I don't really know too much about the human body, but this is my rough understanding of how vision works: light comes from a source, like the sun, it hits an object, and then if it's of the right frequency it's reflected by the object and then enters one of your two eyes, where it is refracted by a series of lenses until it's projected onto the retina, where it is absorbed by a photoreceptor cell, which sends a signal via the optic nerve to the brain, which compares the two-dimensional data from both eyes in order to estimate the distances of the various objects, and then constructs a 3-dimensional construct of the world. My question is, how does the eye get the necessary information to create a two-dimensional projection of the world? A beam of light comes into the eye and is absorbed by a photoreceptor cell, but how does the photoreceptor cell know what angle at which the light hit it? Assuming the retina is a spherical surface, it seems to me that you need two pieces of information: what is the angular position on the retinal surface at which the light hits, and what is the angle at which the light hits the surface. Only then can you deduce the angular position of the object that reflected the light, which is what you need to make a two dimensional projection. (Because light from two different places can end up hitting the place on the retina, just at different angles.) So what is the mechanism for finding out the angle of incidence? Any help would be greatly appreciated Thank You in Advance.