3D ImageYou may have gone to the movie theater in the last two years to watch Avatar in 3-D, or perhaps you waited until it came out in Blu-ray to watch it at home in front of your TV lift cabinet. Regardless, you likely think that 3-D technologies are cool and will clearly be part of the entertainment industry’s future. But have you ever wondered how 3-D works? We uncovered some of the secrets of 3-D technology and we would like to share them.

Have you ever held up a pencil or finger and looked at it with one eye closed, then the other one closed? You’ll see that the image is the same, but it has a different perspective. This is “stereoscopy,” and it’s how the eyes and brain work together to create an impression of a third dimension. Our eyes are roughly 50 mm to 75 mm apart, and each eye takes in a different perspective, triggering the brain to do some crazy geometry to make up for the disparity between both images. It is this disparity that creates “3-D”.

So when we use technology to replicate this disparity (or 3-D), we use funny-looking (or stylish) 3-D glasses and silver-coated projectors to feed each eye a different perspective of the same image on the screen. That made everything sound simple, didn’t it?

Now we need to address the technology that goes into filming and showing a 3-D image onscreen. We know how the eyes and brain work together to receive and decipher images, but what are images onscreen except light and color. The first 3-D glasses we used to wear were those red and blue ones – having a different color lens for each eye. This helped separate layers of images by having some in red and some in blue, thus giving us a layered 3-D effect, but they couldn’t compensate for rich colors and often they “ghosted” images.

Today we rely on polarized glasses, which can give light different orientations. For instance, these glasses could project light with a horizontal polarization for one eye and a vertical polarization for the other. However, to view a 3-D movie with this technique, you’d have to keep your head completely still (ever see A Clockwork Orange?). To address this issue, 3-D glasses are now made to use rotational polarity, so a film can give two different spins – the glasses then pick up those distinct spins and lets one eye pick up the clockwise spin while the other interprets a counter-clockwise spin. Now you can tilt your head, rest it on your partner’s shoulder, or lean back to enjoy the 3-D film.

Additional 3-D effects come into play and are tweaked via specialized cameras and computer graphics, but “seeing” in 3-D all comes down to playing against the disparity between your eyes and your brain. Without getting it just right, there is no effect and there is no recording-earning film like Avatar.

Share with us your favorite 3-D film to date. Why did you like it – was it for the effect, the story or both?