Virtual Rear Projection: A Comparison Study of Projection Technologies for Large Interactive Displays

Rear projection of large-scale upright displays is often preferred over front projection because of the elimination of shadows that occlude the projected image. However, rear projection is not always a feasible option for space and cost reasons. Recent research suggests that many of the desirable features of rear projection, in particular shadow elimination, can be reproduced using new front projection techniques. We report on an empirical study to determine how two of these new projection techniques compare with traditional rear projection and front projection, with the hope of motivating the continued advance of improved virtual rear projection techniques

Interactive Walls: Addressing the Challenges of Large-scale Interactive Surfaces

We present a prototype large-scale interactive electronic whiteboard wall. Various input, output and vision technologies are used to create a surface that can capture digital ink as well as support pen-based interaction with displayed information on subregions of the wall. A simple automated capture application is demonstrated on our prototype surface and research challenges for developing more complex applications with this interactive technology are discussed

Gaze, Posture and Gesture Recognition to Minimize Focus Shifts for Intelligent Operating Rooms in a Collaborative Support System

This paper describes the design of intelligent, collaborative operating rooms based on highly intuitive, natural and multimodal interaction. Intelligent operating rooms minimize surgeon’s focus shifts by minimizing both the focus spatial offset (distance moved by surgeon’s head or gaze to the new target) and the movement spatial offset (distance surgeon covers physically). These spatio-temporal measures have an impact on the surgeon’s performance in the operating room. I describe how machine vision techniques are used to extract spatio-temporal measures and to interact with the system, and how computer graphics techniques can be used to display visual medical information effectively and rapidly. Design considerations are discussed and examples showing the feasibility of the different approaches are presented

Media Space: an analysis of spatial practices in planar pictorial media.

The thesis analyses the visual space displayed in pictures, film, television and digital interactive media. The argument is developed that depictions are informed by the objectives of the artefact as much as by any simple visual correspondence to the observed world. The simple concept of ‘realism’ is therefore anatomised and a more pragmatic theory proposed which resolves some of the traditional controversies concerning the relation between depiction and vision. This is then applied to the special problems of digital interactive media. An introductory chapter outlines the topic area and the main argument and provides an initial definition of terms. To provide a foundation for the ensuing arguments, a brief account is given of two existing and contrasted approaches to the notion of space: that of perception science which gives priority to acultural aspects, and that of visual culture which emphasises aspects which are culturally contingent. An existing approach to spatial perception (that of JJ Gibson originating in the 1940s and 50s) is applied to spatial depiction in order to explore the differences between seeing and picturing, and also to emphasise the many different cues for spatial perception beyond those commonly considered (such as binocularity and linear perspective). At this stage a simple framework of depiction is introduced which identifies five components or phases: the objectives of the picture, the idea chosen to embody the objectives, the model (essentially, the visual ‘subject matter’), the characteristics of the view and finally the substantive picture or depiction itself. This framework draws attention to the way in which each of the five phases presents an opportunity for decision-making about representation. The framework is used and refined throughout the thesis. Since pictures are considered in some everyday sense to be ‘realistic’ (otherwise, in terms of this thesis, they would not count as depictions), the nature of realism is considered at some length. The apparently unitary concept is broken down into several different types of realism and it is argued that, like the different spatial cues, each lends itself to particular objectives intended for the artefact. From these several types, two approaches to realism are identified, one prioritising the creation of a true illusion (that the picture is in fact a scene) and the other (of which there are innumerably more examples both across cultures and over historical time) one which evokes aspects of vision without aiming to exactly imitate the optical stimulus of the scene. Various reasons for the latter approach, and the variety of spatial practices to which it leads, are discussed. In addition to analysing traditional pictures, computer graphics images are discussed in conjunction with the claims for realism offered by their authors. In the process, informational and affective aspects of picture-making are distinguished, a distinction which it is argued is useful and too seldom made. Discussion of still pictures identifies the evocation of movement (and other aspects of time) as one of the principal motives for departing from attempts at straightforward optical matching. The discussion proceeds to the subject of film where, perhaps surprisingly now that the depiction of movement is possible, the lack of straightforward imitation of the optical is noteworthy again. This is especially true of the relationship between shots rather than within them; the reasons for this are analysed. This reinforces the argument that the spatial form of the fiction film, like that of other kinds of depiction, arises from its objectives, presenting realism once again as a contingent concept. The separation of depiction into two broad classes – one which aims to negate its own mediation, to seem transparent to what it depicts, and one which presents the fact of depiction ostensively to the viewer – is carried through from still pictures, via film, into a discussion of factual television and finally of digital interactive media. The example of factual television is chosen to emphasise how, despite the similarities between the technologies of film and television, spatial practices within some television genres contrast strongly with those of the mainstream fiction film. By considering historic examples, it is shown that many of the spatial practices now familiar in factual television were gradually expunged from the classical film when the latter became centred on the concerns of narrative fiction. By situating the spaces of interactive media in the context of other kinds of pictorial space, questions are addressed concerning the transferability of spatial usages from traditional media to those which are interactive. During the thesis the spatial practices of still-picture-making, film and television are characterised as ‘mature’ and ‘expressive’ (terms which are defined in the text). By contrast the spatial practices of digital interactive media are seen to be immature and inexpressive. It is argued that this is to some degree inevitable given the context in which interactive media artefacts are made and experienced – the lack of a shared ‘language’ or languages in any new media. Some of the difficult spatial problems which digital interactive media need to overcome are identified, especially where, as is currently normal, interaction is based on the relation between a pointer and visible objects within a depiction. The range of existing practice in digital interactive media is classified in a seven-part taxonomy, which again makes use of the objective-idea-model-view-picture framework, and again draws out the difference between self-concealing approaches to depiction and those which offer awareness of depiction as a significant component of the experience. The analysis indicates promising lines of enquiry for the future and emphasises the need for further innovation. Finally the main arguments are summarised and the thesis concludes with a short discussion of the implications for design arising from the key concepts identified – expressivity and maturity, pragmatism and realism

Media Space: an analysis of spatial practices in planar pictorial media.

The thesis analyses the visual space displayed in pictures, film, television and digital interactive media. The argument is developed that depictions are informed by the objectives of the artefact as much as by any simple visual correspondence to the observed world. The simple concept of ‘realism’ is therefore anatomised and a more pragmatic theory proposed which resolves some of the traditional controversies concerning the relation between depiction and vision. This is then applied to the special problems of digital interactive media. An introductory chapter outlines the topic area and the main argument and provides an initial definition of terms. To provide a foundation for the ensuing arguments, a brief account is given of two existing and contrasted approaches to the notion of space: that of perception science which gives priority to acultural aspects, and that of visual culture which emphasises aspects which are culturally contingent. An existing approach to spatial perception (that of JJ Gibson originating in the 1940s and 50s) is applied to spatial depiction in order to explore the differences between seeing and picturing, and also to emphasise the many different cues for spatial perception beyond those commonly considered (such as binocularity and linear perspective). At this stage a simple framework of depiction is introduced which identifies five components or phases: the objectives of the picture, the idea chosen to embody the objectives, the model (essentially, the visual ‘subject matter’), the characteristics of the view and finally the substantive picture or depiction itself. This framework draws attention to the way in which each of the five phases presents an opportunity for decision-making about representation. The framework is used and refined throughout the thesis. Since pictures are considered in some everyday sense to be ‘realistic’ (otherwise, in terms of this thesis, they would not count as depictions), the nature of realism is considered at some length. The apparently unitary concept is broken down into several different types of realism and it is argued that, like the different spatial cues, each lends itself to particular objectives intended for the artefact. From these several types, two approaches to realism are identified, one prioritising the creation of a true illusion (that the picture is in fact a scene) and the other (of which there are innumerably more examples both across cultures and over historical time) one which evokes aspects of vision without aiming to exactly imitate the optical stimulus of the scene. Various reasons for the latter approach, and the variety of spatial practices to which it leads, are discussed. In addition to analysing traditional pictures, computer graphics images are discussed in conjunction with the claims for realism offered by their authors. In the process, informational and affective aspects of picture-making are distinguished, a distinction which it is argued is useful and too seldom made. Discussion of still pictures identifies the evocation of movement (and other aspects of time) as one of the principal motives for departing from attempts at straightforward optical matching. The discussion proceeds to the subject of film where, perhaps surprisingly now that the depiction of movement is possible, the lack of straightforward imitation of the optical is noteworthy again. This is especially true of the relationship between shots rather than within them; the reasons for this are analysed. This reinforces the argument that the spatial form of the fiction film, like that of other kinds of depiction, arises from its objectives, presenting realism once again as a contingent concept. The separation of depiction into two broad classes – one which aims to negate its own mediation, to seem transparent to what it depicts, and one which presents the fact of depiction ostensively to the viewer – is carried through from still pictures, via film, into a discussion of factual television and finally of digital interactive media. The example of factual television is chosen to emphasise how, despite the similarities between the technologies of film and television, spatial practices within some television genres contrast strongly with those of the mainstream fiction film. By considering historic examples, it is shown that many of the spatial practices now familiar in factual television were gradually expunged from the classical film when the latter became centred on the concerns of narrative fiction. By situating the spaces of interactive media in the context of other kinds of pictorial space, questions are addressed concerning the transferability of spatial usages from traditional media to those which are interactive. During the thesis the spatial practices of still-picture-making, film and television are characterised as ‘mature’ and ‘expressive’ (terms which are defined in the text). By contrast the spatial practices of digital interactive media are seen to be immature and inexpressive. It is argued that this is to some degree inevitable given the context in which interactive media artefacts are made and experienced – the lack of a shared ‘language’ or languages in any new media. Some of the difficult spatial problems which digital interactive media need to overcome are identified, especially where, as is currently normal, interaction is based on the relation between a pointer and visible objects within a depiction. The range of existing practice in digital interactive media is classified in a seven-part taxonomy, which again makes use of the objective-idea-model-view-picture framework, and again draws out the difference between self-concealing approaches to depiction and those which offer awareness of depiction as a significant component of the experience. The analysis indicates promising lines of enquiry for the future and emphasises the need for further innovation. Finally the main arguments are summarised and the thesis concludes with a short discussion of the implications for design arising from the key concepts identified – expressivity and maturity, pragmatism and realism

Toolkit support for interactive projected displays

Interactive projected displays are an emerging class of computer interface with the potential to transform interactions with surfaces in physical environments. They distinguish themselves from other visual output technologies, for instance LCD screens, by overlaying content onto the physical world. They can appear, disappear, and reconfigure themselves to suit a range of application scenarios, physical settings, and user needs. These properties have attracted significant academic research interest, yet the surrounding technical challenges and lack of application developer tools limit adoption to those with advanced technical skills. These barriers prevent people with different expertise from engaging, iteratively evaluating deployments, and thus building a strong community understanding of the technology in context. We argue that creating and deploying interactive projected displays should take hours, not weeks. This thesis addresses these difficulties through the construction of a toolkit that effectively facilitates user innovation with interactive projected displays. The toolkit’s design is informed by a review of related work and a series of in-depth research probes that study different application scenarios. These findings result in toolkit requirements that are then integrated into a cohesive design and implementation. This implementation is evaluated to determine its strengths, limitations, and effectiveness at facilitating the development of applied interactive projected displays. The toolkit is released to support users in the real-world and its adoption studied. The findings describe a range of real application scenarios, case studies, and increase academic understanding of applied interactive projected display toolkits. By significantly lowering the complexity, time, and skills required to develop and deploy interactive projected displays, a diverse community of over 2,000 individual users have applied the toolkit to their own projects. Widespread adoption beyond the computer-science academic community will continue to stimulate an exciting new wave of interactive projected display applications that transfer computing functionality into physical spaces

Screen Genealogies

Against the grain of the growing literature on screens, *Screen Genealogies* argues that the present excess of screens cannot be understood as an expansion and multiplication of the movie screen nor of the video display. Rather, screens continually exceed the optical histories in which they are most commonly inscribed. As contemporary screens become increasingly decomposed into a distributed field of technologically interconnected surfaces and interfaces, we more readily recognize the deeper spatial and environmental interventions that have long been a property of screens. For most of its history, a screen was a filter, a divide, a shelter, or a camouflage. A genealogy stressing transformation and descent rather than origins and roots emphasizes a deeper set of intersecting and competing definitions of the screen, enabling new thinking about what the screen might yet become

Torture, text and the reformulation of spiritual identity in old English religious verse

The Introduction to this thesis includes a brief discussion of various understandings of what torture is, and a statement of the definition of torture adopted for the purposes of this study. Torture, as it is examined in this study, is not so much an act of violence as it is a violent process; that is, torture is a means, not an end in itself, and torture always presupposes intent and causality. Chapter One provides the historical and legal contexts for later literary and theoretical discussions of torture. This chapter is divided into two parts, the first dealing with instances of torture which appear in Anglo-Saxon historical records, and the second dealing with legal codes which are concerned with torture. In the course of this chapter it becomes apparent that torture as a public act serves as a document of sorts, sometimes recording and sometimes interpreting political realities. Any study of torture must be grounded in an understanding of pain, and Chapter Two is concerned with the nature of pain, and with its relationship to torture. The paradox of pain is that it is universal and at the same time isolating and inexpressible. In Chapter Two, a close examination of the language and structure of The Dream of the Rood serves to illustrate that the Anglo-Saxons understood this paradox. The graphic and sometimes almost loving detail with which the poet describes the passion of Christ functions as a language "of weapons and wounds", and helps to convey, in some measure, the almost incommunicable nature of intense physical pain. Chapter Three explores the way in which torture acts may function as language acts, and the necessarily public nature of such performative language. This chapter begins with a discussion of linguistic theories concerning pragmatics and performative language acts. Then, drawing upon textual examples from such Old English sources as Elene, Juliana and Daniel, this chapter examines how torture may be construed as a form of language, and how the performative nature of an act of torture articulates that act's context of power and politics in the culture at large

Shadow elimination and blinding light suppression for interactive projected displays

A major problem with interactive displays based on front-projection is that users cast undesirable shadows on the display surface. This situation is only partially-addressed by mounting a single projector at an extreme angle and warping the projected image to undo keystoning distortions. This paper demonstrates that shadows can be muted by redundantly-illuminating the display surface using multiple projectors, all mounted at different locations. However, this technique alone does not eliminate shadows: multiple projectors create multiple dark regions on the surface (penumbral occlusions) and cast undesirable light onto the users. These problems can be solved by eliminating shadows and suppressing the light that falls on occluding users by actively modifying the projected output. This paper categorizes various methods that can be used to achieve redundant illumination, shadow elimination, and blinding light suppression, and evaluates their performance. Index Terms — Shadow elimination, blinding light suppression, projector calibration, multiple projector displa

Shadow Elimination and Blinding Light Suppression for Interactive Projected Displays

A major problem with interactive displays based on front-projection is that users cast undesirable shadows on the display surface. This situation is only partially-addressed by mounting a single projector at an extreme angle and warping the projected image to undo keystoning distortions. This paper demonstrates that shadows can be muted by redundantly-illuminating the display surface using multiple projectors, all mounted at different locations. However, this technique alone does not eliminate shadows: multiple projectors create multiple dark regions on the surface (penumbral occlusions) and cast undesirable light onto the users. These problems can be solved by eliminating shadows and suppressing the light that falls on occluding users by actively modifying the projected output. This paper categorizes various methods that can be used to achieve redundant illumination, shadow elimination, and blinding light suppression, and evaluates their performance