Building blocks between past and present: Perspectives from a holistic 3D GIS-based intra-site excavation archive

• Single source archive for all data domains of past and present excavation data. • Large scale retrospective photogrammetry from separate excavation campaigns. • Incorporation of architectural reconstruction suggestions within a 3D GIS framework. • Comprehensive, real-time access to all available data for reflexive decision making. This paper summarises the development and showcases the uses of a 3D GIS-based tool used by the Keros Project in our work at the Early Bronze Age site of Dhaskalio, Keros. While reflexivity and born-digital tools were built into the design of the more recent 2016–2018 excavations, the earlier 2006–2008 seasons were limited to the techniques available at the time. This has led us to address how to appropriately integrate older non-natively digital excavation material into an extensive 3D environment in a way in which specialist and artefact data, stratigraphic information and architectural material can appropriately be analysed together and made accessible to team members in a single environment. The extrapolation of photogrammetric models and orthomosaics from archival excavation photos from the 2006–2008 seasons, and incorporation of 3D finds and specialist data has been a key challenge. The synthesis of old and new data from a project archive based on disparate sources in such a 3D environment has offered many benefits: first, a contribution to the role of reflexivity in excavation practices and site interpretation, and second, a better comprehension of the site overall, especially from an architectural perspective. In particular, bringing together 3D models of building remains which had been backfilled, and were thus inaccessible to those working in the most recent excavations, has been invaluable to our understanding of the site. Furthermore, such work has facilitated the production of new data in 3D reconstructions of the different occupation phases. This paper addresses some of the methodological and theoretical issues faced when attempting to incorporate such diverse data into a single access point, in particular with reference to 3D data, in the hope of continuing a dialogue on best practices for long-term single project archives in a period of increasingly born-digital data.