Photograph a bottle, say what it holds when full, and this measures what is left in it —
by spinning its outline into a solid of revolution. It also tells you how much to trust the number.
Nothing loaded yet.
Open a photo or a video of the bottle, or try the demo.
Drag the handles onto the bottle: base and cap set the axis, the one on the right
limits the search, and the coloured lines are the surface and the level it was full to.
A bottle whose contents are known exactly, so you can see the measurement next to the truth.