CAA Conference

The main objective of our research is to understand possible relationships between the form and function(s) of archaeological artefacts, by developing a new methodology based on Reverse Engineering processes - i.e. 3D scan, quantitative data analysis and Artificial Intelligence techniques, in particular computer simulation. In addition, we intend to provide new data, as well as possible explanations of the archaeological record according to what it expects about social activities and working processes, by simulating the potentialities of such actions in terms of input-output relationships. Our research project focuses on the Neolithic lakeside site of La Draga (Banyoles, Catalonia). On the one hand, this presentation aims to provide a clear overview and description of the main guidelines used to capture and process 3D digital data of several wooden artefacts. On the other hand, to present the use of automated and semi-automated surface feature extraction for use-wear analysis, as well as preliminary computer simulation tests using Finite Element Analysis to study specific physical and mechanical issues and therefore try to determine possible functions of these same artefacts. Furthermore, we aim to reuse and to repurpose these 3D digital models in conservation monitoring, preservation, digital archives and other future researches.

This paper highlights the potential for the use of 3D microscopy for the study of archaeological materials. A review of current technologies in 3D microscopy is presented which higlights differences in how 3D data is generated by these systems. A case study showing how laser scanning confocal microscopy, with a sub-micrometer resolution, can be used to aid the recording and analysis of wear features on archaeological samples. In the field of lithic analysis, observation of wear is used to make interpretation of tool use and site function. The methods traditionally used by lithic specialists relies on personal interpretation of wear at tool edges. This study shows that laser microscopy can produce high quality images for visual presentation that also lend themselves to surface texture analysis. Roughness measurement algorithms can be applied to these 3D images and are used to differentiate tools used for different tasks; bringing quantitative method to lithic use-wear analysis. Other examples of the use of these technologies is presented along with a discussion of some methodological issues, including the use of casting when doing texture analysis.

Digital imaging techniques are increasingly being seen as an effective means of disseminating information to a world-wide audience and new technologies are beginning to be applied to the oldest of archaeological artefacts; lithic artefacts. A recent Nature paper presenting new evidence for the presence of hominins in northern Europe >0.78 Myr ago used supplementary material in the form of animated micro-CT volume renderings of lithic artefacts to support claims that they were humanly modified[1]. Further work on digital preservation and dissemination of ancient lithic technology led to the suggestion that virtual artefacts created using micro-CT might be "more useful to researchers than 2D drawings and photographs"[2]. The study by Abel and colleagues was designed to assess (a) whether micro-CT could capture the fine surface topology created during production of lithic artefacts and (b) if the technology could visualise missing parts of the production sequence. The results demonstrated the effectiveness of the technology for visualising artefacts and aiding analysis and interpretation. However, the study was limited to artefacts with very clear features that required little interpretation. Unfortunately, the Palaeolithic record is dominated by lithic artefacts that do not fall into this category and traditional visualisation techniques provide an interpreted view of the artefact. Traditional lithic illustration involves collaboration between an illustrator and a lithic specialist. The resulting drawings convey information about the artefact using accepted conventions, signs and marks. The specialist and illustrator decide which details of the artefact they wish to emphasise and whilst good illustrations are accurate they do not necessarily portray every detail of the artefact. Traditional illustrations are thus inescapably subjective and this stands in direct contrast to digital imaging techniques such as micro-CT. This contrast raises questions about the requirements that must be taken into consideration when commissioning visualisations of lithic artefacts. In this paper we explore the requirements of lithic specialists who commission visualisations of lithic artefacts. Considerations include: Production of a permanent recordVisualisation as an aid to analysisCollaborative workingDissemination of information Visualisations are a vital means of disseminating information to a wider audience. As some artefacts may be contested, especially where claims are being made for early evidence of lithic technology, there is an obvious issue of trust. Issues of time, affordability and access to equipment and expertise also play a key role in influencing which techniques are chosen. A combination of interviews and case studies were used to investigate how various visualisation techniques (traditional illustration, micro-CT, PTM) fulfil the requirements of lithic specialists. A new study was carried out in which a range of "difficult" artefacts were visualised using both traditional techniques and micro-CT. The results are discussed from the perspective of the end user, in this case the lithic specialist, and thus provide a novel viewpoint which should be of interest to lithic specialists, cultural heritage professionals and those engaged in developing digital techniques. [1] Parfitt S.A. et al. (2010) Nature 466, 229-233 [2] Abel, R.L., et al. (2011) Computers & Graphics 35, 878-884