In use in archaeology there is a wide range of surveying techniques including 3D modelling, laser scanning, rectified photography, panoramic imaging, and photogrammetry. They can offer great accuracy fast, but they also produce large data files, which require expensive and sophisticated hardware and software in order to view and post-process them. Depending on the size of the archaeological site that needs to be surveyed, a large amount of data can be produced and data of different types, e.g. .obj (meshes), .jpg (photographs), .ptx (registered point clouds), .avi and .mov (film/flythrough). Archaeologists need to deposit this type of data in ‘trusted’ digital repositories where files are securely preserved, curated, and made permanently accessible.

Digital repositories dedicated to the archaeological sector have hosted and promoted standards and guidelines for best practice in the creation, description, preservation and use of archaeological information, so much for the benefit of the archaeological as the wider research community. They highlight the metadata required to record these processes, and the datasets produced at different stages that can be selected for archiving.

Nevertheless, the abovementioned standards and guidelines tend to focus on technical environment metadata, i.e. a description of a given 3D object’s file format as well as the software applications, operating system and hardware needed to make the 3D object usable. They thus miss information about the creative design process. As a result, they omit the virtual reconstruction paradata needed to be stored. Moreover, there is a large volume of digital archaeological outputs (hybrid digital objects) dating from around the beginning of the 21st century that are already becoming obsolete because of the recurrent technological changes. These hybrid digital objects are usually deliverables of research projects investigating archaeological remains through virtual representation, notwithstanding their associated context. There is a pressing need for digital preservation standards that can include those as well as digital archaeological outputs that are currently being produced.RI Fig 1 Panagiotis Papageorgiou

Hybrid digital objects are 3D objects that contain more than just a creative artefact and also have scientific metadata and virtual reconstruction paradata attached to them. As a result, not only can we not determine a definitive digital preservation strategy for archaeological data, but we also need to discover which one, or even combination of them, applies better to digital objects under the risk of obsolescence. Therefore, there is a need to focus on near-obsolete virtual reconstructions for which, at worst, there is no provision of preservation.

However, just having access to a stored digital file, e.g. archaeological virtual reconstruction, without its accompanying metadata/paradata is not enough. Hence, effective digital preservation occurs only when the provision of access to an obsolete digital file is complemented by the required metadata/paradata to understand what it represents and how it was created, respectively. In the case of virtual reconstructions, information about the creative design process is required to support the scientific authenticity as well as the repeatability of, often, particularly expensive, and difficult to reproduce proprietary processes, i.e. only repeatable within a specific software package, with access to the archaeological decisions made at that specific time.

RI Fig 2 Panagiotis Papageorgiou

This PhD thesis therefore investigated the following question: “What would be an effective strategy for the preservation of archaeological virtual reconstructions, as hybrid digital objects?”

The overall aim of this PhD programme was to provide a framework for evaluating the effectiveness of cloud-based emulation for preserving obsolete archaeological virtual reconstructions. The importance of this research lies in enabling designated communities to have a set of tangible evaluation criteria for archaeological virtual reconstructions. It achieved this through a series of rendering case studies to assess the applicability of existing emulation-based preservation frameworks for hybrid digital objects. Through the results of rendering case studies, the real practical application of the final framework became apparent. Then recommendations were made on evaluation criteria for archaeological virtual reconstructions. The research culminated in determining if cloud-based emulation could be employed to effectively preserve obsolete virtual reconstructions from the archaeology domain. Guidelines and test results coming from this work are of great benefit to the archaeological community, and contribute knowledge to other research communities, specifically those interested in similar data types/3D reconstructions.

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