Three-Dimensional Image, or 3-D image, flat image enhanced to impart the illusion of depth. Humans perceive the world and the objects in it in three dimensions-breadth, width, and depth. This seemingly simple phenomenon is the product of a complicated set of interactions between our eyes and our brains that is still not entirely understood. Our eyes are spaced about 6 cm apart, which causes each eye to receive a slightly different image. The brain fuses these two images into a single 3-D image, enabling us to perceive depth.

Some of the Things 3-D Vision Helps You With:

Throw, catch or hit a ball
Drive and park a car
Thread a needle and sewing
Reach out to shake someone's hand
Pour into a container
Step off a curb or step
Run downstairs
Climb down a ladder

Why some people have trouble seeing 3D

In order to view 3D stereo images you must have two eyes that work together as a coordinated team. Two working eyes are definitely required.
If you are having trouble seeing 3D, the first thing you need to do is find out whether you have binocular vision and stereo vision. You've got to have stereo vision to experience depth perception and 3D illusions.

Less than 5% of the population have severe visual disabilities that make stereo vision extremely difficult or impossible. This group includes those who have lost an eye or those with severe amblyopia (lazy eye) or strabismus (eye turns -- "crossed eyes" or "wall eyes").

Consider testing your own binocular vision with The Framing Game.

 

The Framing Game

	Focus your eyes on the single brown eye.
	Put your free thumb in front of your nose. Continue to focus on the eye. If both eyes are on, you will see two thumbs framing one eye.
	Now, switch your focus to your thumb. You should see two eyes framing one thumb.