How Does Stereoscopic (3D) Vision Work?

How Does Stereoscopic (3D) Vision Work?

3D vision is the direct effect of our brains merging the images from both of our eyes together. Each of our eyes creates a single two-dimensional image, but the brain is able to interpret depth when it merges both two-dimensional images and understands the difference between them. We call this ability stereoscopic vision.

Why Do We Call It Stereoscopic Vision?

The prefix stereo- comes from the Greek word for solid, and the suffix –scopic comes from the Greek word for looking or examining. We use the prefix stereo- in English to denote objects or abilities that operate in multiple dimensions. A typical example is stereo sound, or stereophonics, which is sound emitted from two or more speakers to emulate natural sound in a three-dimensional world.

Turning 2D Vision Into 3D Vision

The two-dimensional images our eyes see separately are only able to give us information on length and height. Based on phenomena such as foreshortening, in which length, height, or both are shortened due to perspective, we can make educated guesses as to the third dimension, width, of objects in our field of vision. But they would be only guessing – stereoscopic vision is what allows us to perceive the third dimension.

Your brain is constantly and instantly giving you information about the third dimension, and most of it is subconscious. To consciously understand what your brain is doing when it creates a 3D image, hold a small object close to your face, about 8 or 9 inches away from your nose, but don’t focus on it. Focus instead on a distant object. When you do, you’ll see the nearby object split into two slightly see-through images.

The Brain at Work in Stereoscopic Vision

The two images are separated in your view because your brain is merging the two images it sees of the distant object, not the near object. If you train your focus on the near object, you’ll merge the two images and your brain will calculate the difference between them to create a map of depth. This is the experience of seeing in 3D.

While you’re focused on the nearby object, all objects in the background will split into multiple images. Because your brain only concentrates on its point of focus and blocks out extraneous information, you don’t notice it on a regular basis, but in your field of vision there will always be objects for which your brain has merged the images and objects for which images are separated.

Though we are no longer dependent on our 3D vision to explore and hunt, we do use it to interact with the civilized world we’ve created. 3D vision allows us to perform daily activities with speed and accuracy, but because the entire process is subconscious, we take it for granted.

Some children and adults are unable to properly converge or team their eyes. They constantly or intermittently see multiple two-dimensional images that do not match to create a 3D image, or the brain may ignore one image from the weaker eye and therefore not see in 3D.   Though it takes lots of hands-on training, with hard work it is possible to correct convergence insufficiency and other eye teaming issues like suppression, double vision, eye turns and lazy eye to rebuild stereoscopic vision.

OCVT specializes in and has experience with correcting convergence insufficiency and eye teaming problems. We can combine our efforts with vision therapy services to help correct vision efficiency and processing problems in children and adults.

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