The History of Stereoscopic Viewing . Sabra Baran Professor Don MacLeod May 26, 2011. Euclid, The “ Start” of Stereopsis ( 300 BC).
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The History of Stereoscopic Viewing SabraBaran Professor Don MacLeod May 26, 2011
Euclid, The “Start” of Stereopsis (300 BC) • Supposedly, Euclid (a Greek mathematician) was the first person to uncover how humans achieve depth perception, which is a crucial component of how stereoscopic images work. • He claimed that our eyes receive two almost-twin images, that differ only because of a slight separation of horizontal perspective. Then our brain fuses these two images into a single, three-dimensional picture.
What is Stereoscopic Viewing? In Layman’s Terms: An optical technique by which two images of the same object are blended into one, giving a three-dimensional appearance to the single image.
What is Stereoscopic Viewing? More Technical: Stereoscopic viewing results from complex mechanisms in the brain that form a three-dimensional impression by matching each point (or set of points) in one eye's view with the equivalent point (or set of points) in the other eye's view. Using binocular disparity, the brain can determine the points' positions in the otherwise inscrutable z-axis (depth).
Binocular Disparity …is the difference in image location of an object seen by the left and right eyes, resulting from the eyes' horizontal separation.
How Does Stereoscopic Viewing Work? Two eyes converge on the object of attention The cube is shifted to the left in the right eye's image. The cube is shifted to the right in left eye's image. We see a single, cyclopean, image from the two eyes' images
How To See a Stereogram Without Outside Help… • An autostereogram is an illusion of a 3D surface that needs no machinery, glasses, etc. • There are a couple different kinds of autostereograms: • Single Image Random Dot Stereogram • Wallpaper Stereogram • But first, let me explain the methods of how one can view these autostereograms…
How to See a Stereogram Without Outside Help… • The visualization of an autostereogramrequires an unusual skill: each eye must be targeted to distinct places on the image. • That is the reason some people hardly (or can not) see stereograms. • There are two ways that people can visualize stereograms: • Divergent Viewing • Convergent Viewing
Regular Visualization No stereogram is visible
Divergent Visualization The eyes are: • Relaxed • Focused beyond the image (infinite focus)
Convergent Visualization In order to achieve this type of visualization, the viewer must focus on a point between the eyes and the stereogram:
Depth Map: The distance relationship between any pixel and its counterpart in the equivalent patternnext to it. A Depth Mapcontains information relating to the distance of the surfaces of scene objects from a viewpoint.
Depth Map: • #1 shows luminance in proportion to the distance from the viewer (nearer surfaces = darker; further surfaces = lighter). • #2 shows luminance in relation to the distances from a nominal focal plane (surfaces closer to the focal plane = darker; surfaces further from the focal plane = lighter). #1 #2
Depth Map This Depth Map of a shark with smooth gradient produces a perfectly readable autostereogram.
The Wallpaper Effect • David Brewster (who we will talk about again shortly) noticed that the repeating patterns on wallpaper can leap out in depth. • Adjacent copies of the pattern (Refer to Next Slide) can lure each eye into mismatching their viewpoints. The small differences between adjacent pattern cycles provide binocular disparities that are interpreted by the brain as differences in depth (this is almost similar to the idea that random dot stereograms use…)
Single Image Random Dot Stereogram • In 1979, Christopher Tyler of Smith-Kettlewell Institute, created the first “single-image random-dot stereogram" (also known as random-dot autostereogram). • Instead of using entire horizontal patterns like the Wallpaper Stereogram, only specific dots are moved to the right or left.
A Great Tutorial http://www.inf.ufsc.br/~otuyama/eng/stereogram/basic/index.html How to make your own autostereograms…
Sir Charles Wheatstone, Patented First Stereoscope (1838) • A Wheatsone stereoscope (from the Greek for "solid viewing") uses mirrors to reflect disparate drawings into each eye. • Your eyes will blend the two views into one and the brain perceives it in three dimensions, the same as normal vision.
David Brewster, "Improved" Upon The Stereoscope (1849) • Stereo pictures, instead of being drawn, can be taken by means of a camera with two lenses. This provides two separate pictures 2.5 inches apart, about the distance between the eyes.
David Brewster, "Improved" Upon The Stereoscope (1849) Although the pictures appear the same, they are not. When looked at in a Brewster viewer, which has prismatic lenses, an illusion is created of a real scene lying in depth directly in front of the observer.
J.C. D'Almeida, An Early Anaglyph Projection Technique (1856) • D'Almeida gave a demonstration at the Academie des Sciences in which two stereoscopic images were projected on a screen in rapidly alternating succession through red and green colored lantern slides. • The audience would view the screen through spectacles fitted with red and green lenses.
J.C. D'Almeida, An Early Anaglyph Projection Technique (1856) • The green image could only be seen through the green lens, and the red image only through the red lens. • This would effectively send two slightly different images of the same scene to the brain of the viewer, where they would be combined to form a three-dimensional image. • This was NOT a movie, just one image projected, projected again and again.
Ducos du Haron, Refined the Anaglyph Projection Technique (~1890) • Ducos du Hauron developed an anaglyph projection system in which two transparent stereoscopic views (one red and one blue) were superimposed on top of each other and projected onto a screen. • Again, through the utilization of glasses with different colored lenses, this time a blue and red one, the spectator saw a 3D scene. • (Again, NOT a movie)
C. Grivolas, Invented First "Moving Picture" Stereoscope (1897) • By the end of the 19th Century, "moving pictures" had arrived... • ...so Grivolas figured out how to adapt anaglyph photography techniques to a specialized camera. • This camera exposed two reels of film at the same time, through two lenses spaced about 2.5 inches apart (remember, the distance between human eyes).
C. Grivolas, Invented First "Moving Picture" Stereoscope (1897) • The resulting prints were then projected simultaneously on to the same screen by two interlinked projectors, with one lens having a red filter and the other a blue one. The audience would don red and blue lensed glasses, and they would be able to see a three dimensional moving picture (Gasp!)
Further Improvements... • Harry K. Fairall- Produced the first feature length 3D film (The Power of Love) using anaglyph technology. • William Van Doren Kelley- Produced a short film (Movies of the Future) using what he called the Plasticon anaglyph process, with film coated on both sides, one side green, the other red.
Modernized Anaglyph Glasses • Anaglyph glassesuse two different color lenses to filter the images you look at on a screen. • The two most common colors used are red and blue (though red and cyan, or red and green, like in the back of our textbook, work as well).
Anaglyph Glasses • If you were to look at an anaglyph-type image (like the one below)without these glasses, you would actually see two sets of images that are slightly differentfrom each other. • One will have a blue tint to it, and the other will have a red tint.
Anaglyph Glasses • Only the Red-Colored Image gets through the Red Filter, and thus into the Left Eye. • Only theBlue-Colored Image gets through the Blue Filter, and thus into theRight Eye.
Anaglyph Glasses • Because each eye can only see one set of the different colored images, your brain interprets this to mean that both eyes are looking at the same object. But your eyes are converging on a point that's different from the original image’s focal point. That's what creates the illusion of depth.
Anaglyph Glasses Pros: • The glasses are pretty cheap, costing less than a dollar. Cons: • Because of the color tinted glasses, the images are never their true color, and takes away some of the “reality” of the experience • The quality of the 3D image is quite poor, resulting in feelings of nausea and headaches in a large proportion of viewers.
Laurens Hammond and William F. Cassidy, The Teleview Process (1922) • The Teleview Process required two reels of film to be exposed through lenses approximately 2 ½ inches apart. The two resulting prints were run simultaneously through two projectors that were electronically linked so that they would remain synchronized throughout the performance. • One print, however, would always be one frame behind the other; this would produce alternating left and right images on the screen (a technique used before by D'Almeida)
Laurens Hammond and William F. Cassidy, The Teleview Process (1922) • Each member of the audience would be seated behind his own ‘televiewer’ - the heart of the system. This mechanical viewing device contained a rotating shutter, driven by an electric motor running in sync with the projectors, and turning at about 1500 rpm. • The shutter would block the left eye view of the spectator when the right eye image was on the screen, and vice versa.
Laurens Hammond and William F. Cassidy, TheTeleview Process (1922) • Unfortunately, the Teleview Process was too uncomfortable and costly to catch on in a major way, so it was left by the wayside... Until 3D home-viewing systemscame around!
The Modernized Teleview Process:Active-Shutter Glasses These glasses are battery-operated, and use both active–shutter, and liquid crystal display (LCD) technology. They are synched with your movie playing device via Bluetooth, radio, or infrared technology.
Active-Shutter Glasses Active-Shutter Technology: the two lenses open and close in extremely rapid alternation while the screen displays the appropriate left-eye and right-eye images.
Active-Shutter Glasses Liquid Crystal Display (LCD) Technology: The LCD lenses in the glasses alternate between being transparent and opaque as the images alternate on the screen. The crystals respond to the electronic signals they receive from the movie viewing device.
Active-Shutter Glasses The result is that the left eye sees only the intended left view of the image, and the right eye sees the intended right view. This happens so fast that your brain blends the images together into a single, stereoscopic image.
Active-Shutter Glasses Pros: • Robust, mature technology (Sony and Panasonic are already backing it). • Reduced eye fatigue Cons: • Glasses are expensive and require batteries (it would suck to run out of batteries mid-way through a movie watching, and buying enough to have a pair for any friends who wanted to come over and watch a movie could bankrupt you). • The videos can be dim as the glasses reduce the brightness of the image.
Edwin H. Land, Polarized Filters (1932) • In addition to being the founder of the Polaroid camera and company, Land also developed polarized filters for full-color stereoscopic movie viewing.
ModernizedPolarized Glasses These glasses have two lenses that have been polarized to be orthogonal (set perpendicularly at 90-degree angles) to one another.
Polarized Glasses Because each filter passes only the light that is similarly polarized and blocks the orthogonally polarized light, each eye sees only the image intended for it. The brain then puts these images together to create a three-dimensional effect.