But you cannot focus where you want, so it’s not 3d but layered 2d. In a 3d emulated image you cannot focus on a background object and even if you could the interpupillary distance would be the same and so the focusing one. Our image processing in the brain uses such information to calculate, that’s why you can approximate the dimension of an object and distances in real life but not in a picture even if it is a 3d one.

> Your eyes focus "into" the VR scene, not at the screens one inch from your eye.

3D head gear like Oculus have optical systems that move the physical screens virtually to a much greater (and comfortable) distance - most people can't even focus objects closer than about 10 cm.

That's not what I meant. Rather, even that virtual 3D screen is still at a fixed apparent distance from your eyes, unlike a natural scene that contains objects that are father or closer. Such objects scatter light not only at different angles for the two eyes, the bulk of the 3D effect, but also at different internal convergence, requiring the eye's lens to deform and compensate.

This is an effect current tech cannot reproduce, leading to a nauseating and tiring viewing experience - as if the whole immersive virtual world wasn't already.