Why Do I Need To Wear Special Glasses To Watch 3D?
The reason you need to wear glasses to watch 3D is that a separate image needs to be sent to each eye, with the brain combining the two images into a single image with 3D characteristics. In other words, the 3D process actually fools your brain into thinking it is seeing a 3D image, so it creates one for you.
The way this works with 3D-enabled TVs is that even though there will be several ways a 3D signal can be encoded and sent to the TV, the TV will decode the 3D signal and display the left and right eye information on the TV screen as two overlapping images that look slightly out of focus when viewed without 3D glasses.
Now, some of you are probably thinking that there are technologies that enable you to see a 3D image on a TV without glasses. Such prototype and special application units do exist, usually referred to as “AutoStereoscopic Displays”. Such displays are extremely expensive and, in most cases, you have to stand right in the center spot, so they are not good for group viewing. Also, these units do not do well with rapid motion, they are primarily designed for displaying computer graphics or photos.
Although autostereoscopic display technologies are being pursued and implemented in some settings, this approach to 3D is not mature, or affordable enough, to manufacture and market for watching 3D movies and TV programs in the home at the current time.
source: http://hometheater.about.com/od/hometheatervideobasics/f/why_do_I_need_glasses_for_3d.htm
