[mrskeltal]

By dipping from various different angles

[agumonkey]

It's a bit like a fluid pet scan, each angle will give partial information, you "integrate" to gather the surface.

Gives me ideas.

[samstave]

Think of the intro to the Ghost in the Shell, where the android body is floating up through a bath, and the manufacturer layer on the body is dissolving and being removed. This method could detect that the material is 100% removed from the body as well as confirm that the body is created exactly to spec.

[anotheryou]

I guess that would be possible, but one has to do some trickery to find false data.

Maybe correlating the exact oposite dip works: Dipping a bowl shows a negative volume then the bowl begins to fill. A dome (reversed bowl) will show additional volume of trapped air at the same point.