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How 3D Glasses Work

By Kevin Styles

Republish: EasyPublish™ Published: 14Jan2011 Word count: 589 Viewed: 272 time(s) Get Free Content For Your Site

Of course when you are using glasses in your everyday life, you are naturally importing the environment in all dimensions available to you. So why do we need special glasses for watching 3-D on television or in the cinema?

Can you even buy glasses online that will enhance your depth perception beyond your current capability? What happens if you wear 3-D spectacles outside - or wear 3-D spectacles in your everyday life? The brain uses several methods to determine depth in the visual field whether one is wearing glasses or not. It has in effect learned over time the natural state of objects seen in everyday life and categorises them naturally by distance, relative height and other factors in order to scale them and so conclude what the depth of the visual field may be.

All of these factors are present also when viewing a 2-D image (such as a television of cinema screen) but they are necessary and not sufficient to provide enough information for the brain to determine depth of field. This is where 3-D glasses come in - to add vital information for the brain to calculate from available information - and now new information added by the spectacles - what the relative position of objects may be and so what the depth of field may be.

The basic concept of providing "stereo images" dates back as far as the mid nineteenth century when stereograms were introduced primarily for entertainment. Instead of glasses, the viewer was presented with a pair of images - one for each eye - which provided a stereo image …each slightly offset …..from which the brain could then transpose depth information and so perception.

The easiest way to consider this without the use of specialized glasses is to look at an image alternatively through each eye. The resulting perspective should be the image that is presented to the eye artificially in order for it to determine perspective - at least in the near field of vision (as all objects out to infinity should appear the same to each eye as the perspective difference of each eye is minimized relative to the distance of field of vision).


Modern systems for 2-D images - such as those presented by "3-D" television sets attempt to overcome these issues and simulate binocular vision through the use of specialized glasses. Essentially these glasses are used to filter out a different image for each eye - and so the spectacles themselves present a different perspective to each eye - and the brain is left t process this information in the same way that was discovered by Wheatstone et al over a century ago.

So although 3-D glasses may seem like a modern marvel, in effect they are reproducing an effect that has long been understood - and used for entertainment - but doing so using the marvels of modern technology and miniaturization.

There are several different types of 3-D spectacles, each of which uses a slightly different means of processing basically the same information and using the glasses to present that information to the eye and eventually to the brain for processing in order to fool it into concluding that the image actually has a 3 dimensions rather than 2.

Thankfully in the real world, you only need glasses to enhance the eye's ability to focus and not to rectify depth perception and so normal glasses lenses will do rather than advanced electronics to fool the eye.

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