Tuesday, October 4, 2011

Do You Want to Watch 3D Cinema At Home

By John Woods


Going to the movies is one of my favorite things to do. I probably always will. Now that we have 3D movies I'm like a little kid in a candy store. You don't have to twist my arm to get me to experience the joys of a well made 3D experience. Having four little girls who enjoy a 3D movie as much as I do gives me the perfect excuse to see all the latest CGI animations coming out. 3D works by making sure each eye sees a slightly different picture than the other with each image representing the perspective of each eye.

As each eye perceives the world from a slightly different perspective due to them being about 2 inches apart this effectively mimics the way we see the real world and creates a more realistic 3D image on a 2D screen. Every 3D image or movie you view uses this same principle but may go about it in a slightly different manner.

Once a popular method anaglyph is now more of a novelty due to its poor picture quality. In case you don't know the term anaglyph refers to the red and blue glasses which are usually made out of cardboard. The images for each eye have either a red or blue tint. The glasses filter out the correspondingly colored image so each eye sees a separate image. This works to a degree but the colors are somewhat muted so you wouldn't want to watch a top notch feature length movie with them.

Active shutter glasses use a method that is technically known as alternate-frame sequencing. Each eye has its view blocked by the lens going dark when the image that it is not supposed to be seeing is on the screen. This is the reason a TV needs to be capable of at least a frequency of 120Hz. Divide this by two and you have the required 60Hz for each eye that is needed for smooth animation. Even higher frequencies can ensure a flicker free experience for the vast majority of viewers. These higher frequencies are becoming the default standard of new model TVs and projectors.

Using active shutter glasses can have its downsides. Perhaps the biggest disadvantage is the need for a power source for the glasses. It can be provided via cable tethered to a power supply or via batteries. When you have a large family that can add up to quite a mess of cables or quite a lot of batteries. The major advantage is that the technology has been around for a while now and projectors and TVs using this method are relatively cheap. This is excellent if you only need one or two pairs of glasses.

Technological research has created new ways of displaying 3D imagery in the home. Polarized light stereoscopy, currently popular in cinemas, is now being made available in the home marketplace through the use of projectors. It's a very efficient way of creating 3D images as both images can now be displayed on the screen at the same time. Special polarized lenses in the glasses are polarized to only let in the correct image while blocking the other.

While it has some very good advantages the one major disadvantage it has at the moment is the cost. As it's still relatively new technology equipment is rather expensive. The images are projected so you will also need to buy a silver screen to get the best effect. A silver screen is needed to keep the light polarized so the image remains crisp and clear.

I believe polarized light stereoscopy will become the dominant method of 3D in the home eventually as costs decrease over time. The glasses are lighter, cheaper and don't require batteries. You can also have a more widely dispersed audience as the 3D effect is viewable from more angles. Shutter glasses also have a tendency to darken the image by about 20%. You get a much brighter image with polarized lenses as they only block about 10% of the light.




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