Comment by dmd

17 hours ago

The app doesn't have to do this itself, phones do it for you. ARCore on Android, ARKit on iOS.

Oh yeah I mean how do the phones do that. I guess it uses dead reckoning with visual cues and some machine learning.

  • on iPhone 12 Pro Max and later (maybe only on Pros, I forget) they have a LiDAR sensor built in, allowing for impressively accurate 3D scans of objects with a free app like Scaniverse. But yeah I think AR was the intention there

  • Your phone has an accelerometer, which can be integrated twice to result in slightly accurate dead reckoning; just keep accumulating 3-vectors with every time-slice. That's a helluva lot easier than visual cues.

    • "slightly accurate" is the correct description, though -- dead reckoning on a cell-phone-class IMU accumulates drift too quickly to keep objects anchored in space for more than seconds at a time. You need something (visual odometry, SLAM) that provides long-term stability, even if it has short-term noise or poor availability, to fuse in.

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  • In my experience, on Android, it definitely relies on camera: AR doesn't work in dark room, and barely works in slightly-lit room. So it must be fusing camera + accelerometer + ...