visual geometry depends on eyeballs, optic nerves, rods, cones -- all physical geometries of their OWN. If I visually/physically observe an eye operation by a surgeon, I will visually perceive the eyeball, optic nerve, rods and cones --- they will seem to have their own physical geometry according to the visual geometry of my OWN eyeballs, optic nerves, rods and cones. It is a concentric circle of increasing intrigue.