Hypertext: A Practical Application
Archaeologists are interpreters who untangle the mysteries of the past and present it to the public. Traditionally the site report, the book, the museum display and model have been used, today the computer can be added to the list. This paper will discuss the use of computer based visualisations incorporated into a hypertext site tour as part of a project examining the surface and underground archaeology of a 19th century lead mine at Cononley, North Yorkshire. What are the practical and theoretical problems encountered and how can this be overcome to allow a wider audience access to knowledge, and how will this evolve in the future?
Interpretation, presentation, three dimensional visualisation, hypertext, practical application, navigation, disorientation, interactivity, narrative building, future developments.
Archaeologists have a duty to explain what they are doing and why
(Renfrew & Bahn 1996 p.535)
Archaeologists are collectors of complex data, interpreters who untangle the hidden meanings of piles of stone, broken pots, and the graves of long forgotten people. How do we then present this interpretation? Traditionally the site report, the book, the museum display and model have been used, today the computer can be added to the list.
In the case of a project examining the surface and underground archaeology of a 19th century lead mine at Cononley North Yorkshire what was required was a media that would effectively:
7 Present the history and archaeology of Cononley Mine.
7 Introduce the viewer to the surface and subterranean mining landscape.
7 Increase the accessibility to underground archaeology.
7 Introduce the viewer to the general concept and complexity of mining archaeology.
Displaying and Explaining the Underground Landscape.
To effectively understand the underground landscape required a suitable visualisation media. Traditional two-dimensional representations in the form of the plan and section were not an ideal solution, as they require experience to effectively interpret them. The problem of how to describe and portray the full three dimentional complexity of the subterranean landscape is not just a problem faced by archaeologists but also by mining engineers, and cave explorers. With the advent of three dimentional computer modelling it is now possible to generate and explore three dimentional representations, allowing a much wider audience to visualise and explore three dimensional hidden landscapes.
For this project the solution was to use cave-modelling software developed by cavers for cavers in order to aid the recording, understanding and exploration of caves. Although written mostly by professionals, the applications are designed for use by enthusiasts. The result is that for the most part the software is user friendly with simple data input interfaces, which mimic the form of a cave surveyors notebook. A second distinct advantage is that as these programs are aimed at the non-professional market they are designed to run on very modest computer resources and are also available as either shareware or freeware.
Using Cave Surveying Software
A three dimensional model of the accessible workings was constructed from compass and tape survey data collected underground. This proved the effectiveness of the software, it was then decided that a model of the whole mine would be a very useful way to illustrate the complexity of the site. This is where a problem occurred, as most of the software is designed to only take data in the form of direction, bearing and inclination. Accurately converting a flat two-dimensional representation of the mine into this kind of data posed a challenge. Co-ordinate data in the form of a 12 figure grid reference was collected for each change of direction or feature. To convert the grid references into the distance and bearing data required by the plotting software an Excel spreadsheet was designed, which has been named Co-Ordinate Converter and was used to build a model of 7.8km of mine workings in less than 3 working days.
The Problem with Computer Models
Having stated that computer models represent a better way to display and visually explain the underground landscape they are not without problems. How we perceive spaces and representations of spaces is fundamentally linked to our awareness of our location. If we can link our location back to a fixed, familiar origin or viewpoint then we know where we are. If we lose that link we become disorientated and lost (Cohen 1996). This is effectively what happens when an audience unfamiliar with viewing a three dimensional computer image zoom into the model, they soon lose that cognitive link back to a point of origin, in this case the view of the whole mine. To test the effectiveness of the model it was shown to members of a mining history society, familiar with the complexity of the underground landscape. An important lesson was learned from the stunned silence that filled the room. Even experts have difficulties understanding computer-generated images.
How To Present the Surface Archaeology
The surface archaeology of this site is mainly composed of standing structures and earthworks. These features could have been presented in a conventional paper based report but the surface remains cannot be fully explained and interpreted without reference to the underground features. To fully investigate this site it is therefore necessary to integrate the surface and underground remains.
How to integrate the Surface and Underground Archaeology
How to present this complex relationship required a particular solution. A most effective way to describe a complex unfamiliar concept is by combining pictures with a minimal but focussed amount of text. Images are a vital part of archaeology and it is important to realise that they can communicate information without the constraints of language (Martlew 1992 p.352). It has already been realised that the application of computer-based approaches can be of great use to archaeologists. The computer allows the storage of many more images than would be practical in a conventional book and indeed some graphic representations such as the model of the underground workings are not easy to reproduce in a traditional book format.
For the purposes of this project it was decided that the best way to present an integrated tour of the surface and underground archaeology lay with an interactive hypertext presentation.
What is Hypertext?
Computerised presentations are now familiar objects; the web site, the CD-ROM, the information kiosk. But what is hypertext? Hypertext is a conceptual combination of data combining text, still images, moving images, sounds and if we had suitable interface technology, smells, and physical sensations. In many senses hypertext could be considered as the natural evolution of the book in the same way that television could be considered as an evolution of radio, it has all the familiar features plus additional ones not previously possible. Television today is very different to radio but initially it was considered that television represented little more than radio with pictures, why?
Initially its potential was unknown as was its survivability. Therefore to encourage public acceptance it had to mimic aspects of radio and also the cinema, familiar and accepted entertainment and information mediums. A similar analogy is needed to effectively understand a hypertext presentation, in its current formative stage; it has to mimic a familiar concept such as the book. In many ways, it is like a book but with a more fluid structure.
The book is a static with the narrative following a fixed linear format;
hypertext is dynamic, allowing each viewer to explore the information in a different way, assembling their own alternative narratives providing more opportunities for interactivity and engagement (Hodder 1999 p.126).
The site tour has been developed using Microsoft Powerpoint. This is part of the Microsoft Office suite and is therefore easily available. Powerpoint was developed for business users and it is designed to replace slide and overhead projectors. This tour is set up like a slide show and is interactive in that the viewer has to do something for the slide to change, and they also choose what to look at next (within certain constraints).
The problem with hypertext is the lack of structure and the viewer can become lost and disorientated. While hypertext remains a new-ish concept its potential and fluidity is constrained by the need to present information in a familiar format. To avoid this disorientation phenomena, most hypertext documents mimic the hierarchical structure of a printed book. Index, chapter, page and paragraph are all represented as familiar structural elements but these elements can be accessed and interacted with in an infinitely flexible way. In hypertext, it is possible to build in many links, which allow the random browser to build an almost infinite number of alternative narratives (Woolley 1992 p.151-165). But without careful planning this can degenerate into chaos.
When we consider that the growth in the use of IT prompted the pessimistic prophesy that, The whole concept and nature of the book may be outdated (Uko 1992), it is clear that the book is still with us, but that the concept of the book is evolving within a computer environment.
In this example beyond the title page the tour runs from a central menu or main index. From here three main themes are explored:
1. General information A brief introduction to the site and its history.
2. The Surface Archaeology this is the largest section of the tour and operates from a series of hierarchical pictorial indexes. The first is a plan of the area with shaded zones which with a mouse click act as hyperlinks to either a short 2-3 slide tour of that area or a further more detailed plan, which againuses hyperlinks to bring up a slide or series of slides.
3. The Underground Archaeology this section again works from a pictorial index clicking on a name takes you that part of the mine. Three sections of the workings can be explored and all are presented in a similar format. A 3D representation of the section of the mine is accompanied by thumbnail photographs with arrows indicating where on the model they relate to. Clicking on the thumbnail brings up a slide with the full size picture plus explanatory text.
Each tour is composed of a slide or series of slides. To make it a true hypertext document sideways links between the tours are provided so that it is possible to link between the surface and underground sections. From individual slides there are also links to a glossary. Some terms are explained visually with text and pictures from other sites, this allow the viewer to not only understand the term but also to be introduced to intersite variation.
To maintain viewer interest the tour is designed so that generally it is possible to escape back to the main menu in less than four steps. Navigation deliberately mimics the form of a website with hyperlinked text, action buttons, and thumbnails.
Hypertext has proved to be a suitable media to present a site like Cononley Mine but it has some limitations. As has already been indicated computer generated models can result in viewer disorientation, this is just as applicable to hypertext presentations. This has been prevented by the provision of hierarchical indexes and hyperlinks with the minimum number of steps back from a slide to the main index. Maintaining viewer interest is vital and the solution has been to design a tour that requires action from the viewer before text or pictures appear or before the slide can be left, this will affect different users differently. Interest and a sense of anticipation are generated by the use of thumbnail pictures in the indexes and animated graphics on individual slides. To some users the need to do something will be irritating. This irritation factor is just as important as irritation induces involvement because it draws in the user who is inevitably curious or even infuriated when only part of the information has been revealed. After pressing a few buttons their irritation becomes interest and curiosity. To maintain interest the navigation button is located in a slightly different location and form on each slide forcing the viewer to visually scan the whole slide to find it. An additional advantage of this aspect of the design is that it allows viewers to advance at their own speed. Everyone reads text and interprets images at different rates so giving the viewer full control over the slide transition aims to prevent boredom.
The Tour has been tested on a number of different computers and certain very important facts were noted. The rate at which the slides load and animations run varies from system to system. Screen size affects the size and readability of text and so text should be designed so that it is readable on a small as well as a large monitor. Different monitors will display colour differently, therefore the colour of text and backgrounds to text need to be chosen carefully.
This should be all very obvious and common sense but also easy to overlook.
Hypertext has the potential to communicate complex archaeological information. It has the potential to present information in new formats. However it is currently constrained by the need to present information a familiar format in this case mimicking the book. Hypertext presentations can be produced with modest computer resources.
Future developments are hard to predict but we should see hypertext evolve away from this constrained book like structure, and this should allow the insertion of more text based data and therefore greater intellectual depth. The fluid form of hypertext will allow the inclusion of such data without the exclusion of non-expert viewers, because hypertext allows the viewer to build their own alternative narrative, the inclusion of different levels of data includes rather than excludes potential audiences. This will allow the production of information for all within one document thus realising the true potential of hypertext.
Cohen, G. 1996: Memory In The Real World. Hove: Psychology Press.
Hodder, I.1999: The Archaeological Process: An Introduction. Oxford: Blackwell.
Martlew, R.1992: The Implications of Large Scale Image Storage for Primary Archaeological Research. In P.Reilly and S.Rahtz (eds) Archaeology and the Information Age. London: Routledge.
Renfrew, C. & Bahn, B. 1997: Archaeology: Theories Methods and Practice. London: Thames & Hudson Ltd.
Uko 1992 In P.Reilly and S.Rahtz (eds) Archaeology and the Information Age. London: Routledge, (Preface).
Woolley 1992: Virtual Worlds: A Journey in Hype and Hyper Reality. Oxford: Blackwell.
For More information on the Interactive Tour of the Underground and Surface Archaeology of Cononley Mine and other work by the author