Show HN：用网络摄像头和姿态模型打造的本地优先坐姿矫正器
Show HN: A local-first posture trainer using your webcam and a pose model
一款本地优先的坐姿训练器在浏览器内运行姿态模型，从网络摄像头每秒取一帧识别 33 个身体关键点，测算头部前伸、肩线倾斜和头部侧倾三个角度，超标即发出提示音。所有计算和读数都留在设备本地，无需密钥、无配额、不上传图像，默认每秒检测一次，最快可调至每两分钟一次。单张快照精度有限，页面以每日柱状条和长期曲线呈现趋势，单帧读数保留两天、每日汇总永久保存，并对比最近 7 天与前 7 天。
This page takes one picture from your webcam every second and reads three angles off it: how far your head sits in front of your shoulders, how far your shoulder line is off level, and how far your head is tilted sideways. The first one matters most - a neck carried too far forward is the reason this page exists. If any of them goes past your limit, it makes a noise, on every single crooked reading. The computing happens here in the browser: a pose model finds 33 points on your body and the page works out the angles itself. No key, no quota, and no picture leaving this device - the readings stay in this browser too.
1 · Start it
Allow the camera and leave the page open. There is nothing to set up and nothing to calibrate: all three angles are ratios measured on your own body, so they do not depend on how tall you are and read the same for anyone. The page measures from the very first frame and keeps the screen awake while it checks.
2 · Pick the pace
One picture a second by default, stretchable to two minutes. Because everything is computed locally, a fast pace costs nothing but a little battery - there are no requests to count.
3 · Pick the sound
Six to choose from: fart, ahem, scream, knuckle crack, whip crack and rimshot. The fart is the default. You will not miss it and it will not startle you. It plays on every single crooked reading, so at the default pace once a second until you sit up. The sounds ship inside the page, and nothing is downloaded.
4 · Trust the trend, not the degree
How far your head juts forward is estimated along depth - the least certain axis a single camera has. So a snapshot is soft and the trend is not. The bar strip shows the day, the curve below shows the days; three red bars in a row mean something, one red bar between green ones is a moment. Pictures with nobody in them do not count at all.
5 · Look again in two weeks
Whether anything is changing does not show in one afternoon. At one picture a second a working day is tens of thousands of readings, so the individual ones are cleared after two days - the daily row from them is kept forever. The comparison „last 7 days against the 7 before“ is the real answer to „am I getting better“.
来源：Hacker News · deshrimp.com