Stereoscopy: Where Did It Come From? Where Will It Lead?

by Harold A. Layer,
updated version published originally in: EXPOSURE: 17:3 Fall 1979, pgs 34-48
and presented as "The Binocular Image---Its Evolving Significance for Photography"
at the 1979 National Conference of the Society for Photographic Education, Fort Worth, Texas.


c.1900 stereograph
Stereograph c.1895. May be viewed stereoscopically. Not marked: unknown location and unknown photographer. Early example of split-image stereoscopic space synthesis.
c.1900 stereograph
Stereograph dated 1898. May be viewed stereoscopically. This example illustrates that early stereographers were well aware of the creative value of manipulating stereoscopic space. The two stereo pairs below are close-ups of the strange double mirrors placed on the paintings in the scene to enhance 3D effects.

c.1900 stereograph . . . c.1900 stereograph


(© 1970, H. Layer, all rights reserved)

The stereo camera, in spite of its antiquity, is still in its infancy as a serious tool for making the most revolutionary photo image of all--the binocular image--the product of a new pictorial medium without precedent in the entire history of art. This paper will survey the close evolution of consciousness, art, and image-making, converging process that led inexorably to the binocular image. Stereoscopy and holography are proposed as techniques for resolving the illusionistic impasse faced by photography and the other pictorial arts.

Monoscopy

Many writers have considered that the art of an age reflects the nature of consciousness of those who make and use its indigenous images. Beginning with the earliest visual records--supported by recent studies of the untutored drawings of young children--we find an intuitive acceptance of pictures that lack accuracy, or even detail, as representations of reality. It seems universal that a few distinguishing features of form, some simple monocular cues of space, have met the basic needs of visual communication since the dawn of man.

An examination of prehistoric European cave paintings reveals that, in formal terms, their depiction of space bears little relation to modern methods of depiction. There is little organization of spatial direction. Subjects are jumbled and superimposed without relation to each other. Concepts of inside and outside, up and down, large and small, are not always evident in the worK. Thus, it has been concluded that the cave painter's consciousness may have been very different from our own.

The spatial characteristics of ancient Greek and Roman art are also thought to reflect something about the nature of their culture and thinking. Mueller has commented on the Greeks' "abstraction barrier" derived from the linear, tactile level of their visual arts, limits that are also apparent in their exactly codified, monophonic music and their Euclidean mathematics. Certainly, many Greco-Roman artists had abilities in draughtsmanship comparable to those of renaissance artists, but they appear to have lacked the ability or the desire to compose the spatial structure of their drawings. Friedenwald has noted that the Chinese, too, did not organize objects spatially in a single composition, and one device they used to overcome this difficulty was to "invite the viewer to wander in a space of almost endless mists."

The manner of portraying pictorial space from the ancient Greeks to the renaissance revealed a change in the western concept of infinity, according to Panofsky. This refers to an interesting theory of how the evolution of portraying space occurred. If one examines paintings from 500 A.D. to 1400 A.D. in sequence, one can see space gradually extending outward from the nearby central subject of the work. White considers this evolution as the freeing of pictorial space from the subject. Eventually the process was complete, and with the discovery of the laws of perspective, space itself was composed all the way to infinity, followed by the containment of objects in this space which were drawn carefully in accordance with its rules. Several precursors to the laws of perspective may be found from the 12th century on, but certainly a major event, one that many historians feel signaled a new visual consciousness, was the publication of Alberti's perspective rules in 1435 A.D.

Perspective is defined as the locus of all points of intersection of straight lines through the picture plane from a fixed viewpoint (the station point) to the object. The perspective drawing is considered a representation or projection of the object.

Important determinants of a perspective drawing are the viewpoint's position, the picture plane's position, and the viewpoint's distance from the object. The latter (called the principal distance) affects only the scale of the perspective, not its geometrical proportions. One of the perceptual qualities of perspective drawings that can be used by both the artist and the photographer is "displacement of viewpoint." The changes in perspective that result from using different focal-length lenses are a common means of achieving this control.

The key to the power of perspective as a rational substitute for the intuitive comprehension of space is its obedience to the laws of the projected image. As White states, perspective enables the artist to recreate reality in a way that convinces the eye as well as the mind.

But the hold on the artist of the a priori laws of perspective was finally broken, ironically, by the quintessence perspective image, the photograph--ironically, because the photograph obeyed the laws of perspective blindly, automatically, and perfectly. Thus, many artists began exploring space with other, more exotic, laws of pictorial organization. The latter half of the nineteenth century and the first decades of the twentieth century saw the rupture of traditional modes of painting and a retreat from what Ivins has called "the rationalization of sight." Once again, a new visual consciousness seemed to be evolving.

The impressionists were among the first groups of artists to break away from the dictates of perspective and the imitative function of art. They recognized that space on the canvas was illusory; thus, they strove to express inner rather than outer reality, the ideal rather than the real. This dissatisfaction with the canvas as a "window" and awareness of the gap between reality and illusion became more acute with Cezanne and, later, the cubists. Their approach is central to my argument: namely, that the binocular image is, at the same time, both a solution to the limitations of a flat photographic print and a problem for traditional definitions of photographic illusion.

Cezanne rejected classical perspective and strived to increase the spatial impact of his paintings in other ways, such as by transforming objects and spaces into the basic elements of cubes, spheres, and cones. It has been noted by one critic that Cezanne's pictures convey a great sense of volume in the foreground and middle ground, but the background is flat like the backdrop of a theater set.

Richardson wrote that "the achievements of Cezanne and the non-Euclidean geometers are similar. Both showed that alternative articulations of space are as satisfying structurally as the old a priori articulations." The cubists also made a self-conscious attempt to transcend the space and time limits of painting. Their work included successive and/or compounded changes in the subject itself--either movement of the subject or changes in the observer's viewpoint. The former technique added a fourth dimension to painting--time. The latter technique increased the total spatial possibilities of a subject by superimposing many different viewpoints. In fact, this new organization of simultaneous spaces was the most characteristic and important stylistic trait of the early cubists.

But, as cubism evolved, the artist's attention shifted away from the end to the means, from the subject to the paint. This culminated in the concreteness of the collage and the relief construction. It is interesting to note that late in the cubist movement, Picasso and others began to create a subject with their collages. Gris commented that they began with an abstraction as an idea and then attempted to see a subject through the abstraction.

After cubism, the evolution away from a simple spatial reproduction of a subject continued. Piet Mondrian wrote that, "Reality is form and space. Nature reveals forms in space...Art has to determine space as well as form and to create the equivalence of these two factors...The expression of pure reality can only be established through pure plastics (italics are Mondrian's)." He recommended that natural forms be reduced to "elements" of form, and natural color to "primary" color. Mondrian's unique paintings are a consequence of his theories. We can only speculate on how he might have reduced natural binocular space to pure stereo space.

What is form? What is the relationship of form to the subject? These are still vital issues today. Pinchbeck felt that the breakdown of form in abstract expressionism reflected a new collapse of values in society. In addition, he wrote that "the continuation of painting and sculpture conceived as separate mediums is obsolete and that the need is for a total 16 form in three dimensional space."

The continuation of these philosophical concerns in recent times is seen in Vasarely's five developmental stages of abstract art, the final one being the abandonment of the picture plane as a final goal because of a need for the superior dimensions: space, movement, and time.

In the last decade many art critics have claimed that abstract art, which at first liberated the artist from imitating three-dimensional space on a two-dimensional surface, has degenerated into a variety of obtuse academic camps. One recent reaction against all of this, of course, is neo-realism. But what seems to have been ignored is an available technology for creating real binocular spaces in a pictorial manner. Stereoscopic photography allows the construction or reproduction of real spaces pictorially without the limitations of a flat picture surface. What I mean by "real" is that the reconstructed image exists only in the brain of the viewer, not in the two drawings or photographs that serve only as stencils for the binocular image.

And I use the word "pictorial" because the process and product of stereo photography are closer to traditional photography and painting than they are to sculpture and architecture--two other arts that invoke visual space. Thus, for the first time since the artist began drawing on walls, with stereoscopy his picturing process was limited no longer to two dimensions.

Photography, because of its dependence on the camera obscura as a tool, is mechanically locked to the dictates of perspective and single-point projection for its expression of space. Lenses of different focal lengths change the gradient of perspective within a given picture space, but the creative possibilities of these lenses do not seem to have been appreciated until recently. Thus, most early photographic art did not manipulate the spatial qualities that it recorded, but was often documentary in theme, whether its style was realistic or impressionistic.

Objective Space

Profound changes in our awareness of space and time are occurring. Philosophers and scientists are examining anew the boundaries between interior and exterior realities. The result is that our understanding of ourselves, our language, and even our perceptions are changing dramatically. At this time, the photographer is beginning to explore the beauty, the terror, the new meaning, of space itself as a subject of importance and as a malleable material for creative work. As one writer has expressed, "New sensations always give rise to new arts."

One of the greatest potentialities of our new tools of communications--described by Marshall McLuhan as extensions of our senses--is to make visible those existences and experiences which cannot be perceived directly. Ivins has noted that science has advanced only as man has developed methods to translate those phenomena known only by touch, taste, smell, or sound to his sense of vision, because vision allows this phenomenon to be more easily symbolized and subjected to rational thought and analysis.

The dependency of our intellectual life and structure of our western logic is more related to our sensory experience than we have realized. McLuhan has pointed out that any change in perception brought on by technology sets up new ratios or proportions among our senses--such as between seeing and touching. In fact, it has been hypothesized that the conceptual limitations of ancient Greek mathematics are a result of the overly-developed tactile aspect of Greek life.

The nature of physical space is a major philosophical issue. Two basic, opposing conceptions are:

1. Space is simply a quality of objects and energy fields--empty space does not exist.

2. Space is a container of objects and energy.

Einstein pointed out that the latter conception raises space to a position superior to that of the material world. The superiority of space to materiality--or indeed its separateness--may be an unresolvable question, but an interesting one nonetheless.

According to Guggenheimer, modern science has advanced new motilities and spatialities which will lead to new conceptions of ourselves and our universe. But, however "intellectual" its beginning has been, the scientific approach to the issue of space opens new horizons for the artist's vision. Just when the twentieth-century photographer begins to see his work as a physical, aesthetic object in its own right--rather than simply a conveyor of a spatial illusion--he will have to consider space not as entity experienced alone, but as an interval between objects, just as time is experienced as an interval between events.

Subjective Space

New problems occur when we shift our focus from the nature of space to our perception of it. The consensus of psychologists seems to be that our visual perception of object form and volume, and the spaces between objects, are simply psychic sensations--no more real than the red color that we see when looking at a red object.

These sensations exist in our heads and not out in the world, although they are derived or cued in a predictable fashion from energy changes in the world. Thus, I will never know whether the red color that I see is qualitatively the same as the red you see even though we are consistent in our behavior when tested. In a similar manner, my impression of physical space may be quite different from yours--even inverted phenomenologically, but I will be able to respond to my sensation of spatiality with the same precision and knowledge that you can. Again, no outside observer can reach inside our heads to obtain a sample of our psychic differences. There seems to be no way of framing a question or implanting an electrode to reveal the nature of a sensation.

Our perception of space is derived from a variety of energy forces received by several sensory organs and interpreted in many ways. We experience tactile space, monaural space, binaural space, monoscopic space, and stereoscopic space. Each has its own unique qualities, and each can support or counter the other. In addition, our memories of past objects and spaces interact with on-going experiences and with anticipations of the future.

While we have learned to coordinate the sensory input from touching, hearing, and seeing, our eyes seem to operate independently. Parker has noted that this is because only the eye deals with connected spaces. To the sighted man, all is connected. However, in the experience of the blind, all things are unconnected and sudden. Senden has found that the congenitally blind have no a priori awareness of space. They have no spatial idea of the positions of objects in a room. Objects are not shapes, but tactual sequences. The environment of the blind is a network of temporal relationships based on ordered succession among tactual and auditory perceptions.

Senden discovered that recently sighted patients (after cataract surgery, for example) orient themselves visually only after they give up older mental constructions of their environment. The schema that fit the simultaneous spatiality of vision and the linear, successive spatiality of touch were somehow irreconcilable. He reported the observation of a 13-year old blind patient who, upon gaining his sight, remarked that all objects seemed to "touch" his eyes simultaneously. In 1850, a 12-year old blind girl trying to understand the nature of vision said, "I admitted to myself that there was in fact a highly important difference between myself and other people; whereas I could make contact with them by touch and hearing, they were bound to me through an unknown sense, which entirely surrounded me even from a distance, followed me about, penetrated through me and somehow held me in its power from morning to night."

Thus, profound differences can be found, not only in the way in which our various senses respond to the energy fields of our environment, but also in the interpretations, the psychic models, we create to represent the spaces through which we move. Even in a single sense modality, vision, two profoundly different impressions of space are seen: monoscopic space and stereoscopic space.

Monocular Vision

Monoscopic space is one-eyed space. Any impression of depth that can be acquired must be derived from perceptual cues available to either eye by itself. The important monocular cues are:

texture gradient
object size
height in the visual field
linear perspective
aerial perspective
object overlay
accommodation
motion parallax

Monocular cues have been known and studied for many years--usually by the artist long before the scientist. Object overlay was first described by Helmholtz in the 1850s, but has been used consistently by painters for at least 20,000 years. Motion parallax is a feature of some eighteenth century toys, but was first identified as a depth cue by Sir Charles Wheatstone. Linear perspective is one of the most powerful monocular depth cues since it combines in an orderly, mathematical framework the cues of size, texture, and height. Its power is evidenced by the fact that even an obviously false, but well constructed, perspective will dominate over other depth cues (including the binocular depth cue, stereopsis) and often controls a viewer's judgment about an object or scene. It has been said that photography is the daughter of perspective because photography, the camera obscura, and perspective produce images that obey the same laws.

Monocular depth cues are well known to the photographer who manipulates them often, consciously or unconsciously, in his work. In fact, he often stresses specific cues in order to compensate for the fact that his forms are flat images on a flat surface, such as the photo print or the projection screen. One common example is backlighting, which has always been a popular technique used to separate the central subject from its background. But, as discussed, the profound limitations of one-eyed cues of depth have become a central philosophical Problem for the twentieth-century photographer and artist.

Binocular Vision

Nature did not grant us a second eye just for insurance. Nor does our second eye increase our sensitivity to low light levels. The nature of our two-eye vision, as well as the nature of our two-hemisphere brains, are great mysteries in biology. Binocular vision allows a new kind of space perception, stereopsis, but the full story of its role in the evolution of the mind has yet to be told.

Before discussing stereopsis, I want to examine three other attributes of binocular vision: rivalry, convergence, and disparity.

Rivalry.

Binocular rivalry is a unique phenomenon of tweed vision. It is not a perception of depth or space, yet it adds a richness to many subjects that is difficult to describe. The composite visual experience of two rival images is self-contradictory; it does not necessarily include depth, but can add a flashing, sometimes disturbing, sometimes beautiful quality to a subject.

One of the key applications of the rivalry cue is as an optical comparator of similar objects or images. Any minute differences are noted in a perception of flicker or oscillating relief. A star field photograph is displayed to the left eye, while a photograph taken one week later is displayed to the right eye. A rival pinpoint of light, which may be a new comet or supernova, is quickly discernible even in the midst of tens of thousands of stars.

An important attribute of rivalry is its role in conveying qualities of surface and texture, such as the sheen of bronze, the luster of chrome, and the brilliance of diamonds. Stereo vision allows a viewer to make a binocular comparison of any surface in order to separate its true appearance from the interference of reflected light. Although we are able, in one sense, to ignore the "noise" of a subject's illumination, we also include it, in another sense, in the totality, the total light radiation from an object with the result of less ambiguity--an attribute of rivalry of great value, for example, in portraying metallic pigments.

Convergence.

Eye convergence is tied normally to binocular parallax and image disparity and, thus, is very difficult to isolate as a depth cue. This is true because it is practically impossible to place an image before your eyes that will cause convergence changes without the existence of disparity cues as well. It was proposed over one hundred years ago that the source for convergence depth cues is the set of eye muscles that controls eye movements. Nerve signals from these muscles have been recorded in the ocular nerve giving rise to the possibility that the brain monitors its own signals to these muscles. In spite of this, the results of most perception experiments point to a very minor role--if any--of convergence movements in depth perception.

However, the theory is appealing because of the psychic affinity that stereoscopic space seems to have with tactile space, as contrasted with the non-tactile nature of monoscopic space. Both stereoscopic images and tactile images share a psychic quality of disconnectiveness, and it may be that ocular muscle nerve signals play a role.

Eye convergence also results in the perceived phenomenon of crossed and uncrossed double images. In other words, if you are converged on an object two feet away, closer objects appear doubled and crossed (the right eye image of the closer object appears to the left of the left eye image) and farther objects appear doubled and uncrossed (the right eye image of the farther object appears to the right of the left eye image).

The role that these double images, by themselves, plays in depth perception is as difficult to determine as it is for blurred images. Both visual phenomena are almost subliminal because they are ignored in normal perceptual activity. In fact, we have difficulty in maintaining our awareness of the ever-present blurred and doubled images without sustained mental effort.

Disparity.

Binocular parallax is the basis for the image disparity that occurs on our two retinae, and disparity is the depth cue that results in stereopsis, an impression of space that is totally unique and unexpected. There is no way to describe to a one-eyed individual the quality of stereoscopic space, just as it is impossible to describe "red" to one who is color blind. As a psychic sensation of depth, stereopsis is singularly apart from the other depth cues.

The evolution of knowledge about stereoscopy was slow and difficult. The last major discovery by the English scientist, Sir Charles Wheatstone, was quite recent in comparison to other discoveries about the eye. While earlier scientists observed links between binocular parallax, image disparity, and stereoscopic perception, it was not until Wheatstone's major paper published in Philosophical Transactions in the year 1838 that the three features of binocular vision were linked in a complete causal relationship with the empirical proof provided by his own 3-D drawings.

Leonardo da Vinci studied and sketched human anatomy quite extensively in the 1500's A.D., but his drawings of the eye, while showing the optic nerve stretching into the brain, did not reveal the true anatomical arrangement of binocular vision. However, his artistic observations on the problem of representing space were far ahead of his time. Leonardo wrote that the art of painting can never reproduce space because painting lacks a quality he called "relievo," the relief of objects in space.

Another problem with early statements about perception was the lack of a known physical basis or an adequate theory for the "singleness" of subjective vision. The two optical nerves were found to terminate in separate hemispheres of the brain, and, thus, it was unclear how vision could have unity. There was speculation that internal fluids or "spirits" stimulated by the retinae were mingled somehow at the optical chiasma, but early drawings did not reveal the anatomical structure of this important juncture of the optical nerve tract.

One of the most important discoveries related to this problem was not made until the early l700s. Sir Isaac Newton, celebrated scientist, and John Taylor, English surgeon, noted a partial interchange of nerve fibers that occurs at the optic chiasma. From this discovery they concluded that single vision is a result of the union or fusion of homonymous "corresponding" images. They did not recognize, however, the other important effect of this union: stereopsis.

Stereoscopy

In retrospect, it is difficult to understand why the basic cause for stereopsis and the revelation that 3-D drawings could be created and viewed stereoscopically were not discovered until Wheatstone's magnificent breakthrough in 1833. Since 3-D drawings can be easily made and viewed without instruments or optical devices of any kind, there is no technical reason why these discoveries could not have occurred 2000 years ago rather than 147. Wheatstone's demonstration of his 3-D drawings required his mirror stereoscope, which was called by Sir John Herschel, "one of the most curious and beautiful for its simplicity in the entire range of experimental optics."

Since Wheatstone, the overwhelming conclusion of more than one hundred years of perception research is that retinal image disparities, alone, determine the quality and nature of the stereoscopic experience. Of course the cues of accommodation and convergence play an important role in assisting the eyes to "lock on" objects at various distances, but do not seem to affect seriously our psychic reconstruction of space. Whether or not under special conditions these two cues ever alter a stereo illusion is still an open question--one, perhaps, for the creative photographer.

Another aspect of this issue lies in a perceptual phenomenon that is unique to 3-D, the separation of accommodation and convergence planes. In natural viewing, these planes always coincide; that is, we automatically converge our eyes for the same distance that we focus. This is also true in viewing a hologram. However, a stereoscopic image cannot be viewed without a separation of these two functions--a fact that is quite important in 3-D projection systems, especially large theaters. For example, if you are sitting thirty feet from the screen, your eyes will remain focused for thirty feet regardless of where a 3-D object is projected--on the screen's surface, behind the screen at infinity, or in midair between the screen and your seat. There are several variables that must be considered in projecting 3-D images, because the greater the separation between accommodation and convergence distances, the greater the chance for eyestrain.

But, more interesting as an artistic issue is the fact that all depth planes of a 3-D image remain in focus regardless of on which plane you converge at any instant. One question arises: does this phenomenon divide forever the viewing experience of 3-D images from the experience of reality? Perhaps this is the major reason for the "hard-edged" quality or "cardboard" appearance of 3-D subjects, rather than the other photographic variables often cited.

Photographer Rudy Bender feels that because the 3-D image reproduces the original double-image gradient of objects, but not their original focus gradient--in fact, restricts all objects to a single focus plane--it should be regarded as a new kind of picture without precedent as a pictorial art form. In this regard, even a hologram is more akin to reality than it is to a stereograph. Thus, if the differences between stereo vision and natural vision can be clearly isolated and controlled as aesthetic qualities, they may become the key to exploring new visual realities. (For example, Bender has produced stereoscopic images that demonstrate his unique conception of a smoothly-changing stereo gradient from zero to maximum within the same scene.)

Stereoscopic vision has been called a primary factor in spatial orientation. It exists in babies at the earliest ages that can be measured, and thereby seems to be an innate quality of vision. Most other depth cues of vision are considered secondary in the sense that they are learned cues, derived from our previous experiences with objects.

Also, stereoscopic vision is considered a perception of relative depth rather than absolute distance. Your eyes do not work like a camera range finder for the purpose of determining a specific distance. It is nearly impossible to gauge your distance from one point of light in a totally dark room, although it is quite easy to tell which of two adjacent lights is closer. Our stereoscopic acuity for small differences in depth comparisons is quite high--as little as ten seconds of arc. And, since stereoscopic acuity is measured by parallax angle--a numerical constant regardless of object distance--the minimum distances between objects with a perceived change of relief vary dramatically.

This is a very important fact to remember. The farther away an object to be photographed is located, the greater it must be separated from other objects if the photographer's purpose is to isolate it stereoscopically. Stereoscopic vision impregnates local space more than distant space. Beyond our stereo infinity objects exist as if on the dome of a planetarium. Thus, the ancient Greek concept of the universe surrounding us like a celestial shell was a theory about physical reality with a clear correspondence to perceptual reality. Friedenwald has commented that this quality of stereoscopic vision--rich in volume nearby, shrunken with distance--is a "peculiar space" and one quite different from real space.

As discussed earlier, vision is considered a distance sense in contrast to touch, allowing for detached beholding, contemplation, and thought. But the reproduction of binocular vision may serve aesthetically as a bridge between sight and touch. Stereopsis results in a visual world, not of continuity, connection, and simple perspective, but of sudden immediacy, unexpectedness, and isolated objects--a kind of perception that shares much of its phenomenological feeling with our tactile and auditory senses.

Note that just as monoscopic illusions can be ambiguous, so can perceptual conflicts be created between monocular and binocular depth cues. Ittelson and other psychologists have studied the dynamics of cue conflicts in order to evaluate their relative importance, the underlying factors, the effect of learning, and the influence of cross-sensory conflicts, such as between vision and hearing. The classic subject for a stereo cue conflict is the human face. If the right-eye view of a face is displayed only to the left eye and the left-eye view to the right eye, the physical shape of the face should appear inverted with the result that it will look like the inside of a Halloween mask. But it doesn't. Monocular depth cues in the picture conflict with the stereo disparity cues, as well as our previous knowledge of a human face, and suppress the inversion. On the other hand, abstract subjects invert easily. There are little or no monocular cues to counter the stereo cues. A general rule should be remembered: the more familiar a subject is, the more its monocular depth cues will suppress any contradictory stereo depth cues in the final spatial perception.

Again, this potential in the hands of the photographer for creating and discovering inverted subjects and scenes is without precedent. In addition, he has the capability of altering not only the spatial volume of an object, a la the sculptor, but also the volume of the surrounding scene. Three major categories of stereoscopic manipulation are possible: space inversion, space scaling, and space synthesis.

Space inversion,

as explained earlier, is the inversion of near and far, the turning inside out of object points, or the creation of "negative" space (pseudostereo). It is stereoscopic space in reverse. Objects that are seen normally far away now protrude into the foreground with full binocular relief, and formerly close objects now recede into the background.

Space scaling

is the process of expanding or contracting the apparent volume of space. Since the human interocular distance is fixed at an average 68 mm, the apparent volume of familiar objects and their spatial relationships is fixed. Varying the interaxial distance of the stereo camera's lenses allows control over this important parameter all the way from zero to millions of miles. For example, increasing the camera's interaxial distance (hyper-stereoscopy) can change the appearance of a city to that of a small model. Decreasing the camera's interaxial distance can give a model an apparent parallax gradient scale indistinguishable from that of a real city. Stereoscopy gives the photographer the key to unlocking the binocular perception of volume.

Space synthesis

includes all processes in which two or more subjects are combined in a single stereoscopic image, by either split-image technique or, more often, complete super impositions. In fact, space synthesis is to stereo what montage is to cinema. The juxtaposition of two cinema shots in montage allows visual ideas to interact and produce new, possibly unrelated, visual ideas that are impossible to derive from the individual shots. The whole can become greater than the parts. In a similar manner, the superimposition of stereoscopic spaces, which may be inverted relative to each other or scaled differently, creates a new composite subject space quite different from the original scenes.

An agreed upon theory of stereoscopic vision has yet to be found. The value of theory for the creative stereographer lies in the new ideas for exploring visual depth that emerge from or lead to specific theories. Artists are familiar with the wealth of known visual illusions, such as used so ingeniously by the artist M. C. Escher, but almost no visual illusions centering on the stereoscopic experience have been discovered. (Random dot stereograms of hidden geometrical shapes are proposed in 1926 by Langlands and first produced with a digital computer by Bela Julesz in 1960. The use of Julesz stereograms in perception experiments, described as "incredible" by Harvard psychologists, showed that the human brain can merge highly-complex past and present visual images to trigger the perception of new binocular forms.) What is needed are pure stereo subjects that function like the classic Necker cube with contradictory or contrapuntal depth cues. They could be abstract forms, but, more interestingly, the stereographer might find or combine real objects whose novel depth ambiguities reveal something new about binocular reality. It seems highly possible that a careful, creative development of the stereo medium could prove or disprove existing theories or point the way to new perceptual experiences and new concepts of human vision.

Conclusion

The relationship between the perception of space and the portrayal of space has had a long and complex history. It has involved a continuing dialogue between artists and philosophers; interaction between theory and practice; and a symbiotic dependence on the tools of vision, both monoscopic and stereoscopic, that have evolved over the centuries.

Several types of visual media, such as painting, sculpture, photography, stereography, and holography, have been developed, each with different potentials and limits. I think that a fairly coherent evolution has taken place based primarily on the problems of portraying space, and, further, that only stereography and holography can solve the philosophical and aesthetic issues that have been raised by critics and artists.

Clearly, in terms of the expression of space, the binocular image is a logical next step in the evolution of art and photography. The stereo camera and the holographic laser will be essential tools that the artist/photographer must use if he or she is to nourish or lead future domains of science, ideas, and feelings. Of course, this is not to deny that beautiful, important work is produced in the prevailing monoscopic media, nor that the photographer's flat print will continue to be popular and valued in the future.

The creation of monocular images began with the European cave paintings of 20,000 years ago. In contrast, the first binocular images were Wheatstone's revolutionary 3-D drawings published in 1838. Since then, the practitioners of stereoscopy and holography have been scattered, few in number, and generally unrecognized. But, their enthusiasm and dedication have persisted. At present, the creative manipulation of binocular space, and not just the superb realism of stereoscopy, is of increasing interest. Photographers now realize that stereoscopic perception, like color perception, can be controlled artistically, and they have developed new techniques for doing so. A serious exploration of the essence of the binocular image is just beginning.

EVOLUTION OF BASIC STEREO CONCEPTS

B.C. 300 Euclid
A.D. 175 Claudius Galen

The eyes see objects differently.
1500 Leonardo da Vinci
Binocular vision adds a quality of relief to the perception of objects.
1611 Johann Kepler
1613 Francois Aguilonius

Binocular vision is single only at the plane of convergence; otherwise, images are doubled.
1738 Robert Smith
1759 W. Porterfield

Binocular parallax causes image disparities.
1775 Joseph Harris
Binocular parallax causes relief perception.
1833 Charles Wheatstone
Image disparities, the result of parallax, are the source of relief perception--or stereopsis.
1833 Charles Wheatstone
Images that produce stereopsis can be drawn.
1838 Charles Wheatstone
Space can be perceived inverted (pseudostereo).
1841 Charles Wheatstone
Binocular images can be made photographically.
1857 Hermann Helmholtz
The space in binocular images can be scaled (hyperstereo).

References:

Stereo Aesthetics

Arnheim, Rudolf, Film (London: Faber, 1933), pp. 154-160. Cf: Vesselo, "Stereoscopy--An 
   Answer to Arnheim," Sight & Sound, Winter 1934, pp.157-159. 
Benthall, "Holography and interference," Studio 179: 47, Feb. 1970.
Benyon, M., "Holographic image," Art and Artists 4: 45, Feb. 1970. 
Chandler, A.,''The Vision of Hyperspace,'' Stereo World (Nat'I. Stereo. Assoc., USA) 2:6, 
   Nov-Dec. 1975. Cf: Paul Wing, "Hyperspace--A Comment," Stereo World 3:1, J/F 1976.
Daniels, A.L., "Reflections of an Artist Surrounded by Scientists or, Through a Hologram Lightly,"
   Arts Canada 25: 69, Dec. 1968. 
Eisenstein, Sergei M., "About Stereoscopic Cinema," Penguin Film Review No. 8
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Holmes, Oliver Wendell, "The Stereoscope and the Stereograph," and "Sun-Painting and 
   Sun-Sculpture," Atlantic Monthly, 1859 and 1861. 
Layer, H.A., "Exploring Stereo Images: A Changing Awareness of Space in the Fine Arts," 
   Leonardo 4: 233, Summer 1971. 
Lindquist-Cock, E., "Stereoscopic Photography and the Western Paintings of Albert Bierstadt," 
   Art Quarterly, 33: 361, Winter 1970. 
Lowden, Jr., R.D., "Heywood--A Mysterious Stereo Artist," Stereo World 
   (Nat'I. Stereo. Assoc., USA) l:l, Jan.-Feb. 1975; Part 2, 1:2, March-April 1975. 
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   (Dover reprint: 1970), pp. 18-30. 
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References: Stereo Technique Brewster, D., The Stereoscope (London: John Murray, 1856). Brown, T., Stereoscopic Phenomena of Light & Sight (London: Gutenberg, 1903). Bush, V. & Rule, J.T., "Stereoscopic Photography," in Henney & Dudley's Handbook of Photography (NY: Whittlesey House, 1939). Cornwell-Clyne, A., 3-0 Kinematography & New Screen Techniques (London: Hutchinson, 1954). Dalzell, J.M., Practical Stereoscopic Photography (London: Technical Press, 1936, 1953). Dudley, L.P., Stereoptics (London: MacDonald & Co., 1951). Gowland, P., The Art & Technique of Stereo Photography (NY: Crown, 1954). Judge, A.W., Stereoscopic Photography (London: Chapman & Hall, 1926, 1935, 1950). Kaiser, J.B., Make Your Own Stereo Pictures (NY: Macmillan, 1955). Krause, E.E., Three-Dimensional Projection (NY: Greenberg, 1954). Kriebel, R.T., "Stereoscopic Photography," in The Complete Photographer, Nos. 51 and 53, pp. 3308-3318 and 3463-3466 (Cambridge: Polaroid Corp., 1943). Linssen, E.F., Stereo-Photography in Practice (London: Fountain Press, 1 952). Mahler, J., "Modern Stereo Techniques," Photo. Sci. & Tech., 11 (3): 1954, pp. 84-89. McKay, H.C., Three-Dimensional Photography (NY: American Photography, 1951, 1953). Morgan, W.D. let al), Stereo Realist Manual (NY: Morgan & Lester, 1954). Norling, J.A., "The Stereoscopic Art--A Reprint," SMPTE J. 60(3). 1953, pp. 268-308. Okoshi, T., Three-Dimensional Imagery Techniques (NY: Academic Press, 1976). Spottiswoode, R., Theory of Stereoscopic Transmission (Berkeley: U. of Cal., 1953). Symons, K.C.M., Stereo Photography (London: Focal Press, 1957). Thomson, C.L., Build Your Own Stereo Equipment (London: Fountain Press, 1954). Valyus, N.A., Stereoscopy (London: Focal Press, 1966). Wilman, C.W., Simplified Stereoscopic Photography (London: Percival Marshall, 1949).

References: Art and Perception Bann, S., Experimental Painting: Construction, Abstraction, Destruction, Reduction (NY: Universe Books, 1970). Freidenwald, J.S., "Knowledge of Space Perception and the Portrayal of Depth in Painting, College Art Journal, 15(2), 1955, pp. 96-112. Gibson, J.J., The Perception of the Visual World (Cambridge: Riverside, 1950). Guggenheimer, R.H., Sight and insight (NY: Harper & Bros., 1945). Ittelson, W.H., Visual Space Perception (NY: Springer, 1960). Ivins, W., On the Rationalization of Sight (NY: Metropolitan Museum, 1938). Ivins, W., Art and Geometry: A Study in Space intuitions (Cambridge: Harvard, 1946). Johnson, M., Art and Scientific Thought (NY: Columbia U. Press, 1949). Julesz, Bela, Foundations of Cyclopean Perception (Chicago: U. of Chicago Press, 1971). Moholy-Nagy, L., Vision in Motion (Chicago: Paul Theobald, 1947). Mondrian, P., Plastic Art and the Pure Plastic Art (NY: Wittenborn, 1945). Mueller, R.E., The Science of Art (NY: John Day Co., 1967). Ogle, K.N., Binocular Vision (Philadelphia: Saunders, 1950). Panovsky, The Coder Huygens and Leonardo da Vinci's Art Theory (London: Warburg Institute, 1940). Parker, H.W., "Notes on Perception," Harvard Art Review, Winter 1967. Pinchbeck, P., "Structure of Reality in image and Word," Arts Magazine, April 1972. Polyak, S.L., The Vertebrate Visual System (Chicago: U. of 1ll. 18 Press,1957). Richardson, J.A., Modern Art and Scientific Thought (U rbana: U. of 111. Press, 1971). Senden, M., Space and Sight (London: Methuen & Co., 1960). Spies, Werner, Vasarely (NY: Abrams, 1969). Wheatstone, C., "On Some Remarkable, and Hitherto Unobserved Phenomena of Binocular Vision," Part I: London R. Sec. Philos. Trans., 1838, pp. 371-394; Part II: Philos. Mag. Series, 1852, pp. 504-523. White, J., The Birth and Rebirth of Pictorial Space (London: Faber & Faber, 1957).



The following captions are for stereoscopic images in the original 1979 article, several of which the editor neglected to include: An untitled, anonymous stereograph, c.1895., page 34 One of the earliest examples ever found by the author of stereoscopic split-image space synthesis. (reproduced top of article) A Study in Alternity: Metropolis Sequence #14 by Rudy Bender, USA, 1979, page 37 A Study in Alternity: Floating Dream Sequence by Rudy Bender, USA, 1979, page 37 Untitled by Lorran Meares, USA, 1977, page 38 Sarah Walking by Rudy Bender, USA, 1966, page 39 Untitled-1, from Projection [a stereo book] Tom Petrillo, USA, 1978, page 43 Untitled-2, from Mound Ten Views [a stereo book] Tom Petrillo, USA, 1977, page 43 Untitled-3, from Projection [a stereo book] Tom Petrillo, USA, 1978, page 43 Untitled-1, Charles Swedlund, USA, 1973, page 44 Untitled-2, Charles Swedlund, USA, 1973, page 48

Related stereoscopy links

California Museum of Photography's Keystone-Mast Collection
MIT Museum: Holography Collection
3-D by Dan Shelley.
Rocky Mountain Memories
National Stereoscopic Association
Reel 3-D Enterprises, Inc.
International Stereoscopic Union
Stereoscopic Displays & Applications
SPIE Photonics West
stereoscopy.com links page




This article was translated into Spanish and published in a
beautifully illustrated book on the history of stereoscopy
"La Imagen Estereoscopica" by Juan Antonio Fernandez Rivero
(Malaga, Editorial Miramar, 2004, 240 pages)

Click here for further information.



This web page is dedicated to RUDY BENDER
A great friend, a 3-D theoretician and 3-D photographer of incredible talent.
Rudy died too young--a sad loss for the world of 3-D and a sad loss for the
Internet--he would have loved its potential for 3-D art.

sample stereoscopic image by Rudy

Some of his documents and work are on deposit at the:
Center for Creative Photography
The University of Arizona, P.O. Box 210103, Tucson, AZ 85721
Ph: 520-621-7968 Fax: 520-621-9444 Email: oncenter@ccp.arizona.edu

If you have anything regarding Rudy to contribute,
or are interested in his work, please contact the Center.

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