I don't know how Google does it, but it's possible to extract 3d information from a 2d sensor. You either need a variable focus or phase detection in the sensor.
Very cool. Yes, probably? I'll have to think about the relationship between image quality and the fidelity of the derived phase measurement, because it's not obvious how good a camera needs to be to be "good enough" for a secure system.
I guess the task is to design an experiment to test the error between phase inferred from intensity in a digital camera by Huygens-Steiner and a barycentric coordinate map And far more expensive photonic phase sensors.
Is (framerate-1 Hz) a limit, due to the discrete derivative being null for the first n points?
> This means that hard-to-measure optical properties such as amplitudes, phases and correlations—perhaps even these of quantum wave systems—can be deduced from something a lot easier to measure: light intensity.
IDK what happened with wave field cameras like the Lytro. They're possibly useful for face ID, too?
Doesn't that mean that any camera can be used to infer phase (and thus depth for face ID, which is a high risk application)?
> variable focus
A light field camera (with "infinite" focus) would also work.