3-D+Glasses

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3D imagery relates to light and optics because light is being projected on a screen and using two eyes and your **binocular vision** system you see a 3D image. ======

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 * Binocular vision system **- For objects up to about 20 feet away, the binocular vision system lets us tell with accuracy how far away an object is. For example, if there are multiple objects in our field of view, we can automatically tell which ones are farther and which are nearer, and how far away they are. If you look at the world with one eye closed, you can still perceive distance, but your accuracy decreases and you have to rely on visual cues or focusing distances, both of which are slower. Thus, it is harder to see in 3D. So in order to see 3D images the best you can, you have to use both eyes under modified lenses. ======

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**Stereoscopy**, or 3-D imaging, creates an illusion that makes objects appear three-dimensional but is on a two-dimensional plane. The illusion of depth in a photograph, movie, or other two-dimensional image is created by presenting a slightly different image to each eye.  Three-dimensional glasses are used mainly in theatres to make the viewer see the movie in 3D or in photogammetry. ======

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Stereoscopy is the technique that changes or enhances the illusion of depth in an image by presenting two images separately to the left and right eye of the viewer. The two two-dimensional images are then combined to create a 3D image. Three-dimensional glasses can do this illusion. ======

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 * Polarization- ** Using polarized lenses, two images are projected on a screen. The images are combined to one when viewed through the glasses. You can see images in colour with polarized lenses. ======

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 * Red/Green or Red/Blue Glasses- ** when polarization does not work, like on a TV screen, these glasses are used. Two images display on the screen, one in red and one in green or blue. The filters on the glasses allow one image to be viewed and your brain does the rest. You cannot see colour well with these glasses. ======

http://www.howstuffworks.com/question360.htm
-Miranda