Reconstructive archaeology: In situ visualisation of previously excavated finds and features through an ongoing mixed reality process

Abstract

Archaeological excavation is a demolishing process. Rather few elements outlast extractive operations. Therefore, it is hard to visualise the precise location of unearthed finds at a previously excavated research area. Here, we present a mixed reality environment that displays in situ 3D models of features that were formerly extracted and recorded with 3D coordinates during unearthing operations. We created a tablet application that allows the user to view the position, orientation and dimensions of every recorded find while freely moving around the archaeological site with the device. To anchor the model, we used physical landmarks left at the excavation. A series of customised forms were created to show (onscreen) the different types of features by superimposing them over the terrain as perceived by the tablet camera. The application permits zooming-in, zooming-out, querying for specific artefacts and reading metadata associated with the archaeological elements. When at the office, our environment enables accurate visualisations of the 3D geometry concerning previously unearthed features and their spatial relationships. The application operates using the Swift programming language, Python scripts and ARKit technology. We present here an example of its use at Les Cottés, France, a palaeolithic site where thousands of artefacts are excavated out of six superimposed layers with a complex conformation.