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Comparative Content Analysis of Virtual Environments Using
Virtual Reality Applications Research Centre, University of Teesside, Borough Road, Middlesbrough, TS1
Our understanding of Virtual Reality (VR) as a communications medium is not as well
developed as the technologies of VR themselves. This paper presents the practical
application of a content model of VR, which aims to alleviate this problem. First of all a characterisation of the aesthetics of VR is put forward against which the practicalities of the content model can be judged. Then, the content model, based around Perceptual Opportunities (POs), is briefly outlined before it is illustrated in greater detail through its application to the analysis of five Virtual Environments (VEs), two drawn from traditional VR and three from computer games. From the separate analyses a comparative content analysis is presented which makes surprising links between apparently diverse VEs and allows some insights into VR itself to be drawn. The conclusions document current and future research into POs in particular and VR theory and its practical applications in general.
1. Introduction If we take an inclusive definition of VR to variously refer to desktop and high end VR, 3D computer games, Hybrid TV, and so on, it seems that VR will constitute one of the principal communications media of the new century. We could predict with some confidence that such interactive 3D virtual systems will be to the 21st century what the moving image was to the 20 th and will significantly change the way we view ourselves and the world around us.
However, for a variety of reasons, our understanding of VR as a communications medium is not as well developed as the technologies of VR themselves. Thus our ability to construct effective, user centred virtual environments (VEs) is still very much reliant on individual knowledge and experience. The problem with such knowledge is that it is not generic and does not easily allow us to apply it to other applications areas particularly within the inclusive scope of VR we are taking. In the field of computer games Church recognises just this problem when he calls for a set of “formal,
design tools” (FADTs) for the analysis and comparison of games as well as their design (Church,1999). Church’s FADTs are perhaps best viewed as a characterisation of the aesthetics of VEs. In other words as an attempt to, first of all, characterise and then design for the particular pleasures that interactive media offer. His characterisation consists of intention, perceivable consequence and story. Murray characterises the aesthetics of interactive media as agency, immersion and transformation where agency can be seen as consisting of both intention and perceivable consequence (Murray,1997). Immersion is understood as the willing suspension of disbelief in the fact that the environment is mediated. In the VR world immersion is used to refer to the embodying interface, the technology, while the term presence is used to refer to the mental state of accepting a virtual environment as real and we will use this terminology. From both aesthetics we can
derive a useful working characterisation of the particular pleasures of VEs:
• Agency – on being able to set goals, plan their attainment and be rewarded by sensing the VE change appropriately as a result of the actions taken.
• Narrative potential – the sense that the VE is rich enough and consistent enough to facilitate purposive experience that will allow the user to construct her own narrative accounts of it.
• Presence – the perceptual illusion of non-mediation (Lombard and Ditton,1997).
• Transformation – temporarily becoming someone or something else as a result of interacting with the VE.
Of course there are other possible characterisations of the aesthetics of VR but these will suit our purposes for the present. One question we would like to ask ourselves is how do we go about designing VEs so as to generate and exploit such pleasures?
POs are a generic model of the content of VEs which perform the kind of practical, generic role that Church calls but in the wider context of VR in general (Fencott,1999a). The content model for VEs functions something like the syntax and grammar of a natural language. It is based on the aesthetics of VR and focus on the fundamental communicative properties of VE content. POs also provide a generic structuring mechanism that is used to relate communicative components into a coherent whole. In Fencott (1999a) the content model is illustrated with references to a virtual model of the historic, water balanced cliff lift at Saltburn by the Sea in the North East of England. The model is a virtual tourist site developed for the Saltburn Improvement Company (Fencott,1999b).
In this paper the content model is applied to the evaluation of a range of VEs from both the VR and the computer games worlds so as to demonstrate that apparently unrelated VEs do indeed have commonalties of structure and content. These analyses in terms of POs can then be used to relate particular VEs to the general aesthetics of the medium as given above. This process is then continued when the analyses of individual VEs are compared and contrasted to see what further we can learn about them collectively and about VR in general.
Section 2 of this paper introduces POs as a content model for VEs. In section 3 Perceptual Maps are introduced as a structuring mechanism for POs. In section 4 a number of VEs from both traditional VR and the games industry are evaluated in terms of POs. In section 5 a comparative content analysis of these VEs is given. Finally, in section 6 other current work utilising and building on POs is referred to.
2. Perceptual Opportunities POs are a content model for interactive media and VEs in particular and were initially developed to assist in the teaching of VE design (Fencott,1999a). The model addresses the psychological and communicative qualities of a VE that seek to gain and hold the visitors’ attention through the human senses and perceptual system. The perceptual is about details that arise naturally from the spatial world and involve the visitor both consciously and unconsciously. The latter is very desirable because there is something very fundamental about unconscious involvement - accepting a place or activity without thought.
The content model we will introduce in this section can be used as both a design tool and a model with which we can construct experiments into the nature of users interactions with VE of all genres. It is very often the case that the overall goal of a VE will not be a particular place or object. Nor will the means of achieving that goal be explicit and concrete but will require the user to explore, formulate and solve problems, and generally progress through such activities towards completion of the VE - in the various forms that completion might take in this context. The keyword here is opportunity. The art of VE design is surely to provide users with carefully structured opportunities to allow them to explore, strategize, and generally feel some sense of control over what they are doing.
Content for VEs is thus the appropriate configuration of a set of POs allowing the visitor to accumulate over time a set of experiences, which maintain a sense of purposive presence. We will call such a configuration a perceptual map and discuss its structuring mechanisms after a detailed discussion of POs themselves. Creative design in VEs is thus concerned with attracting visitors' attention through patterns of mediated stimuli, which will achieve purpose if the visitor perceives and responds to them as the designer intended. A discussion of a wide range of material which has been influential in developing the theory can be found in (Fencott,1999a).
Figure 1. Characterising Perceptual Opportunities
The PO theory consists of a set of syntactic categories (figure 1) which can be seen as attributes of any object that might conceivably be placed in a VE. These attributes specify the way in which the object is intended to function as part of the overall communications package of the VE. The syntactic categories into which perceptual opportunities can be characterised identify their role in achieving purpose and it is their planned interaction that gives us the overall structure we are looking for. A perceptual map is thus a loosely grammatical structuring of POs which seeks to ensure that users construct an appropriate temporal ordering over their attentions and activities within the VE. Together POs and associated perceptual maps are a means of specifically designing agency and narrative potential into VEs.
The figure above shows how the range of perceptual opportunities may be broken down into three principal forms, each of which will be defined and investigated in the sections that follow.
2.1. SURETIES Sureties are mundane details that are somehow highly predictable - their attraction is their predictability. They arise directly from the architecture of the space and are concerned with the logic of the environment unconsciously accepted (Spinney,1999).
The following quote gives an insight from photography into the nature of sureties in VEs:
Hence the detail that interests me is not, or at least is not strictly, intentional, and probably must not be so, it occurs in the field of the photographed thing like a supplement that is at once inevitable and delightful. (Barthes,1984) Sureties are thus concerned with vection, ego scale, perceptual noise, distance, limit, self image, past, physics, and so on. They are often given by unremarkable objects such as lamp posts and street furniture which never the less support the above. This is important because, for instance, sureties for distance, as people would normally recognise them, are largely absent in VEs. Distance or depth sureties are very difficult and encompass loss of colour with distance, depth of focus, loss of fidelity, small objects disappear faster with distance than large ones, and all this decreases with decreases in display resolution.
This is also true for the scale of objects and one's own avatar. Space should not be static and sterile but dynamic and messy. We are used to the real world being like this so it helps if virtual ones are as well. VEs and mess/clutter don't however go naturally together. A useful aphorism is that in interacting with the real world we are trying to make sense of too much information but that in interacting with VEs we are trying to make sense of too little. Perceptual noise refers to this apparently redundant clutter. Simple objects such as street furniture can often variously support vection, ego scale, distance cues, perceptual noise and so on.
Sound is an important spatial surety in reality and greatly supports presence. It gives important information about the nature and scale of the space that we are currently experiencing, i.e. small, large, inside, outside, etc. (Anderson,1999). We are very susceptible to reflected sound as sureties in this sort of way. We are not very good at locating objects accurately in 3D space based on the sounds emanating from them. The nature of sound in VEs means that sound can be used for atmosphere etc. but not as well for spatial and directional cues. This depends on the nature of the sound system itself being used, i.e. stereo, surround sound, and so on.
Sureties are closely allied to the fidelity and immersiveness of the embodying interface in that both seek to convince the visitor that the mediated environment is real.
2.2 SURPRISES The idea for surprises as perceptual opportunities came from the "appropriately designed infidelities" of Whitlock et al (1996) who used them for emphasis in virtual worlds and thus to precipitate conscious learning. In other words, non-mundane details that are not predictable but they do arise however surprisingly from the logic of the space consciously accepted. Surprises therefore are designed to deliver the purpose of the VE by allowing visitors to accumulate conscious experience from which narratives can be constructed after the visit.
Surprises can be: implausible but beneficial or totally plausible but unexpected, and there are three
• retainers POs can be both sureties and surprises depending on the context in which they are offered - there is no mutual exclusivity between them. Some things will be more or less surprising than others, eg. limit sureties may sometimes be perceived as choice points, the animated vehicles are attractors at a distance but retainers when the visitor gets close enough to take a ride.
2.2.1. ATTRACTORS Attractors are POs which seek to draw the attention of a visitor to areas of interest, retainers, that will deliver interaction sequences whose collective aim it to satisfy the high level objectives of the VE.
Attractors are the means by which users are tempted into setting goals for themselves. It is thus important that major attractors are associated with perceptual opportunities, retainers, which reward users/visitors with things to do, remember, excite, puzzle, etc. and which will allow them to feel they have attained the goal they set themselves as a result of the attractor. To aid in these further perceptual opportunities, connectors, should be carefully designed to allow visitors to formulate plans to achieve the gaols they have given themselves using available connectors, such as axes and choice points. All attractors rely on peoples' natural curiosity and their prime purpose is to draw people into areas of conscious activity, called retainers, which are designed to deliver the main purpose of the VE. See the section on perceptual maps for more details on this.
Attractors will often be seen or heard from afar. Animation is a particularly successful form of attractor in that it makes things stand out because of our deep-rooted perceptual affinity for movement.
However, attractors may be static and quite local. Doorways as both entrances and exits are examples of static attractors as are partially obscured objects and spatialised sound.
Attractors may be characterised according to the reasons they draw attention to themselves: