If that motion is projectively consistent with binocular disparity, the viewer will perceive — via stereopsis — the illusion that the glint occurs at a different depth than the surface that produces it.
In the 1970s, Gabriel Liebermann discovered that a scratch in the shape of a circular arc produces glints whose motion is approximately consistent with binocular disparity.
The phenomenon was independently discovered in the 1990s by William Beaty[3] who popularized a method of making hand-drawn holograms using a compass (drafting).
[5] If one were to view that geometry as a 3D reflective surface under collimated light, one would observe glint motion that is consistent with horizontal parallax.
Instead of scratches, it employs very fine doubly curved mirrors or refractors, each computationally designed to produce distortion-free parallax over a wide field of view.
One interesting property of the foliation approach is that it yields solutions for non-flat holographic surfaces and for unconventional viewing geometries.