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Section 6: Archiving Virtual Reality Projects#

6.2 Digital archiving strategies#

Back-up is the familiar task of ensuring that there is an emergency copy (or a snapshot) of all data held separately in case of damage to the original data (by accident or through a disaster). For a small project this may mean a single file held on a floppy disk or on a network; for a larger project or dataset it may involve complex procedures involving disaster planning, with fireproof cupboards, off-site copies and daily, weekly and monthly refreshing. Such back-up strategies are important in the lifespan of the project but are not the same as long-term archiving of the data.

Digital archiving does not rely on the preservation of a single disk, tape, or CD-ROM. The essence of digital archiving lies in one of three strategies (Beagrie and Greenstein 1998):

  • Migration of information from older hardware and software systems to newer systems
  • Emulation of older hardware/software systems in newer systems. This is technically challenging and becomes increasingly difficult as current technology becomes ever more remote from the original systems employed
  • Complete preservation of old hardware and software systems. This very high-risk strategy should only be considered as a short-term measure as it depends on retaining the skills and resources needed to maintain and run the original system.

Data migration is the strategy recommended for most applications. Where standard data formats are available (such as ASCII text, TIFF images or VRML) data migration is successful in preserving data for future use. Where data cannot be migrated or the original 'look and feel' is of substantial importance a strategy of either emulation or technology preservation may be justifiable.

The Guggenheim's Variable Media Initiative is of particular interest to artists working with virtual reality. This initiative is exploring preservation strategies for ephemeral media and for the Guggenheim's collections of Conceptual, Minimalist and video art. Artists, museums and media consultants are working together to consider the implications of 'storage', 'emulation', 'migration' and 'reinterpretation' strategies for artworks. The Case Studies include the 1991 interactive installation of black rod liquorice candy by Felix Gonzalez-Torres. Although not virtual reality, this is of direct relevance as it explores the significance of different preservation strategies and the importance of lifespan, physical appearance and meaning to the work.

6.2.1 Practical issues

No digital archivist can successfully preserve data that are not fully documented; with every strategy there is the potential for information to be lost. Detailed documentation (see Section 5) allows archiving strategies to be carefully planned and tested in advance. Digital data also need to be regularly managed. Archivists use data management tools (such as Electronic Document Management Systems) to inform them when files held in deep storage facilities require active intervention. These are usually databases that, ideally, flag dates and automatically inform the system manager when files need attention.

6.2.2 Data migration

Digital archiving generally revolves around a policy of controlled data migration. Archiving by this strategy involves four main activities: data refreshment, data migration, documentation and data management tools.

Data refreshment is the act of copying information from one medium to the next as the original medium nears the end of its reliable lifespan. Research into the lifespan of both magnetic and optical media has shown that the former can be safe for 5–10 years and the latter may survive more than 30. However, technology changes much more quickly and digital media are far more likely to become unreadable as a result of changes in hardware and software than through media degradation.

The process of data refreshment involves copying data to new media as technology evolves. For example, data collected on 3-inch Amstrad diskettes might have been refreshed on to 5.25-inch disks and again on 3.5-inch disks as computer hardware developed.

Computer software changes even more rapidly than computer hardware. Data files that have been created in the proprietary format of a particular software package may not be retrievable in future. The software company may change the formats used in subsequent versions of the package, or may cease trading and the file may not be accessible by software produced by other companies. Data migration is the act of copying data files from one format or structure into another. For example, copying a word-processor file into a newer format while maintaining its original content and appearance. In some cases, migration may offer improvements in access to information, for example migrating an old CAD file to newer versions might allow users to access the enhanced functionality of next-generation CAD software.

File formats that have been identified as international or open standards support the migration of data files into new generations of software. This is because the definitions for these formats are published (e.g. VRML'97 is published by ISO) and they are implemented consistently by different software manufacturers. File formats that have become industry standards, because they are widely used, generally allow files to be imported into other software (e.g. DXF is developed by AutoDesk). Industry standard file formats can be interpreted differently by the various software manufacturers, which can mean that a file produced in one package cannot be read in another. However, industry standard formats generally can be migrated if archival guidelines to use the basic export are followed (see Section 6.4).

Some software manufacturers develop proprietary file formats for use in their own packages. In some cases, the definitions for the formats are available for other manufacturers to use. But in other cases, formats are used by a single software manufacturer and no definitions are available for others to use (e.g. Superscape developed the SVR format and Sun have developed JXF). Such files can generally be migrated into the next generation of the software package in which they were developed. But data held in proprietary file formats is vulnerable and may be lost if the parent software package ceases to be available.

Successful data migration relies upon good documentation and careful planning, testing and execution to preserve the original data (Wheatley 2001). Data management tools help digital archivists to plan for the tasks involved while good documentation helps them to understand the structure of the data fully and how the different parts relate to one another. Of equal importance is the use of open or industry standard file formats which allow migration to be executed without data being lost.

6.2.3 Emulation

Emulation revolves around using current technology to mimic the original environment. The digital project data are archived together with the original software and operating system. Future use of the data may involve mimicking either the original software or hardware on current equipment. The aim of emulation is to re-create the look and feel of the original system. Emulation can be technically challenging and may become more difficult over time.

The use of emulation for digital preservation is a very new area and, although it may not be a practical strategy at the current time, it may be used more widely in the future. Successful emulation will rely upon detailed documentation of the system as a whole and careful planning.

6.2.4 Technology preservation

Technology preservation is akin to traditional museums and archive practice. This strategy revolves around preserving the original hardware and software on which the system was installed. Future use of the data depends on maintaining and running the original system. This becomes increasingly difficult with time as the skills needed to maintain or repair the system are lost. For this reason, technology preservation is a very high-risk strategy and should only be considered as a short-term measure for digital archives.

6.2.5 Virtual Reality

All three digital archiving strategies have relevance when archiving virtual reality. A migration strategy can be used for virtual reality developed using standard formats, for original data files, screen-shots and associated documentation. Where it is important to preserve the 'look and feel' of the original virtual reality, emulation may be appropriate. For virtual reality applications that are dependent on specific hardware and software, emulation may be the only option. Technology preservation is not sustainable in the long term.

Archiving virtual reality is developing with the technology. It presents technical challenges and it is difficult to predict future archival strategies. It is important to consider the lifespan of each project. Some projects involve research into new techniques and the virtual reality that is developed may have a limited lifespan. Other projects have a longer life-span. If researchers wish to preserve virtual reality for the future, the best strategy is to adopt standard formats.

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