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Matter of Vision

How Do 3-D Glasses Work?


The advent of three-dimensional movies was both a revolutionary and a defining moment in the film industry. These movies have the power to sweep the viewers off their feet for real. They come in the form of moving visuals that stir our emotions. Speaking of visuals, how are we able to traverse the scenes along with the actors? It’s the lens through which we view the visuals.

Lens? YES!

The evolution of 3-D glasses have come a long way to offer us the best movie experience. But how does it work? Let’s uncover what’s behind those glasses, shall we?

Stereo Vision

Human beings have two eyes. The vision of both the eyes are almost common. Almost. The right and the left eye covers the same vision from a different angle, and each eye tends to pick up information that the other doesn’t. The left image is presented only to the left eye and the right image is sent directly to the right eye. These images are received together as one by the brain by correlating the similarities and resolving the differences simultaneously. This combined image is known as a three-dimensional stereo picture. Stereo means “solid.” The stereo vision offers you to see an object as solid as possible. An additional perception of the depth dimension makes the stereo vision so rich and special.

Three-dimension

A three-dimension includes three spatial dimensions namely, width, height and depth. This is usually represented in the graphs in terms of x,y, and z. The three-dimension(3-D) movies that we watch are a variation of stereo vision systems. Unlike the stereo visions systems, the technology for a 3-D film is more complicated. Because, the filmmaker tried to seek ways to prevent the left eye from seeing what only the right eye is supposed to view, even though both the images are projected simultaneously on the screen.

The Rise of The Three-dimensional Technology

Anaglyphs

David Gibson of the Eastman Kodak Company reviewed the following:

In the 1890s, when the 3-D systems were first invented, they were called anaglyphes. The left eye image was projected with a red-coloured filter and the right eye image was projected with a blue-green filter via the projector lens. The red and blue-green colours are used here because they are chromatically opposite to each other thereby encoding the vision of each eye respectively. The visual cortex(exterior part of the brain known as cerebrum) of the brain fuses these images into one single scene.

3-D glasses with the same colour were tried as a part of the experiment. It leads to the blockage of light from the right-image projector. Back in the olden days, this system was used to print stereo comic books. Perhaps, the only problem with the Anaglyph 3-D technology is that it works best with monochrome images. Besides, the red and blue-green tints of the glass adds unwanted colouration to the colour of a 3-D film. This was seen as more of a discomfort by the viewers as the view temporarily affected their vision of real-life objects.

Polaroids

Then came Polaroid that developed a polarisation method, exclusively crafted for the 3-D films. The Polaroid technology beams the angle of polarisation for one eye at right angles to that for the other eye, so that one image is transmitted while the other eye is blocked. Moreover, the projectors also project two respective views onto the screen with different polarization levels. In other words, the two different images/scenes/visuals are superimposed on the same screen. This is the reason why we tend to see two glaring visuals on the screen without the 3-D glasses. It was Edwin Land who invented these unicoloured or full coloured polaroid glasses in 1936 and created a history in the field of 3-D movie technology!

Oh Shrek, It’s Us!!!

However, 3-D movies are geometrically incorrect. These movies are a trick to our vision. Because, the distance between both the eyes varies from one individual to another. It’s again our brains that try to perceive things despite the geometrical errors. In reality, the brain can actually not perceive visuals through three-dimension(3-D) unless something is moving. It triangulates between the eyes in order to perceive the 3rd dimension that we discussed earlier — the depth. This means, humans have got tremendous depth perception levels. Indeed, the laurel should go to the depth of the human brains, isn’t it?

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