v5a 26.9 We drew Orbi big, so you could see it. 前面為了讓你看清，Orbi 一直畫得很大。
v5b 30.6 This is its true size: about one grape. 這才是它真實的大小：一顆葡萄那麼大。
v6a 34.45 Now Orbi shrinks with us, into your blood. 接下來，Orbi 跟著我們一起縮小，鑽進你的血裡。
v6b 38.7 Some cells here hunt. 這裡有些細胞，會捕獵。
v7 41.05 Now Orbi is virus-sized: a thousand times thinner than a hair. 現在 Orbi 和病毒一樣小：比一根頭髮細大約一千倍。
v8 46.04 From galaxy to virus: ten times smaller, twenty-eight times over. 從銀河到病毒，每次縮小十倍，一共縮了二十八次。

Numbers are spelled out in the voice text and written as digits in the subtitles. Each cue holds max(1.8 s, speech + 0.6 s); the shortest is 2.32 s.

Score structure

96 BPM, a bar = 2.5 s, 21 bars; D major, D minor inside the body.

Section Time Palette Notes
Galaxy 0–10 bowed vibraphone fifth; harp sweep up on the pull-back; pizzicato double bass, vibraphone Dmaj9, a pizzicato note per title word, xylophone run with the readout; shaker 16ths the wind-up half-beat is silent; the lock: glockenspiel, triangle, timpani; an unresolved A sus4
Dive 10–12 harp falling, suspended cymbal crescendo, timpani on arrival
Solar System 12–17 bowed vibraphone Lydian pad; one glockenspiel note per step of the light, rising hand chimes + triangle when the light lands
Earth 17–25.9 marimba walking 8ths, pizzicato bass, light shaker glockenspiel accents on the seams and the inset
Clouds 25.9–27.3 the music thins: cymbal swell, harp falling
Hand 27.6–33.6 nylon guitar arpeggios in G vibraphone chord + three harp notes on "true size"
Blood 33.6–40.9 heartbeat; pizzicato cellos in D minor, a low bowed double bass violin tremolo + timpani on "hunt", a falling xylophone flourish when Orbi jumps
Lens 40.9–42.2 glass harp rising, then near-silence under the voice
Virus 42.2–45.8 hand chimes, sparse glockenspiel, a high bowed pad
Finale 45.8–52 everything back; one glockenspiel note per stop, rising; harp run as the ribbon fills; D major tutti at 49.15 a bowed pad and two bells let it ring out to 52 s

Mix (in mix.py): voice compressed, music ducked ~10 dB under the voice and dipped 300 Hz–4 kHz; foley from the page's events (window.EV): servo whirrs, blink clicks, dot blips, ring locks, whooshes, a thruster bed, a basketball bounce, a gulp. −14 LUFS, true peak −1.1 dB.

Palette & props

End card

From 49.1 s, bottom right of the final ribbon shot, wiped in line by line and held to the end (2.5 s fully written): THE LONG WAY DOWN · 一路往下縮, Scale Zoom Explainer · 扁平尺度漫遊, LemoLab × Claude Opus 5.5 in sun yellow. The "LemoLab × Claude Opus 5.5" sign-off belongs to this library's demo only; a user's film carries no LemoLab credit and no copy of this card.

Build notes

demo/
  build.sh       one command: fonts (if missing) → voice (if missing) + asr_check → events → video → mix → master → .srt → readcheck → poster
  index.html     the page; ?f=1|2|3|options draws the three style frames and the character sheet, no ?f draws the film
  flat.js        palette and flat-drawing helpers
  orbi.js        Orbi with continuous pose parameters (the film)
  heroes.js      the guide, Orbi, as drawn in the style frames and the character sheet
  sheet.js       the guide's character sheet (?f=options)
  film.js        0–10 s: camera and parallax, Orbi's first performance, title, first sight line, next-stop ring
  scenes.js      10–52 s: every later level and transition, scale ribbon, subtitles, end card, sound events
  mix.py         narration placement, score, foley, mix → out/mix.wav and out/cues.json
  shoot.mjs      the style frames as PNGs
  vo/            lines.json (voice text, speeds, asr fields), dur.json; the clips are local
  tools/fonts.py fetch Jost and the Noto Sans SC subset
  FACTS.md, CREDITS, stills/styleframe.jpg