I recently went to see Avatar in 3D. While the film was very good, I can’t say with certainty that there was anything groundbreaking about the 3D effects. For 1,there is a darkish tint throughout the film which reduces the color saturation. Occasionally you almost feel like you are looking at a monochromatic film (or that perhaps you’re dreaming).

Having said that, this is not the topic of this post. The post is meant to educate and create awareness about stereoscopic(3D) technologies, something which has fascinated me for more than half a decade now.

The underlying concept behind creating anything 3D is the same no matter what technology you use. Our perception of depth comes because we have 2 eyes. The 3rd dimension disappears when you close any one eye( Try it). So in case of a 3D picture or a video, the idea is to present 2 different views to the 2 eyes. If you can successfully present 2 separate views of the same picture/video to each eye, you will be able to perceive depth.

So what does one do to create a 3D video/photo and put it on youtube?

For video you need 2 cameras.  No extra ordinary camera but any 2 cameras that can shoot videos.It may be a good idea to tie them up with a rubber band.

After this you need to turn both the cameras on and shoot the video in both of them. So that the 2 cameras get a shifted version of the same video.

Or better you can simply follow these youtube instructions:

• Use two cameras arranged like a pair of eyes
• Start both cameras recording simultaneously
• In your video-editing program, place the footage for the left and right eyes together in the frame side by side, with the right eye on the left and the left eye on the right
• Upload your video!
• Edit your videos tags and add yt3d:enable=true. If video is widescreen, add yt3d:aspect=16:9

So what happens when you do that? The Youtube 3d player becomes active and automatically shows your video in your desired formats. Something like this

If you’ll see this video on youtube, you will find the various 3D options such red/cyan, cross eyed, parallel eyes etc? Let me explain to you what some of them mean:

The first 6 options refer to filter glasses.

For example: red/cyan means you need a pair of glasses with red filter on the left and cyan/blue on the right. There is absolutely nothing special about these glasses and if you do not have them, simply using a good and appropriate cello phane paper will do.

Cross eyed/Parallel are techniques to view 3D without any special equipment but with a special eye exercise.Basically in the cross eyed technique, you need to see the image/video by crossing your eyes so that a 3rd image emerges in the center of the 2 images and that image will have depth.

The parallel eye technique is slightly more difficult to carry out. In this your left eye sees the left image and the right one sees the right image. The 3rd image then appears at the center which appears to be slightly bigger than the other 2.  This technique puts a lot of strain on the eyes so you must be careful.

At the Cinema Halls

Now these are the only techniques to watch videos and images in 3D on your computer screen. But if you have seen any 3D film on theatre, you are probably wondering why the same technology is not used for 3D on ordinary computers. Well this is because the 3D on theaters uses special polarized projectors which work on the principle of plane polarized light. The glasses at the theater are polarized glasses placed perpendicular to each other.

If you haven’t studied physics, just imagine 2 light rays one of which is a bunch of vertical lines and the other is a bunch of horizontal lines. Can the vertical bunch pass through a grid of horizontal slits? It cannot but it can pass through the horizontal slits.  Vice versa for horizontal bunch. This is what the polarized glasses do. If you go to watch Avatar in 3D, then do this experiment with your glasses. Take them in your hand, and rotate them perpendicularly. You will find the views (that is the respective tints) are swapped. Also, reverse the glasses and then view a scene through them. Chances are one of them will completely block the view and you will see a dark screen.  And when you will rotate the glasses by 90 degree, the other glass will block the view.Basically the images are now created using 2 light sources which can pass through only one lens.

The reason why this technology is preferred over filter glass technology is the fact that it does not interfere with the color fidelity as much as the filtered glasses do. However, because you need a special projector to display such polarized light, very few theaters are able to run them.

As for James Cameron’s Avatar. There is nothing path breaking about it as far as the stereo 3D aspect of it is concerned since it is an ordinary polarized stereo only, the one which films such as Chhota Chetan used. However, it was very hard to believe that you were looking at a partially animated film. The 3D gimmicks are not really that many. If you want gimmicks, you should probably see Journey to the Center of the Earth or perhaps, Spy Kids 3D.

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Related posts:

1. Stereograms