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Umpire Signal Scorer: a phone app that scores cricket
A phone app built with Claude in 40 minutes that watches the umpire, reads his arms and suggests the score, but only counts it when you tap confirm.
Umpire Signal Scorer points your phone at a cricket umpire and reads his arms. When he signals a six, a wide or an out, the app suggests the score. Nothing counts until you tap confirm.
It was Day 11. A random wheel picks the app and I get one hour. The wheel picked this one, and it was done in 40 minutes.
How it reads an umpire
Google's free MediaPipe pose model puts 33 points on the umpire's body. That tells the app where his arms are.
Simple rules do the rest. If both his wrists go above his head, it's a six. The rules are measured in his shoulder widths, so the distance between you and him doesn't matter.
The first try read 9 of 26
The first version read only 9 of 26 signals from real umpire videos. Real umpires don't follow the textbook, and that's why the score was so low.
Two examples came up. Umpires hold a wide arm higher. The signal for four is a slow wave. A rule that expects the textbook version misses both.
So I tuned every rule on real umpires. After that the app reads 19 of 26. That still leaves seven signals it gets wrong.
Out and bye look alike
One arm up could mean out, or a bye. The arm alone doesn't settle it, so the app zooms in on his hand.
One finger is out. An open palm is a bye.
Why the confirm tap matters
The app suggests a score and you decide. Nothing scores until you tap confirm, so a stretch can never count as a six.
With 19 of 26 as the hit rate, that tap matters. A wrong read only stays a suggestion unless you confirm it, so the app can't change the score by itself.
The video also stays on your phone.
The umpire footage came from Muhammad Qureshi on YouTube.
What to take from it
If you build something that reads the physical world, test it on real footage early. A first result of 9 of 26 is useful because it shows you which rules to fix. Measure against something on the subject, like shoulder widths, and keep a human confirmation step for anything that changes a score. To get the app, comment UMPIRE on the reel.
