How does 3-D work in the movies?

The common method used for 3-D movie is the polarized light. Two pictures are beamed on the screen from two polarized light sources that are 90 degrees to each other. You wear the polarized glasses that are orientated such that the left eye will see one of the pictures while blocking out the other. Similarly, the right eye will see the other picture while blocking out the first. As the movie is filmed as a 3-D movie, there will be two cameras slight space apart, just like our eyes are. When your brain combines the left and right images, slight differences in the pictures will give the perception of distance. The closer the objects are to you, the greater the differences.

In earlier movies, when polarized light was not available, the Red and Blue filter glass were used. The idea is similar as there were in essence two pictures on the screen, one is Red in color and the other is Blue. Hence the Red and Blue glasses will accept one picture and hide the other. Again, the combined picture will give a 3-D effect. The disadvantage of course, is that we are now limited by certain colours. Today, 3D polarized light technique is much better.

Can 3D movie be achieved without glasses? Actually, years back I watched a documentary that had a 3D image displayed on our normal TV and it would be viewed without glasses. Indeed, as I view it, I could see the 3D BUT there was a catch. The technique was to keep moving the viewing angle. (You can try this, close one eye (your view is now MONO) and keep moving left and right (you can see spacing between near objects move more than spacing between distant objects). Of course, view alternation was done at a higher frequency. The process works but the picture is a little jumpy.

There are other techiques, such as using holograms. Commercially, 3D viewing did not deliver the revenue returns as was hoped for. The cost of production for 3D movies is much greater and the equipment to show them also has cost impact. That is why, a large part of the movies are still in 2D, added by better sound effects and higher definition. But who knows, someday, someone would invent the ultimate 3D without glasses at a commercially viable cost and then everyone can enjoy the ultimate movie experience.

there r 2 different pictures in a 3d picture, they are both picked up by the different lenses to make it appear different depths, i am pretty sure it has to do with wave lengths of light , and i think that's why the lenses are different colors...there are 3d pictures you can see with the naked eye, go 2 yahoo images and search for "magic eye", they are images that you look at, and after a short time your brain separates the image from the back round, so that u see a picture in 3d , however the entire picture is in a pattern, so there arena;t different colors