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The Design of Virtual Environments with particular reference to VRML

Design into production

Preceding sections of this report have deliberately addressed issues which are at several removes from the immediate business of making a Virtual Environment. Here we approach more closely the transition from concept to project.

Some metrics of reality

An unspoken assumption in some discussion of VR is that its technological development is well advanced and that the path before it is unproblematic. We might almost think that VR is within sight of the goal of perfect replication. By contrast, we have emphasised that a VR world is a representation, not a reconstruction of reality. The only representation that would theoretically approach reality would be boundless in size and of infinitely small granularity, modelling the behaviour of sub-atomic particles! This is a practical problem, not a philosophical one, and an important one for education. Not only must those who are building models recognise the limits of the representations they build, but so must the academics and learners making use of them.

Items from a reality checklist

It may be useful to look at a few of the aspects of reality which could in principle be represented using computer models, and notice how only some are possible in VR or even simulation systems. We have tried where possible to describe these metrics in non-computer terms.
Extent and scaling
Height, depth, breadth
Position and movement
Location in three-dimensional space; translation, rotation, including non-linear velocities
Passive visual qualities
Colour: hue, saturation, value; transparency, translucency; reflectivity (matt, lustrous, shiny, gloss, part-mirrored); texture (surface texture, solid texture)
Active visual qualities
Light source type eg light bulbs, phosphor, lightning; colour of light; distance, direction and spread of light sources
Dynamics and dependencies
Free movement independent of all other objects; rigid fixing to other objects; able to penetrate some objects, not others; internal object constraints (degrees of freedom); dependent object constraints (within, outside, hinge, slide); hierarchical object constraints (eg. arm moves hand moves finger, and reverse: finger moves hand moves arm)
Physical qualities - passive
Mass, hardness, brittleness, flexibility, crystallinity eg. splintering on breaking
Isotropy and directionality
Insulating/conducting properties for heat, sound, electrical current etc.
Physical qualities - active
Emitting heat and other forms of radiation
Textural qualities
Fluffiness, cloudiness
Tendencies to fall, continue along a trajectory, change colour, decompose, grow, subside, disperse, cool, lose or gain moisture, expand or contract
Animal behaviours and propensities
Human behaviours and propensities
Atmosphere: colour, opacity, humidity, air currents
Responsive sounds
When moved eg. scraping; when struck eg. thud; when squeezed eg. escaping air
Autonomous sounds
eg boiling water, sounds of animate creatures

Even this brief list indicates many aspects of reality which are currently difficult to model in VR systems (together with others which are widely available). Importantly, VR systems have tended - by contrast with various kinds of simulation - have tended to model passive visual qualities, rather than those of activity, behaviour and process.

Before embarking on VR...

Up-to-date technical tutorials can provide advice on the practical steps necessary in order to undertake a VRML project. Here we offer broader questions which should be asked when embarking on a project.

Is the project enhanced by 3D?

Clearly a fundamental issue, this is not always easy to answer. Some help may be provided by the following questions:

Cost benefit

Can you justify the following requirements in relation to any expected gains?

Perception and cognition

In this report we have commented on the possible dangers of replacing abstract and symbolic forms of knowledge with those which are more direct and concrete.

Designing the world - making the most of 3D

Designing the world - practical constraints

Many of the constraints on VRML models at any given time are contingent on particular versions of software - things which are problematic one month are easily solved the next. However, there are some general guidelines which are likely to remain valid: Some simple steps which may be taken include:

Designing the world - managing the process

The design of a VR world can be, and should be, almost as difficult as real architectural design. Indeed, as modelling and modellers become more sophisticated, their construction will increasingly resemble architecture (though not necessarily visually). For example, as third-party libraries become increasingly available, there will be problems with consistent quality and maintenance. Likewise management issues will become important as model-building is farmed out to large teams, some of them sub-contracted. And issues of control and negotiation will arise as worlds are connected to each other and virtual worlds come to be seen as public spaces.
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