Last modified: 2012-01-02
Abstract
The proliferation of terrestrial laser scanners on the market over the past few years has been accompanied by a rapid adoption of the technology by archaeologists. Its archaeological applications have been limited, however, with the growing number of arguments against 3D scanning as a practical means of documentation for archaeologists, preservationists, conservators, and architects. With the high price tag of some projects, terrestrial laser scanning is often claimed to be far more costly than traditional hand drawing, whereas others argue that scanning is much faster and cheaper when taking into account total field and lab processing hours. However, the detailed cost-benefit analyses necessary to support either side of this debate are lacking. To address this gap in publication, it is important to present cases where both full traditional drawing and laser scanning have been performed at one site, allowing the direct comparison of the two approaches. It is equally important to study a range of field conditions, because the effectiveness of terrestrial scanning or traditional hand drawing is also dependent on the extent and morphology of a site.
We present a detailed analysis of traditional drawing and laser scanning performed at two archaeological sites with different field conditions and research questions: the Mycenaean settlement at Kalamianos, Greece, and the Defiance House Ruin at Glen Canyon, United States. At the coastal site of Kalamianos, a recently discovered LH IIIB town has been studied since 2006 by the Saronic Harbors Archaeological Research Project (sponsored by the ASCSA, FSU, and Penn) through intensive survey, the manual illustration of architectural remains, and the terrestrial scanning of three well-preserved building complexes. Defiance House Ruin is a well-preserved Ancestral Puebloan cliff dwelling that has been subject to several stabilization and documentation episodes since the late 1950s. These efforts have become progressively important as visitation and erosion concerns increased dramatically with the inundation of Glen Canyon. The National Park Service has employed laser scanning in order to evaluate the suitability of such technology as an effective management tool for preservation documentation and cyclic monitoring in comparison to digital photography, hand-drawn scaled illustrations, and AutoCAD digitizations.
For both sites, we detail the costs of the teams and equipment necessary for traditional drawing and terrestrial scanning. We also consider the advantages and drawbacks of the data produced by the two methods. The 3D data sets are of course vastly richer than two-dimensional line drawings or photographs. However, the sheer immensity of a full-resolution point cloud is burdensome to process and manipulate, and it includes extraneous information which can obscure, rather than clarify, the most important features in a line drawing. We close with a discussion of vector extraction techniques for the rapid creation of digital line drawings from the large point clouds captured at both sites.