It's no surprise that Avatar recently won the Oscar for Best Visual Effects. Avatar's incredible critical and financial success has ushered in a new renaissance of 3D filmmaking.

And while the technical wizardry of Avatar may seem wildly advanced, the actual science of 3D images is elegantly simple.

Depth perception is important for seeing objects in 3D. We perceive depth because we have two eyes which both face forward in our heads. The same image is seen in a slightly different position by each eye, though both are looking at the same thing. These two images are combined together by our brain to determine how distant an object is and thus we see depth. This is a phenomenon known as stereo vision.

So the secret to creating the illusion of 3D is not that complicated — we just need to find a way to have each eye see the same 2D image on screen in a slightly different position. The challenge is to make sure that the left picture is only seen by the left eye and the right picture is only seen by the right eye. There are different ways this can be done (see How 3D works).

Did You Know?
Older 3D technology gave some people headaches or nausea after long viewing. This is because the separation between the left and right image was not perfect, making the viewer feel ill.

Technology has come a long way from old-fashioned 3D images, called anaglyphs, where the left and right images were separated using colour filter glasses. A major 3D technology used in many Canadian theatres uses light polarization. Light polarization is used in IMAX films (linear polarization) and in the more common theatre experience offered by RealD (circular polarization).

Did You Know?
Over the next three years, about 40 films are scheduled to appear in 3D.

Light is made up of many kinds of waves that vibrate in a lot of different directions when it travels. Linear polarization forces the light to vibrate in only one of two directions: up and down, or side-to-side. Circular polarization goes one step further and forces linear light to travel in either a clockwise or counter clockwise motion.

The RealD 3D theatre experience uses polarized lenses that take advantage of this physics concept. The movie projects two images that are superimposed onto the same screen. They use a polarizing filter or lens in front of the left and right projectors, which match the polarized lenses in each of the left and right eyes of the glasses that are worn to watch the movie. These filters only allow light that is similarly polarized through each eye of the glasses. This ensures that each eye sees a slightly different perspective of the image on the screen, creating the 3D effect.

Another way to give the illusion of three dimensions on screen is to use shutter glasses which are synchronized with images projected on a display. When the left image is shown, the vision in the right eye is blocked, and vice versa. This occurs so fast that the brain is fooled into thinking it’s just seeing one image instead of two.

If you want 3D at home, check out Nvidia 3D Vision. Nvidia (the company that makes the graphics hardware for Playstation 3) has produced an amazing 3D software update for PCs that have Nvidia graphics hardware. The Nvidia 3D glasses are shutter glasses — that flip between totally opaque (meaning totally black) and transparent (meaning totally clear) so fast that your eyes can't tell it's happening. The monitor produces images in sync with the shutter lenses switching on and off so that each eye only sees the correct image. The effect is truly amazing since it can be used with hundreds of major computer games.

So, movies, computers, video games, what’s next for 3D? Soon it will be everywhere! The first 3D television channel is set to launch in 2011.

Learn More:

A Brief Overview of 3D Technologies

Wikipedia – 3-D film

Suggested Links:

Nvidia 3D Vision

RealD

Article first published on March 24, 2010.

Russ Dickson

I am a PhD student in the Department of Biochemistry at the University of Western Ontario. My work is in the field of bioinformatics, the science of using computers and information science to solve problems in molecular biology. When I am not writing biological software, I play hockey and make games for the PC, iPhone and Nintendo DS.


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