*Actually just lichens and a moldy avocado
Take your right hand and cover your left eye. Keeping both eyes wide open, look at an object halfway across the room. You can now “see through your hand.”** Your brain compiles the world around you into a single image that we intuitively equate with media such as photography and video, but in fact (as evidenced by your brain ignoring your hand occluding half your visual inputs) this mental image of the world is compiled from two different perspectives. Therefore, the processing side of the human visual system is very well set up to interpret sterographic images. Some people complain about this but you can always file a bug report with reality if it becomes too much trouble.
Human binocular vision works pretty well at scales where the inter-ocular distance provides a noticeable difference in perspective, but not for objects that are very close or very far away. This is why distant mountains look flat , and we don’t have good spatial intuition for very small objects, either. Stereophotography can improve our intuition of objects outside of the scales of our usual experience. By modifying the distance between two viewpoints, we can enhance our experience of perspective
For these stereo photos of lichens, I used a macro bellows with a perspective control lens. This type of lens is use for fixing vanishing lines in architectural photography or for making things look tiny that aren’t, but in this case it makes a useful tool for shifting perspective by a few centimetres.
The images below require a pair of red blue filters or 3D glasses to shepherd a different perspective image into each eye, for spatial interpretation in your meat-based visual processor.
Another way to generate the illusion of dimensionality is parallax. This is a good way to judge depth when your eyes are on opposite sides of your head.
**If you currently have use of only a single eye, the same effect can be achieved by holding the eye of a needle or other object thinner than your pupil directly in front of the active eye. This is something that Leonardo (the blue one) remarked on, and suggests the similarities in imaging with a relatively large aperture (like your dilated pupil) and an “image” reconciled from multiple images at different perspectives, e.g. as binocular vision.