1.1 INTRODUCTION
The term telepresence was first used in the context of teleoperation by Marvin Minsky (suggested to him by his friend Pat Gunkel) in a bold 1979 funding proposal Toward a Remotely-Manned Energy and Production Economy, the essentials of which were laid down in his classic 1980 paper on the topic (Minsky 1980). It refers to the phenomenon that a human operator develops a sense of being physically present at a remote location through interaction with the system’s human interface, that is, through the user’s actions and the subsequent perceptual feedback he/she receives via the appropriate teleoperation technology.
The concept of presence had been discussed earlier in the context of theatrical perfor-mances, where actors are said to have a ‘stage presence’ (to indicate a certain strength and convincingness in the actor’s stage appearance and performance). Bazin (1967) also discussed this type of presence in relation to photography and cinema. He writes:
Presence, naturally, is defined in terms of time and space. ‘To be in the presence of someone’
is to recognise him as existing contemporaneously with us and to note that he comes within the actual range of our senses – in the case of cinema of our sight and in radio of our hearing. Before the arrival of photography and later of cinema, the plastic arts (especially portraiture) were the only intermediaries between actual physical presence and absence. Bazin (1967), p. 96, originally published inEspritin 1951.
Bazin noted that in theatre, actors and spectators have a reciprocal relationship, both being able to respond to each other within shared time and space. With television, and any other broadcast medium, this reciprocity is incomplete in one direction, adding a new variant of
‘pseudopresence’ between presence and absence. Bazin:
The spectator sees without being seen. There is no return Flow Nevertheless, this state of not being present is not truly an absence. The television actor has a sense of the million of ears and eyes virtually present and represented by the electronic camera. Bazin (1967), p. 97, footnote.
3D Videocommunication — Algorithms, concepts and real-time systems in human centred communication Edited by O. Schreer, P. Kauff and T. Sikora © 2005 John Wiley & Sons, Ltd
The sense of being togetherand interacting with others within a real physical space can be traced back to the work of Goffman (1963), who used the concept of co-presence to indicate the individual’s sense of perceiving others as well as the awareness of others being able to perceive the individual:
The full conditions of co-presence, however, are found in less variable circumstances: persons must sense that they are close enough to be perceived in whatever they are doing, including their experiencing of others, and close enough to be perceived in this sensing of being perceived.
Goffman (1963), p. 17.
This mutual and recursive awareness has a range of consequences on how individuals present themselves to others. Note, however, that Goffman applied the concept of co-presence only to social interactions in ‘real’ physical space. In our current society, the sense of co-presencethrough a mediumis of significant importance as a growing number of our human social interactions are mediated, rather than co-located in physical space.
Since the early 1990s onwards, presence has been studied in relation to various media, most notably virtual environments (VEs). Sheridan (1992) refers to presence elicited by a VE as ‘virtual presence’, whereas he uses ‘telepresence’ for the case of teleoperation that Minsky (1980) was referring to. From the point of view of psychological analysis, a distinction based on enabling technologies is unnecessary and the broader termpresenceis used in this chapter to include both variations.
A number of authors have used the terms ‘presence’ and ‘immersion’ interchangeably, as they regard them as essentially the same thing. However, in this chapter, they are considered as different concepts, in line with, for instance, Slater and Wilbur (1997) and Draper et al.
(1998). Immersion is a term which is reserved here for describing a set of physical properties of the media technology that may give rise to presence. A media system that offers display and tracking technologies that match and support the spatial and temporal fidelity of real-world perception and action is considered immersive. For an overview of criteria in the visual domain, see IJsselsteijn (2003). In a similar vein, Slater and Wilbur (1997) refer to immersion as the objectively measurable properties of a VE. According to them it is the ‘extent to which computer displays are capable of delivering an inclusive, extensive, surrounding, and vivid illusion of reality to the senses of the VE participant’ (p. 604).
Presence can be conceptualised as the experiential counterpartof immersion — the human response. Presence and immersion are logically separable, yet several studies show a strong empirical relationship, as highly immersive systems are likely to engender a high degree of presence for the participant.
Lombard and Ditton (1997) reviewed a broad body of literature related to presence and iden-tified six different conceptualizations of presence: realism, immersion, transportation, social richness, social actor within medium, and medium as social actor. Based on the commonalities between these different conceptualizations, they provide a unifying definition of presence as theperceptual illusion of non-mediation, that is, the extent to which a person fails to perceive or acknowledge the existence of a medium during a technologically mediated experience. The conceptualizations Lombard and Ditton identified can roughly be divided into two broad cate-gories –physicalandsocial. The physical category refers to the sense of being physically located in mediated space, whereas the social category refers to the feeling of being together, of social interaction with a virtual or remotely located communication partner. At the intersection of these two categories, we can identifyco-presenceor a sense of being together in a shared space at the same time, combining significant characteristics of both physical and social presence.
1.1 INTRODUCTION 9
Figure 1.1 A graphical illustration of the relationship between physical presence, social presence and co-presence, with various media examples. Abbreviations: VR=virtual reality; LBE=location-based entertainment; SVEs=shared virtual environments; MUDs=multi-user dungeons. Technologies vary in both spatial and temporal fidelity
Figure 1.1 illustrates this relationship with a number of media examples that support the different types of presence to a varying extent. The examples vary significantly in both spatial and temporal fidelity. For example, while a painting may not necessarily represent physical space with a great degree of accuracy (although there are examples to the contrary, as we shall see), interactive computer graphics (i.e., virtual environments) have the potential to engender a convincing sense of physical space by immersing the participant and sup-porting head-related movement parallax. For communication systems, the extent to which synchronous communication is supported varies considerably. Time-lags are significant in the case of letters, and almost absent in the case of telephone or videoconferencing.
It is clear that physical and social presence are distinct categories that can and should be meaningfully distinguished. Whereas a unifying definition, such as the one provided by Lombard and Ditton (1997), accentuates the common elements of these different categories, it is of considerable practical importance to keep the differences between these categories in mind as well. The obvious difference is that ofcommunicationwhich is central to social presence, but unnecessary to establish a sense of physical presence. Indeed, a medium can provide a high degree of physical presence without having the capacity for transmitting recip-rocal communicative signals at all. Conversely, one can experience a certain amount of social presence, or the ‘nearness’ of communication partners, using applications that supply only a minimal physical representation, as is the case, for example, with telephone or internet chat.
This is not to say, however, that the two types of presence are unrelated. There are likely to be a number of common determinants, such as the immediacy of the interaction, that are relevant to both social and physical presence. As illustrated in Figure 1.1, applications such as videoconferencing or shared virtual environments are in fact based on providing a mix of both the physical and social components. The extent to which shared space adds to the social component is an empirical question, but several studies have shown that as technology increasingly conveys non-verbal communicative cues, such as facial expression, gaze direction, gestures, or posture, social presence will increase.
In the remainder of this introductory chapter the historical development of a number of relevant presence technologies is described, with particular emphasis on their psychological impact. Though most media discussed here are relatively recent, the desire to render the
real and the magical, to create illusory deceptions, and to transcend our physical and mortal existence may be traced back tens of thousands of years, to paleolithic people painting in a precisely distorted, or anamorphic, manner on the natural protuberances and depressions of cave walls in order to generate a three-dimensional appearance of hunting scenes. These paintings subtly remind us that, in spite of the impressive technological advances of today, our interests in constructing experiences through media are by no means recent. It is beyond the scope of this chapter to provide an exhaustive historical analysis; rather we want to inform our current endeavors and place them in a somewhat more humbling perspective.
1.2 THE ART OF IMMERSION: BARKER’S PANORAMAS
On June 17, 1787 Irish painter Robert Barker received a patent for a process under the name of ‘la nature à coup d’oeil’ by means of which he could depict a wide vista onto a completely circular surface in correct perspective. The Repertory of Artswhich published the patent specifications in 1796 noted: ‘This invention has since been called Panorama’
(Oettermann 1997). Today, the term Panorama is used to denote a view or vista from an elevated lookout point, or, more metaphorically, to refer to an overview or survey of a particular body of knowledge, such art or literature. In the late 18th century, however, it was in fact a neologism created from two Greek roots, pan, meaning ‘all’, and horama, meaning ‘view’, to specifically describe the form of landscape painting which reproduced a 360-degree view. Its common usage today reflects some of the success of this art form at the time of its introduction.
The aim of the panorama was to convincingly reproduce the real world such that spectators would be tricked into believing that what they were seeing was genuine. Illusionistic or trompe l’oeil paintings had been a well-known phenomenon since Roman times, and such paintings would create the illusion of, for instance, walls containing a window to the outside world or a ceiling containing a view to the open sky. However, an observer’s gaze can always move beyond the frame, where the physical surroundings often contradict the content of the painted world.
With panoramas, any glimpse of the real physical environment is obscured as the painting completely surrounds the viewer. Often, an observation platform with an umbrella-shaped roof (velum) was constructed such that the upper edge of the unframed canvas would be obscured from view (see Figure 1.2). The bottom edge of the painting would be obscured through either the observation platform itself or by means of some faux terrain stretching out between the platform and the canvas.
For example, the well-known Panorama Mesdag, painted in 1881 by Hendrik Willem Mesdag, offers a mesmerising view of the Dutch coast at Scheveningen. In the foreground, a real sandy beach with seaweed, fishing nets, anchors, and other assorted sea-related paraphernalia is visible and connects seamlessly to the beach in the painting. The top of the canvas is obscured through the roof of the beach tent one enters as one ascends the staircase, and emerges onto the viewing platform, surrounded by a balustrade. The viewer is completely surrounded by the illusionistic painting, which becomes particularly convincing as one looks out into the distance, where neither stereoscopic vision nor head-related movement parallax can provide conflicting information about the perceptual reality of what one is seeing.
Barker’s first panoramic painting was a 21-metre-long 180-degree view of Edinburgh, the city where Barker worked as a drawing teacher. His ‘breakthrough’ piece, however, was the Panorama of London, first exhibited in 1792. After a successful tour of the English provinces,
1.3 CINERAMA AND SENSORAMA 11
Figure 1.2 Cross-section of a panorama, consisting of: (A) entrance and box office, (B) darkened corridor and stairs, (C) observation platform, (D) umbrella-shaped roof, (E) observer’s vertical angle of view, and (F) false terrain in the foreground
the panorama was shipped to the continent in 1799, to be first exhibited in Hamburg, Germany. A local paper, thePrivilegirte Wöchentliche Gemeinnützige Nachrichten von und für Hamburgwrote in a review:
It is most admirable. The visitor finds himself at the same spot on which the artist stood to make his sketch, namely on the roof of a mill, and from here has a most felicitous view of this great city and its environs in superb perspective. I would estimate that the viewer stands at a distance of some six paces from the exquisitely fashioned painting, so close that I wanted to reach out and touch it - but could not. I then wished there had been a little rope ladder tied to the railing on the roof of the mill, so I could have climbed down and joined the crowds crossing Blackfriar’s Bridge on their way into the city. Quoted in Oettermann (1997), p. 185.
Seeing the same painting exhibited in Paris another reviewer commented for the German Journal London und Paris:
No one leaves such a panorama dissatisfied, for who does not enjoy an imaginary journey of the mind, leaving one’s present surroundings to rove in other regions! And the person who can travel in this manner to a panorama of his native country must enjoy the sweetest delight of all. Quoted in Oettermann (1997), p. 148.
Over the 19th century the panorama developed into a true mass medium, with millions of people visiting various panoramic paintings all across Europe, immersing themselves in the scenery of various great battles, admiring famous cities, or significant historic events.
The panorama had many offshoots, most notably perhaps Daguerre’s Diorama introduced in the 1820s, as well as the late 19th century Photorama by the Lumière brothers, and Grimoin-Sanson’s Cinéorama, both of which applied film instead of painting. Fifty years later, when Hollywood needed to counter dropping box office receipts due to the introduction of television, attention turned again to a cinematographic panorama.
1.3 CINERAMA AND SENSORAMA
Cinerama, developed by inventor Fred Waller, used three 35 mm projections on a curved screen to create a 146-degree panorama. In addition to the impressive visuals, Cinerama also included a seven-channel directional sound system which added considerably to its psychological impact. Cinerama debuted at the Broadway Theatre, New York in 1952,
with the independent production This Is Cinerama, containing the famous scene of the vertigo-inducing roller coaster ride, and was an instant success. The ads forThis is Cinerama promised: ‘You won’t be gazing at a movie screen — you’ll find yourself swept right into the picture, surrounded with sight and sound.’ The film’s program booklet proclaimed:
You gasp and thrill with the excitement of a vividly realistic ride on the roller coaster You feel the giddy sensations of a plane flight as you bank and turn over Niagara and skim through the rocky grandeur of the Grand Canyon. Everything that happens on the curved Cinerama screen is hap-pening to you. And without moving from your seat, you share, personally, in the most remarkable new kind of emotional experience ever brought to the theater. Belton (1992), p. 189.
Interestingly, a precursor of the Cinerama system from the late 1930s — a projection sys-tem known asVitarama— developed into what can be regarded as a forerunner of modern interactive simulation systems and arcade games. Vitarama consisted of a hemispherical pro-jection of eleven interlocked 16 mm film tracks, filling the field of vision, and was adapted during the Second World War to a gunnery simulation system. TheWaller Flexible Gunnery Trainer, named after its inventor, projected a film of attacking aircraft and included an electro-mechanical system for firing simulation and real-time positive feedback to the gunner if a target was hit. The gunnery trainer’s displays were in fact already almost identical to the Cin-erama system, so Waller did not have to do much work to convert it into the CinCin-erama system.
The perceptual effect of the widescreen presentation of motion pictures is that, while we focus more locally on character and content, the layout and motion presented to our peripheral visual systems surrounding that focus very much control our visceral responses.
Moreover, peripheral vision is known to be more motion-sensitive than foveal vision, thereby heightening the impact of movement and optic flow patterns in the periphery, such as those engendered by a roller coaster sequence.
As Belton (1992) notes, the widescreen experience marked a new kind of relation between the spectator and the screen. Traditional narrow-screen motion pictures became associated, at least from an industry marketing point of view, with passive viewing. Widescreen cin-ema, on the other hand, became identified with the notion of audience participation— a heightened sense of engagement and physiological arousal as a consequence of the immer-sive wraparound widescreen image and multitrack stereo sound. The type of visceral thrills offered by Cinerama was not unlike the recreational participation that could be experienced at an amusement park, and Cinerama ads (Figure 1.3) often accentuated the audience’s par-ticipatory activity by depicting them as part of the on-screen picture, such as sitting in the front seat of a roller coaster, ‘skiing’ side by side with on-screen water skiiers, or hovering above the wings of airplanes (Belton 1992).
Unfortunately however, Cinerama’s three projector system was costly for cinemas to install, seating capacity was lost to accommodate the level projection, required and a staff of seventeen people was needed to operate the system. In addition, Cinerama films were expensive to produce, and sometimes suffered from technical flaws. In particular, the seams where the three images were joined together were distractingly visible, an effect accentuated by variations in projector illumination (Belton 1992). Together these drawbacks prevented Cinerama from capitalizing on its initial success.
Following Cinerama, numerous other film formats have attempted to enhance the viewer’s cinematic experience by using immersive projection and directional sound, with varying success. Today, the change to a wider aspect ratio, 1.65:1 or 1.85:1, has become a cinematic standard. In addition, some very large screen systems have been developed, of which IMAX, introduced at the World Fair in Osaka, Japan in 1970, is perhaps the best-known. When
1.3 CINERAMA AND SENSORAMA 13
Figure 1.3 Advertisement for Cinerama, 1952
projected, the horizontally run 70 mm IMAX film, the largest frame ever used in motion pictures, is displayed on screens as large as 30 ×22.5 m, with outstanding sharpness and brightness. By seating the public on steeply raked seats relatively close to the slightly curved screen, the image becomes highly immersive. As the ISC publicity says, ‘IMAX films bring distant, exciting worlds within your grasp It’s the next best thing to being there’ (Wollen 1993). IMAX has also introduced a stereoscopic version, 3-D Imax, and a hemispherical one known as Omnimax. IMAX and other large-format theaters have been
projected, the horizontally run 70 mm IMAX film, the largest frame ever used in motion pictures, is displayed on screens as large as 30 ×22.5 m, with outstanding sharpness and brightness. By seating the public on steeply raked seats relatively close to the slightly curved screen, the image becomes highly immersive. As the ISC publicity says, ‘IMAX films bring distant, exciting worlds within your grasp It’s the next best thing to being there’ (Wollen 1993). IMAX has also introduced a stereoscopic version, 3-D Imax, and a hemispherical one known as Omnimax. IMAX and other large-format theaters have been