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Stereoscopic Effects

Page history last edited by lindaliang_o.o@... 9 years, 2 months ago

It’s a typical lazy Sunday morning; it’s noon, so naturally, it’s time for breakfast. You grab a bowl of lucky charms, plop down on the couch, flick on your TV and BAM! There’s a sexy looking burger revolving gently under your nose, engulfing your chin with realistic-looking wisps of steam as an equally sexy male voice draws your attention to the soft bun, dewy lettuce, dripping cheese, and juicy patty, now only $1.99. Bored, you begin to channel surf.


You’re probably thinking that the scene above didn’t actually happen, and you’re right. But if you doubt that it can happen, think again! Thanks to stereoscopic technology, that scene may very well become a reality, soft-core burger commercial and all. If you want to know more, READ ON!



1 What is it?

2 How does it work?

          2.1 How do you do it?

          2.2 3D Glasses

                2.21 Anaglyph

               2.22 Linearly polarized

               2.23 Circularly polarized

3 Other applications

4 Cool links


What is it? 

Stereoscopic technology, which is really just an obnoxious way to say 3D or 3-dimensional effects, is a technique or process that creates the illusion of three dimensional objects in images, where size, depth and distance are all perceivable. Stereoscopic effects are typically referred to as 3-D imaging. Stereoscopic effects are most prominently seen in cinema, where there has recently been a huge resurgence in 3D movies with hugely successful movies like Avatar. 


How does it work?

Hold your finger in front of your face and focus both your eyes on it. Close one eye, still observing your finger. Now close the other eye while still observing your finger. Eh? Did you see that? Woah, your finger moved! No, it didn't. This is called disparity – the different view point of each eye. Our eyes are typically separated by a distance of 6-7cm which is a significant enough difference that when the eyes are presented with an image, the center of focus of the image seen is noticeably different for each eye.  These two views merge together as one single image to give you depth perception, which saves a lot of time since you can gauge exactly how far you have to reach for your keys as you're heading out, instead of groping around on the counter. This is also why if you place your hand over one eye, your depth perception is dramatically decreased which will absolutely increase the likelihood of an impromptu game of catch. Also, since the distance of an object determines how much your eyes must 'swivel' inwards, this angle of convergence is another key factor in stereoscopic technology.


How do you do it?

Stereoscopic effects are created with two pictures taken from slightly different angles to mimic the natural disparity of your eyes. The resultant effect is the illusion of 3D. The very first stereoscope, as well as novelty toys, used a lens to direct each eye to the correct picture; however, you can create this illusion simply with your eyes (see "Cool Links" 1). 


For more understanding, here's an image you can refer to:


The picture on the left is representing the image you see with your left eye, and the image on the right is the image seen from the right eye. As you can see, the items in each image are very slightly altered. After layering the two pictures with 50% transparity, this is the result:

As you can see, most of the items were in different places, however, the mushroom was in the exact same spot. This is what will create the 3-D effect; the mushroom will be the base of the scene. Refer back to the original two photos and notice that both the heart and the earth are closer to the left border in the second picture as compared to the first picture. This means that they will pop out closer to you. In contrast, the fish is closer to the left border in the first picture, and farther in the second. This means the fish will appear behind the basement of the scene; it is the "farthest" away from you.


This same concept is applied to motion picture, which is just a series of images. Stereoscopic effects are created one of two ways; they are either filmed from two different camera angles to organically create disparity or added later with computer editing, with the exception of computer animated films which can only be computer edited. These two images are superimposed over one another and presented simultaneously. Seen with the naked eye, the viewer will not experience the 3D effects since both eyes are seeing both images at once, instead of their designated images. To rectify this problem, special polarized glasses must be worn as part of the 3D process.


3D Glasses

Ah, remember the good old days of cheap, flimsy red/blue cardboard glasses? You know... the ones that rendered your sight into a dizzy but colourful mess of visual upchuck. Not to mention how cool they looked. To their credit, these glasses were at the forefront of the 3D wave that swept the film industry. Unsurprisingly, their technology is quite different from their sleek RealD cousins that are widely used today.


Anaglyph Glasses

Anaglyph glasses are named for their predecessor pictures that used a combination of red and cyan processed images superimposed slightly off center of the main original image. These images were then viewed through glasses, pictured at right, with a red filter for the left lens and a cyan filter for the right lens. The role of the coloured lenses were to designate the appropriate image for each eye, again for the purpose of mimicking natural disparity, thus creating a stereoscopic illusion.


Anaglyph glasses are indisputably of the lowest quality with regards to performance, not to mention physical construction, as they render the colour down to wasted effort and overall provide a low quality 3D experience. Though the most popular colours used are red and blue, any complementary coloured lenses will work, as long as they are coordinated with the image. 


Linearly Polarized Glasses

With linearly polarized glasses, disparity 






















Most 3-D movies seen now are viewed through the technology of RealD, produced by RealD Inc. RealD is a projection technology that uses circularly polarized lenses to produce the "3-D" that we see in movies. In this technology, two images are projected onto the same screen through circularly polarized filters, the images are then perceived by the viewer who is also wearing circularly polarized lenses. The result is the right-polarized light passes through only the right polarized glasses, and the left-polarized light only through the left, leaving one image for each eye. 


Now, you may be asking, what is polarization? Polarization is the nature of a wave's electric field at a point in time.  Since light is a transverse wave (waves that oscillate perpendicular to the direction of the energy), it can be a linear of circular, depending on the nature of the electric field. Most movies produce circular polarized waves (the oscillations travelling in a circle either to the right or to the left), which is what we are filtering through the glasses so that each eye is only perceiving one image. 



In the recent explosion in popularity of 3D effects used in movies, stereoscopic technology seems like a fairly modern invention. However, the very first stereoscope was invented in 1833 by a physicist and Professor of Experimental Philosophy named Sir Charles Wheatstone. Up until the 1920's, the stereoscope could be found in every family home and was the main source of entertainment, much like the TV today and they were used for purposes such as story telling and education. 



Though 3D effect films have existed since the 1950's, they were not a dominant aspect of cinema. In the 80's and 90's, with the celebrated birth of Disney animated films, stereoscopic 3D effects saw a huge resurgence from its largely dormant period and became increasingly mainstream with the creation of computer animated films and further advancements in technology.


Cool Links!

This video does a fantastic job of teaching you how to merge two side-by-side stereoscopic images into a popping 3D image!

1. http://www.youtube.com/watch?v=zBa-bCxsZDk&feature=related



Comments (2)

lindaliang_o.o@... said

at 10:03 am on Apr 21, 2011

RACHEL : ) LOL how do you move the image to the right side of the page, like you did with the black and white picture?
i space-barred it to the right, but then i cant write any text on the side > < you know what i mean? :p
thank you ^.^

Rachel Seong said

at 11:19 am on Apr 21, 2011

haha! it took me a while too :) - just right click, click on edit picture and then choose your alignment

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