Asked in
Eyes
Movies
Technology

Why do Real D 3D glasses work in the cinema but they wont work with any other 3D images at home Are there any images that do work?

Answer

User Avatar
Wiki User
November 08, 2011 8:18PM

Real D 3D movies work by projecting two copies of the movie onto the screen, one after the other in quick succession. One series of frames is from the perspective of the left eye, while the other is from the perspective of the right eye. The left and right projections have different light polarizations. The left lens of the 3D glasses allows the light from the left projection to be seen by the left eye, but prevents light from the right projection being seen by the left eye. The right lens does the opposite, allowing only the right projection's light to be seen by the right eye. This has the effect of making the right and left eyes see slightly different versions of the movie, each from a different perspective, just as occurs when viewing a real-world scene. The human brain naturally combines the two two-dimensional images into a single, 3-dimensional scene.

This doesn't work at home on a television or monitor because the monitor is not projecting two different images and even if it were, it can't polarize the light from each image so that it's filtered by the lenses.

In Addition:

  • Traditional red / blue 3D images use the same principal of filtering light for each eye, but use color as the filter instead of polarization, and therefore do not work with Real D 3D glasses.
  • The glasses themselves are not tailored to a specific movie or theater. Real D 3D glasses should work with any Real D 3D movie.
  • Real D 3D is a proprietary item belonging to REALD the company and in essence what happens is movie theaters buy a item that fits over the lens of their projector that projector shoots the image through REALD'S apparatus and then projects onto the screen therefore without that apparatus you have no REAL D 3D and rather only 2D... hope that helps ...check out amazon though for some more comfortable 3D glasses rather then the cardboard stuff.
  • The "3d glasses" have a horizontally polarized filter in the left lens and a vertically polarized filter in the right lens. The cinema uses a projector with two separate images on the film. The left image is projected through a horizontal polarizer and the right image is projected through a vertical polarizer. The two images have slightly different 'perspectives' because they were recorded using a camera with two lenses, one for left, the other for right (just like your eyes). This system generates a combined stereoscopic image which is synchronized and which is how the 3D effect works. Incidentally the sound is recorded in the same way which is how you get stereo (or even surround sound) in the cinema.
  • As you probably now realize, you cannot reproduce this effect with your home cinema or TV system because you don't have the two separately polarized images. TV's only give un-polarized light and home cinemas don't have the polarizers fitted either.
  • If you wanted to reproduce the effect at home, you would have to have both the left and right polarized images projected from separate sources, and since only the cinemas have access to them its very unlikely that you could replicate the system.
  • The above answer is correct for the recording process and discusses basically how 3D movies work, Real D which is what asked works as follows; Its nothing to do with the curvature of the screen sorry to say, the only impact the screen in the cinema has is how much light it reflects back to the eye. (IMAX screens have a silver reflective paint for example to make sure the ray of light are reflected straight and strong to your eye).
  • The reason why, much to my disappointment, you can't have 3D movies on your home TV is because of polarization, which is how the 3D thing works. The projector in the cinema projects alternate frames, each frame from a slightly different perspective to create the 3D stereoscopy. Basically each alternate frame uses a different circular polarization, L frame is clockwise, R frame is anti-clockwise. Those 3D glasses you use are also polarized, the left eye with a clockwise filter, the right with an anti clockwise filter. So the left eye only lets in frames frame one perspective and the right eye from the other.
  • So to answer you question, the reason why that doesn't work on your home TV, is because the TV can't produce polarized images, let alone alternating frames with different circular polarization attributes. So if you want 3D at home, either wait to purchase a 3D TV along with 3D blu-ray, use the dodgy red blue (found in Shrek and others), try out nvidia 3D vision or play around with existing 3D monitors like Zalman.