Coming soon to the very small screen


(The first half of this movie is cross-view; the second half is the same movie in parallel format.) 

Portable 3-D ‘theaters’

The breakthrough that makes the pocket stereo viewer possible is the new ‘retina” screen on the iPhone 4 and the iPod touch 4th generation, both of which have a pixel density of 331 per inch.   This density makes it possible to tolerate some magnification without breaking down into obvious pixellation.

When the screen is divided in half by software and the left-right movie “panes” are conveyed to the eyes through lenses, the opening up of depth and space and the appearance of solidity--the essence of the stereoscopic experience--happens as a kind of revelation.  The screen seems to disappear or become transparent as one’s attention enters the space and wraps around the objects in the scene.  So far, this is not much different from any 3-D experience. 

But the side-by-side, two-lensed video viewer offers some advantages over other methods of conveying stereo movies.  First, putting a dark enclosure around the screen and separating the two views by a curtain or septum turns the viewer into a private screening room.  Psychologically, one seems to be alone in the middle row of a theater with a good-size screen, not a skimpy multiplex.  Each of the image pairs on an iPhone or other small player is actually about the size of a 35mm slide, more than twice as large as the old Viewmaster, Second, without the interference from polarized or red-blue glasses or the corresponding filters on a projector, and without the sensory blast from the big-screen theater experience, the finer points of stereoscopic viewing can be appreciated in detail. 

Some examples:


     1. With all stereoscopic media, and more clearly with the binocular “mainlining” of the two-lensed video stereoscope, when the two images are taken in by the two eyes separately they arrive at the visual cortex just as if they were separate real-life signals from the two retinas, but they are isolated views of a kind not found in real-world vision, with all its oscillations and crosstalk.  When the brain combines the two isolated stereoscope images, the depth information can be intensely focused on, so the perception of space is heightened into a kind of ultrastereo, very similar to the experience of listening through stereo headphones.

      2. The stereoscope, again with its purer path to the eye, makes another effect of binocular vision more obvious: the sharpening, detail-heightening and aesthetic improvement of 3-D images over 2-D.  This can be tested by pausing any of the movies on this site and comparing the single left or right still-frames with a fused freeview, parallel or cross-eyed. 

     The investigation of this effect has a curious history, starting with the observation in 1877 by A. L. Austin of New Zealand that, while tinkering with his stereoscope, portraits of “two different persons’ faces, . . . being about the same sizes, and looking in the same direction, and placing them in a stereoscope, the faces blend into one in a most remarkable manner, producing in the case of some ladies’ portraits, in every instance, a decided improvement in beauty.”  

    In a 1976 Scientific American article* on this subject, John Ross concludes that there is “some critical faculty in the visual system that is capable of making decisions and of rejecting information, apparently on aesthetic grounds.”  Operating beneath our conscious awareness, this faculty seems to gladly throw out fuzzy noise or unfuseable detail because it can’t be used to construct a better, sharper binocular picture.  (A demonstration of this effect is in the video above:  two pencil drawings of different faces are reproduced from the article and displayed as a side-by-side pair; what you see in the fused view is an improved, pleasant face made out of the two not-so-great faces.) 

     3. The video stereoscope may counter the tendency of new 3-D filmmakers to throw images at the audience or into the theater space, though this of course will only be proved in practice.  The big screen and the amassed audience seem to bring with them the expectation of spectacle.  The small screen and the solitary user of the pocket theater may demand a more intimate and contained thrill-factor that emphasizes the individual’s center of awareness and how it can be drawn in to the picture.   There is always a certain “psycho-gravitational” pull inherent in a good 3-D picture that may demand more emphasis in the small-screen theater.

A great leap inward

It has been an article of faith among stereo still photographers that the very act of binocular fusion is pleasurable in itself, for reasons only hinted at above.  This explains why there have been dozens of stereo clubs meeting around the world for many years for the benefit of people hooked on fusion and depth.  As the full implications of digital 3-D video settle in and individuals begin making their own movies, much stereo experience and thought will be directed toward finding a new grammar and syntax of deep moving pictures. 

This much can be said in a theoretical way:  Since our binocular visual system derives from ancestors of the primates who lived high up in trees, some gliding and some swinging at speed from branch to branch, it may be that moving through space and picking out moving, complex detail will turn out to be the most compelling kinds of 3-D motion pictures for the small screen, or for that matter, maybe the big screen as well.  Fast depth-in-motion vision not only allowed our ancestors to move around by death-defying, accurate branch grabs, but also, no doubt, a great deal of pleasurable thrill-seeking as a normal part of life.  We have lost some awareness of all this by our exile onto the ground, but it explains our attraction to flying, skiing and all manner of fast ways of moving through space, or catching and hitting things that are moving fast through space. 

In the best 3-D motion pictures, we seem to enter into the worlds that open before us, even as the pictures enter into us.  Branches waving in the wind seem oddly inviting.  Flapping wings beckon us to follow.  Shape, richness of surface detail and structure become the primary picture elements, replacing the 2-D parameters of light-and-shadow, figure-ground, and linear perspective.  For those interested, more on the subject of this medium’s “message” is here.

This is the place to point out that the 5-10% of us who do not see stereoptically can still deeply appreciate the world by using distance, relative motion, light-and-shadow and other cues to perceive depth.  (Rembrandt may have been one of these; he apparently used his strabismus to great advantage to perceive and portray light, depth and surface detail.)  Those who have two working and tracking eyes but lack fusion skills may actually improve their depth perception by practicing with the video stereoscope.  Will they discover fusion by using depth cues that stereo people are not aware of?  Will we all learn to perceive more deeply?  We shall see.  

What’s next?

*”The Resources of Binocular Perception,” Scientific American, Vol. 234, No. 3, March, 1976, pp. 80-86.