Can an app really judge my dancing?
It can judge the measurable parts — whether a joint reached the angle the reference reached, and whether it got there on time — and it cannot judge the rest: musicality, feel, style, presence. A trustworthy app is one that keeps to the measurable parts, states the error in its own measurement, and refuses to speak when the camera could not see enough. Anything that scores your "energy" or "vibe" from a phone camera is making it up.
What is measurable
Pose estimation gives a position for each joint in each frame. From positions you get angles, and from a sequence of frames you get timing. Both have a margin of error: a few degrees on a big joint in good light, more in poor light or when a limb crosses the body. An honest app treats a difference smaller than that margin as nothing.
Two ways apps go wrong
- Confident guessing: reporting a limb it could not see, or a correction smaller than its own noise. This is the one that sends you to fix things that were fine.
- Scoring the unmeasurable: a single number for a performance, which flatters or discourages without telling you what to change.
The test
Dance a phrase twice, as identically as you can. If the app finds a lot to fix the second time that it did not find the first, it is reporting its own noise. Then dance it with one deliberate error — a late arm — and see whether it finds that one thing and nothing else. That is the whole audition.
Questions people ask
Is a human coach always better?
A coach sees what a camera cannot and knows why you drift. An app is tireless, private and consistent about angles and timing. They are good at different things; a recording is the bridge between them.