February 6: Stereopsis is a subtle thing, a feeling, not just a vision.
Today in 1802 Charles Wheatstone was born in England. He became a prodigious scientist and inventor in music, cryptography, electricity and telegraphy.
Most important to photographers is his contribution to knowledge about human binocular vision delivered in his Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision on June 21, 1838 when he was Professor of Experimental Philosophy in King’s College, London.
His paper was accompanied by his invention, the first stereoscope, though because he made it in 1838, his device used geometric line drawings since it appeared in the same year as daguerreotypes and talbotypes, were announced.
His discovery has been invaluable in fields as diverse as cartography and medical imaging, but it has also seen several revivals in the visual arts including photography and cinema, and even in painting, and now of course in virtual imaging, in the current fad for 3D headsets, but note that 3D TV has recently followed the 3D movie into the bin. Even after the 2010 success of Avatar there are now 3D TVs being made as the last two TV makers to build 3D functionality into their sets, LG and Sony, will not build any new sets this year that can show 3D movies and TV shows.
The reason? Some people don’t get it. Up to 12% of people cannot use their binocular vision, are stereo-blind, or have monocular vision and lack depth perception because of disorders that prevent the eyes focusing and/or aligning correctly (e.g. amblyopia, strabismus, optic nerve hypoplasia) or simply from loss of vision in one eye.
Stereopsis is a subtle thing. Cinematographers may want to direct your attention to a particular point on the screen, which is easy to achieve by focussing on that point with a conventional camera with one lens. 3D requires all-over focus so that effect is not able to be used easily with the two lenses required for binocular filming so it s the viewer who selects the point of focus. It is problematic to try to duplicate our eyes’ ability to rotate to bring a certain point into three-dimensional relief.
As a child, a visit to my grandparents was a respite from home (likewise no doubt for my parents). A highlight amid the tame entertainments proffered by the elders was to sit in the garden in autumnal Easter sunlight, under the weary fruit trees, at a wicker table scattered with stereo cards.
The viewer was a curious artifact, like a scientific instrument so old that it had become a toy. Its lenses, thick and greenish like grandfather’s reading glasses, were mounted in shellacked plywood and sheathed in an embossed zinc eyeshade lined with blue baize. Odours of old books, sweat and brilliantine dwelt in its fabric.
The cards themselves, with bowed backs like old gents, were shuffled and selected. A magnified view of my fingers and a card appeared inside the hood as they placed it clumsily, by feel, between wire brackets on a rather wonky wooden crossbar. Some pulling and shoving at the bracket brought focus and teamed up the reluctant, sliding images, which suddenly inflated themselves into pyramids and camels. Desert sands unrolled, and blocks of sandstone stacked themselves into a hasty semblance of mighty ruination. The bleaching desert sun Linotyped hieroglyphs across their faces and we were in Egypt, in The Holy Land, a hundred or two thousand years ago.
All was as still as pillars of salt, and only our eyes could move. Lettering which announced “The Great Pyramids” or “Jerusalem” hovered redundantly outside the image, doing nothing to explain the mesmerising spell, only underlining the threshold over which one could never crawl no matter how great the nostalgia, because this was another land. It made you dream. From then on, I have peered around the corners in every photograph I encounter.
Stereoscopy fragments one image into two images, which look on first glance to be the same since differences in viewpoint are only slight. The stereoscopic image does not exist in the fragments and their latent illusionism does not appear until the observer themself ‘joins’ them. Then, just as Wheatstone predicted, instead of seeing the optical disparity between the two images, what is experienced instead is a feeling (yes a ‘feeling’ not just a vision) of three-dimensionality, like proprioception. Thus, the stereoscope successively produces and eliminates the difference between two optical images. This in turn produces an “effect” or “experience” of three-dimensionality that adds the difference between the two representational images by deleting the individual images!
However, it is cardboard scenery, containing only an expectation of space and devoid of the skeleton dimension of time. There is a disappointing ‘tunnel’ effect because the field of view feels unnaturally constrained. There is no correspondence between depth and focus, because everything remains equally sharp as our eyes penetrate the scene. Certainly, areas may be out of focus in the camera images presented to the eyes if the photographer has used shallow depth of field or objects near the camera intrude into the frame. The effect that we are used to in real seeing, of focus changing along with our gaze as it moves from foreground to background, then does not occur. The process also renders voluminous forms as cardboard cutouts, reducing the effect of binocular vision to two-dimensional planes receding in three-dimensional space.
Clearly there are limits to the stereoscopic illusion of being ‘in the image’. What is missing in the information provided to us may be the links our mind makes with other signals from our body about the space we are seeing. Such motion is absent in a stereo image. Part of this feedback is the muscular sensations we receive as our eyes converge on parts of the scene. In fact, our whole biology, our socketed eyes, mobile head, articulated body, participates to satisfy any curiosity about the space in which we are.
A 3D film produces exaggerations whose melodramatic effects may be exploited in horror movies but are artificial and ‘disembodying’. Forced upon us is the camera’s vision of the space that removes the feedback of our movements, even those limited to the subtle swaying of the head. These test what we see, especially with regard to minor relief on the surfaces of objects which the disparity between the two ocular images fails to render.
A stereo pair is produced with two lenses whose optical axes are parallel and it is a condition of their success in conveying a three dimensional impression that the viewers eyes are similarly parallel in their direction of gaze. The representation of close objects is not possible. They force the viewer into cross-eyed contortions because convergent vision is not accommodated by the technology, though it is a natural part of our three dimensional vision.
Even though they fascinate me, my experience of viewing and producing stereo photographs made me aware of their limitations. When I was a teenager, I made my first stereo photographs with a 35 mm camera, by swapping the viewfinder from right eye to left eye between shots, keeping the camera level and my head still. Then I printed the small images side by side for viewing in the stereoscope which I constructed using the edges of identical magnifying glasses.
This experience has been enough to convince me that photography might be better suited to dissecting binocular vision than to reproducing it. It is clear also that the artistic use of stereo still imaging is limited. Despite some quite serious efforts, three dimensional images tend to remain a curiosity, a gimmick. In 1974, Roger Ferragallo (*1923) issued a manifesto, later accepted for publication in Leonardo, which called for a reconsideration of the metaphoric and poetic potential of stereo images:
Painting is reborn. Enter the new awareness of Stereo Space and a New Aesthetics …….The centuries long conquest of plastic forms within a monoscopic pictorial space is ended……..A new era lies ahead for the visual arts…….The living third dimensional space-field awaits its birth. It asks nothing more than the trance-like stare of the middle eye to invoke Cyclops to waken from his 35,000 year sleep. This primeval giants [sic] reward will be the sudden revelation and witness to the dematerialization of the picture surface into an aesthetics of pure space where visible forms will materialize and release themselves—forms that are suspended, floating, hovering, poised, driving backward and forward, near enough to touch and far enough away to escape into the void. So now enter a new aesthetic empathy, meditation, subjective intensity and an unparalleled form-space generation and communication. All of this exciting injunction could have been declared 134 years ago had it not been for the invention of photography.
Ferragallo’s manifesto calls for the a world prepared to accustom itself to view dimensional illusions with the naked eye: “Stereoscopic aesthetics will be an arena that will see the plastic forms of the past 100 years fusing into staggering arrays of recombinations of familiar and unfamiliar forms, new synthesis, shimmering-lustrous colour fields; all existing in air—a space without a canvas base, paper base or physical carrier whatever.”
His manifesto would seem to have fallen into the hands of the wrong people. A major manifestation was the proliferation of “Magic Eye” posters and books of the 1990s. Such illusions in part employ an effect where elements of a regular pattern can be merged by the eye to produce a duplication of the pattern, which stands forward or recedes behind the real surface.
The ‘wallpaper’ illusion was noted first from his own observations by Blagden 1813, repeated by Brewster 1844, both significantly during the industrial revolution when mass-produced regular patterns could be generated with ease. Ferragallo’s writing calls for a revival of the effect, and an audience with the patience to conjure it. Though the contemporary version has enjoyed a popular following, it has rarely found a place in mainstream galleries nor attracted much serious critical evaluation as an art form.
According to Professor Takanori Okoshi (大越孝敬, *1932) the first attempt at a stereoscopic drawing was a technique devised by Giovanni Battista della Porta (1535–1615) around the year 1600. Surrealists experimented with stereoscopy. Rene Magritte‘s (1898–1967) “Man with a Newspaper” (The Tate Gallery, London, England, 1928) consists of four simply painted scenes in his deadpan style, which seem to be indistinguishable apart from the disappearance of the man of the title. They were based on an illustration in a popular health manual. They can be read as a narrative, but slight changes of perspective between the four panels add to the disquieting effect, especially when viewed in 3D. Characteristic of Magritte and his Belgian Surrealist colleagues is this quiet subversion.
Salvador Dali (1904–1989) experimented with stereo images, and later with holography, possibly because of seeing some molecular graphics in stereo, since he includes DNA molecules in some of his photograph-assisted stereo paintings. However, his main motivation, a desire to produce an ‘hallucinatory realism’, emphasises the mirage-like quality that the moment of fusion in viewing stereo images certainly does have.
Bela Julesz (1928–2003), State of New Jersey Professor of Psychology and Director of Rutgers University’s Laboratory of Vision Research, and a pioneer in random dot stereographs, describes his own interactions and influence on Dali (Julesz, 1994). The Salvador Dali Museum in Figueras, near Barcelona has on exhibition some examples (quite small) that are set up for direct viewing with a pair of mirrors at 90 degrees. Larger paintings are side-by-side and meant to be viewed (without optical aid) from across the room.
In 1984, James Turrell (*1943) exhibited, at Karl Bornstein Gallery, 1.3 metre square aerial stereo pairs of his massive Roden Crater earthwork to be viewed in an enlarged Wheatstone stereograph. Turrell, a pilot, took the photographs with an old army aerial camera. Distances between exposures of sixty-one metres exaggerated the ‘interocular’ distance and thus the three-dimensional sense of depth in the image, miniaturizing the crater.
Turrell’s use of stereo photography was a logical extension of, and publicity for, his adaptation of the crater to create a perceptual phenomenon, “celestial vaulting,” in which the sky appears to be a huge, domed ceiling.
American-born Australian David Stephenson (*1955) exhibited stereo components of his Domes series as “Virtual Dome” at Robert Lindsay Gallery in Melbourne (2000) in a Wheatstone viewer. The Domes project was begun in 1993 during an Australia Council residency in Italy, and he has returned several times to build a collection of hundreds of images of cupolas from buildings all over Europe.
None of the above examples is part of a larger movement as envisaged by Ferragallo in his manifesto, though he wrote later of his discovery that some contemporaries were thinking along the same lines. These include Edward Trent in England who was almost simultaneously rediscovering and developing ‘wallpaper’ stereography, also Oscar Fischinger (1900–1967) who created several large cross-vision free view paintings in 1948 and early 1950’s.
Significantly, Ferragallo was unaware of Dali’s stereo work of the seventies, but discovered that Swiss painter/sculptor Alphons Schilling (1934–2013) who showed Binocularis at Galerie Ariadne, had commenced his stereoscopic drawings and paintings in 1973. His experience of feeling he was at the vanguard of stereo imaging for artistic purpose is a good illustration that applications of stereo imaging in art remained relatively isolated and obscure up to the advent of virtual reality headsets.
Schilling produced a number of viewing machines that he called Gazelle that reversed stereo vision of real objects, environments and installations. These could be regarded as a means of stepping between the stereo camera and the stereogram, disrupting and inverting the experience of 3D vision.
Double vision is the basis of stereoscopy, and I have used it in my own investigations. This brief history, and my personal experience, have confirmed for me that stereo images as such could not advance my ideas about the differences between human and camera vision.
This is because because stereoscopy emulates binocular sight by making the surface of the photograph as close to transparent as possible;
A stereoscope is an instrument which makes surfaces look solid. All pictures in which perspective and light and shade are properly managed, have more or less of the effect of solidity; but by this instrument that effect is so heightened as to produce an appearance of reality which cheats the senses with its seeming truth
So wrote Oliver Wendell Holmes Snr. (1809–1894) in what is still the most vivid explanation of the medium (1859). He outlines an experiment in which he proves that we see objects in the stereoscope life-size, confirming that it is only the uncanny stillness; “a stillness as complete as that of the tumbling tide of Niagara as we see it self-pictured.”, that reminds us of their origin in the camera. This is not a medium that is self-referential.
Certainly anamorphic art, like that of Bernard Voita (*1960), Calum Colvin (*1961) et al. could well employ stereoscopy as a revelatory apparatus for viewing their ambiguous imagery. The view through one eye would set up the illusion, while sighting with both eyes would expose it by revealing the ‘real’ space. However, this would only reinforce the realism of the stereo image, while the intention of my work is to revise stereo imagery itself to preserve the viewer’s conciousness of double vision and expose its effect by arresting it before it could become binocular vision. For this reason some 16 years ago I evoked paired sight in the composition of my exhibited works Compass (2002), In the strange form of a stave (2004) and Before me the dazzling apparition (2004), as a key to their purpose. Each of these contains two views of the one location and presents them side by side.
In Compass, the earlier work, right-angle views of one point in the landscape have been taken and montaged next to each other. The paired images themselves contain rotations set up by three superimposed converging angles of view in each. The rotations of the coupled images oppose each other, so that too would repel the conjoining that is expected of a stereoscope pair. These dis-locations of the same site reproduces the sensation of disorientation, or fear of being lost, amidst staves of spindly coppiced trunks in the ‘no-place’ of such forests that have regrown repeatedly in this old goldfields landscape. The trees splinter the glaring midday sunlight and crowd out every horizon so that forward or back seem the same.
These images of an abandoned mine tunnel, Before me the dazzling apparition from 2004, effectively form a panorama of views out of the entrance and toward the interior, each is an orb in surrounding blackness, together evoking more the sockets of a deathshead than a stereo pair, though the semblance of dual images on a stereo card.
I repeatedly photographed a mine shaft deep in a pineforest, making several in-camera montages of binocular takes, changing the point of coincidence in each. From these I selected two for In the strange form of a stave (2004), separating the eye-shaped forms of the shaft with a third image in which the rotted stump of a large redgum, felled for the planting of the pines, protrudes from the surface. This is the most intentionally visage-like of the vortex images, for the purpose of reflecting the double imaging of our two eyes back to the viewer.
The spell of stereo images underlines the limitations of stereoscopy as an art form.