JohnQ
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3D movies are able to exist because people have what is called binocular vision. This means we use two eyes in conjunction to create a single image. For very distant objects, binocular vision does little but increase our field-of-view. When objects get within about 20 feet, binocular vision allows us to notice differences in depth. That is, we can tell how far an object is away from us and if it is getting closer or further away. With only one eye, we can still judge distance to some degree, but the accuracy of the measurement in our brain is greatly decreased. One good test of this is to try to catch a thrown ball with one eye closed. You will notice the difference in the difficulty.
Older 3D movies used red and blue colors on a screen in combinations of two separate pictures. Viewers wore glasses with one red lens and one blue lens so the eye with the red lens could only see the blue images and the eye with the blue lens could only see the red images. This allowed pictures to be presented in varying depths.
Newer 3D movies use a system of polarization. In this type of 3D, viewers wear dark-tinted glasses with lenses that appear the same but are different in polarization. The movie is projected onto the screen with two different polarizations. This means the angle in which the light is oriented is controlled and made to move in a specific direction instead of all directions at once like normal light. Each of the lenses is set to filter out one of the polarized images. The different images presented to each eye allow us to see the movie with different depth ranges.
 Posted 5356 day ago
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