Richard Bayliss ARCHAEOLOGICAL SURVEY and VISUALISATION

288 richard bayliss ARCHAEOLOGICAL SURVEY AND VISUALISATION: THE VIEW FROM BYZANTIUM RICHARD BAYLISS Abstract This paper will explore the relationship between the methodologies used in archaeology for recording buildings and landscapes and the development of computer visualisation technology, with specific reference to late antique and Byzantine archaeology. The principal aim is to highlight the applicability of visualisation technologies as the critical solutions to the presentation and investigation of survey data and reciprocally to demonstrate that meaning- ful computer visualisations benefit from a secure underpinning of archaeological survey data. My intention is to show that computer visualisation should not be seen solely as a vehicle for archaeological reconstruction but rather can be viewed as an integral part of the process of interpretation. The first of two case studies is the Anastasian Wall Project, a survey of a massive linear fortification in Turkish Thrace, which presented a series of practical problems both in terms of data capture and representation. The applicability of computer-based techniques for the integration and visualisation of various forms of survey data will be further investigated through the study of the Alacami, a multi-period Byzantine church in Cilicia, before some final comment is made on the current and potential roles of computer visualisation in Byzantine archaeology. Introduction: The Ethics of Visualisation For most of us, our knowledge of the role of computer visualisation in archaeology has been formulated by exposure to the high-budget animated sequences that are now an essential part of any respect- able television documentary. The sterile, polygonal and uninhab- ited computer-generated scenes experienced by the audiences of the early 1990s, have been replaced by deeply textured ancient envi- ronments occupied by realistic (or at least mobile) characters. This L. Lavan and W. Bowden (edd.) Theory and Practice in Late Antique Archaeology (Late Antique Archaeology 1 2003) (Leiden), pp. 288-313 archaeological survey and visualisation: byzantium 289 has had a tremendous impact on public perceptions and expectations of archaeology in general. The vital link between archaeological interpretation and the representation of an archaeological site is therefore increasingly under threat, as graphical ideals take precedence over historical reality. The pursuit of a perceived reality in computer visualisation has also in- evitably led to additional compromises in the historical and archaeological integrity of computer visualisation methodologies. Equally, computer visualisation in archaeology has developed with a pace that has effectively outstripped significant academic debate on the ethics and theoretical basis of its applicability.1 The awesome possibilities of computer reconstruction and visualisation techniques and the speed of their development have therefore initiated something of an abandonment of conscience over matters of authenticity and the ethics of definitive representation. In Alan Sorrell’s famously murky illus- trations of reconstructed landscapes, areas of uncertainty were ob- scured with either thick smog or a deeper gloom. Attempts to convey such uncertainties within virtual worlds or computer visualisations have thus far been limited.2 Although some are now actively encour- aging the abandonment of realism, recent publications on virtual archaeology clearly demonstrate that many others continue to seek its justification.3 To further compound the problem, techniques of visualisation have now achieved a level of complexity that is beyond the abilities of many archaeologists either to comprehend or to employ and the responsibility for their implementation and development has moved more firmly into the realm of the computer science and the graph- ics industry.4 Hence we tend to find that computer visualisation technologies are employed as an adjunct or by-project of archaeo- 1 For the key problems of archaeological visualisation see Miller and Richards (1995), Ryan (1996) and Eiteljorg (2000). The most active advocate of theory in archaeological visualisation has been Mark Gillings (see various references in bib- liography including work with G. Goodrick). My thanks to James Crow and Glyn Goodrick for their comments on the final drafts of this paper. 2 Sorrell (1981) and his reconstruction painting of 9th-11th century Con- stantinople in Talbot Rice (1969) 120. The exception is the work on hyperreality in VR, see Goodrick and Gillings (2000). 3 Forte and Siliotti (1997), Barceló, Forte and Sanders (1998) and various papers in Fisher and Unwin (2002). 4 This is demonstrated by the complexity and diversity of data acquisition and visualisation techniques outlined in Barceló (1998). 290 richard bayliss logical research rather than as an integral part. This marginalisation of archaeological research agendas has done much to exacerbate academic scepticism over the potential role of these techniques within ‘serious’ archaeology. Interestingly, this problem was recognised as far back as 1993, by the then departing Chairman of the Computer Applications in Archaeology (CAA) association.5 Those were the halcyon days of computer archaeology when geographical information sys- tems (GIS) were the answer to every archaeologist’s prayers and future archaeologists were to be afforded great benefits from full immer- sion within virtual worlds.6 Such utopian ideals have more recently diminished and while GIS has undoubtedly found its niche in archaeology, the status of computer visualisation and virtual reality (VR) is as yet unproven.7 This paper aims to introduce the concepts, techniques and ethics of computer visualisation to late antique and Byzantine archaeologists, through the critical discussion of two Byzantine-period fieldwork projects in which computer-based methodologies have formed an integral part: the Anastasian Wall Project and the Alacami Project. The context and surviving composition of these structures could not be more different: one, a landscape study of monumental linear engineering works surviving in deep forest, the other a highly detailed survey of a multi-period basilica on the edge of a Turkish town. The survey methodologies for both of these projects will be outlined and I will show how computer visualisations can be and should be derived from this primary archaeological data. Through the use of these case studies I will also emphasise the importance of ethical por- trayal in computer visualisation and at the same time show how such techniques can be employed as fundamental interpretative elements of a research programme. Finally, I hope this paper will demonstrate how effective results can be achieved using relatively straightforward techniques and software, allowing archaeologists themselves to adopt a more significant role in their implementation. 5 Reilly (1995). 6 Miller (1996). 7 For a critical look at utopianism in computer archaeology see Huggett (2000). archaeological survey and visualisation: byzantium 291 The Anastasian Wall Project By A.D. 400 the wealth and population of the Emperor Constantine’s new city on the Bosphorus was fast approaching that of Rome. As the population of the city expanded, so did the requirements and expectations of its inhabitants. This led to a proliferation of build- ing activities, which, in a mere 200 years, saw the construction within the city of a palimpsest of affluent public and private structures. The early 5th c. Theodosian Walls of the city separated populated Con- stantinople from its immediate hinterland and provided an enduring defence against would-be assailants. The deteriorating situation in the Balkans prompted the emperor Anastasius (491-518) to commission the construction of an additional, outer fortification, some 65 km to the west of the city walls. The Anastasian Wall is over 56 km long and traversed the hills of central Thrace from the Black Sea to the Sea of Marmara. It was undoubtedly a massive achievement of engineering, requiring substantial human and financial resources, intended to protect the city and its hinterland from all but a naval assault (fig. 1).8 The Anastasian Wall Project began in 1994 with the aim of pro- ducing a record of this great early-6th c. outer fortification. How- ever, this detailed survey was part of a broader strategy, in which study of the city’s hinterland would contribute to a fuller understanding of the city itself. In addition to the survey of the Wall, therefore, project researchers began an investigation of the water supply system for the Byzantine city, extensive evidence for which survives in the vicinity of the Wall. The pre-Constantinian water supply system was clearly inadequate for the sustenance of the rapidly expanded city, and thus a new system was begun under Constantius II, which within a hundred years probably rivalled that of Rome as the most extensive aqueduct system in the ancient world.9 The main branch of the system—the completion of which was celebrated during the reign of the emperor Valens—was a staggering 250 km long, nearly three times the length of Rome’s longest aqueduct, the Aqua Marcia. The remains of this endeavour survive in the dense forests of Thrace 8 The principal publication on the Anastasian Wall is by Crow and Ricci (1997). Fieldwork reports have appeared from 1995-2001 in the Bulletin of British Byzantine Studies and Anatolian Archaeology. See also the website http://museums.ncl.ac.uk/ long_walls/index.html.

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