How Do 3D Glasses Work?

3D film viewed without glasses is a very strange sight and may appear to be out of focus, fuzzy or out of register. so you need 3d glasses to watch it.

In order to see things in 3D each eye must see a slightly different picture. This is done in the real world by your eyes being spaced apart about 2 inches (5 centimeters) so each eye has its own slightly different view. The brain then puts the two pictures together to form one 3D image that has depth to it.In making movies ,two cameras photograph the same image from slightly different positions to create these images, then the same scene is projected simultaneously from two different angles in two different colors, red and cyan (or blue or green). Here's where those cool glasses come in -- the colored filters separate the two different images so each image only enters one eye. Your brain puts the two pictures back together .

Although the red/green or red/blue system is now mainly used for television 3-D effects, and was used in many older 3-D movies. In this system, two images are displayed on the screen, one in red and the other in blue (or green). The filters on the glasses allow only one image to enter each eye, and your brain does the rest.

You cannot really have a color movie when you are using color to provide the separation, so the image quality is not nearly as good as with the polarized system.At Disney World, Universal Studios and other 3-D venues, the preferred method uses polarized lenses because they allow color viewing. Two synchronized projectors project two respective views onto the screen, each with a different polarization. The glasses allow only one of the images into each eye because they contain lenses with different polarization.