The Archaeology Data Service, with colleagues in the Visual Arts Data Service are pleased to announce the launch of the latest in their guides to good practice series: "Creating and using Virtual Reality: a guide to Good Practice" (Fernie and Richards 2002). This guide, published online at the end of 2002 is due for imminent release in paper form from Oxbow Books.
The Guides to Good Practice series provides authoritative support and guidance on how best to develop and implement projects in archaeology using digital technologies. Previous titles in the series cover aerial photography (Bewley et al 1999), excavation and fieldwork (Richards et al 2000), CAD (Eiteljorg et al 2002), GIS (Gillings and Wise 1997), and geophysics (Schmidt 2002). Though written principally to support the research community, the titles in the series have wide applicability in other sectors such as heritage managers and students, and to disciplines outside archaeology too. The guides are intended to allow expert practitioners to communicate with those who are already technically competent but perhaps less familiar with latest innovations in the field, or unfamiliar with the specific needs of digital preservation. This means that the VR guide is not so much a manual for those wanting to build their own VR models, but provides notes and advice from those already skilled in its development to those thinking of taking on new projects.
Virtual reality presents unusual archival problems for archaeology that are not often recognised. Though VR is often the most obvious public face of computing in archaeology, there is relatively little practical experience in how it should be archived or the standards which archiving may require. This is partly because VR is used as a blanket term to cover many different types of application, such as solid modeling, "bubble worlds" and collaborative virtual environments. Also, because it is often considered as a presentational tool alone, the life-cycle of virtual reality has tended to be shorter than for other types of archaeological data. Finally, the relative size and complexity of the models means that the work of documenting and storing them is more demanding than for less complex or smaller digital resources.
The new guide is aimed at a general audience across the Arts and Humanities, giving advice on all the different forms of data referred to as virtual reality. Thus, though technically very different, Virtual Reality Modeling Language (VRML) and its XML based successor "X3D" are discussed alongside QTVR panoramas and collaborative tools like Active Worlds. This broad definition is intended to reflect the ambiguity of the concept of virtual reality. The guide investigates the methods and techniques associated with each of these technologies, providing an overview of their likely system requirements and the implications that these requirements may have for users.
After introducing the range of technologies available, the guide provides support to those planning or commissioning a virtual reality project. This section focuses on the needs for different sorts of documentation, including not just the technical aspects of the project itself but the needs, expectations, and facilities of intended target audiences. Given the prominence of 3d reconstruction as a public access tool or educational tool for archaeology, the need to understand the user community is often greater than for other types of digital resources. This is a particularly acute problem because the diversity of formats and browsers required makes interoperability between the users’ computing platform and the virtual reality presentation unusually problematic. Developers need to understand not only the virtual reality as they envisage it, but the constraints imposed by the user community and the environment in which those users will encounter it. For example, even through they may derive from the same basic digital resource, a 3-d model delivered in a museum gallery with touch screen technology on a dedicated PC will be able to create quite a different impression from one delivered across the Internet into the home. The latter should be compressed to facilitate delivery and simpler to navigate by mouse and keyboard, while the former could be more ambitious.
Archiving virtual reality models and presentations is discussed in some detail, and the problems associated with it are explored. In some cases, it is easier and more useful to archive the fundamental data with which a 3-d model is built than the model itself. Thus, where images and 3d CAD drawings are put together to create a solid model, it may be easier to archive the images and CAD files with documentation of the process by which the model was created. The same is true of some types of panoramas where the virtual reality is stitched together from high-quality images. In other contexts, where the model is created from scratch, it may be simpler to migrate the model to an open standard like VRML, and from there into subsequent file formats. However, because "look and feel" are important to many VR projects, migration may not be capable of retaining the most significant properties of the models. In these circumstances emulation may be the most sensible route for long term preservation.
In other cases, where collaboration is dependent on real-time interaction with remote users and their own interactions with digital objects, preservation may have to take a different form. With conventional digital resources, the interaction between user and object is discreet and has little or no impact on other users. With collaborative environments, many users interact simultaneously and those interactions may impact others directly. Indeed, the simultaneous multiple-user interaction can be the most important aspect of the resource. This presents archival problems, as it is not possible to assemble all the relevant users to recreate those multiple interactions. Although it may not be possible to preserve the collaborative environment per se, it is possible to keep a record of the environment - a record of dialogue between users, the "chat-log," their avatars and so forth. This "preservation by record" allows subsequent users to play back the course of events in a virtual environment.
In each case, however, the guide stresses the need for clear documentation at the outset for preservation purposes and resource discovery metadata to ensure that the models can be discovered and used by others. The guide provides pointers to more formal technical standards and a documentation checklist.
The guide is aimed at people with some knowledge of virtual reality or those who may find themselves commissioning or managing projects that have a VR component. Perhaps the most useful section for those unfamiliar with VR is the long library of case studies that support the guide. These are as diverse as VR models themselves and include reconstructions of numerous historic towns and locales, virtual spaces where communities interact, and virtual art galleries where museum pieces are displayed in context. Notes on how to obtain necessary plug-ins and netiquette for the uninitiated are also supplied.
A list of available AHDS Guides to Good Practice include:
-- William Kilbride
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For other Newsletter articles concerning the use of electronic media in the humanities or CAD consult the Subject index.
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