A Photogrammetry-Assisted Methodology for the Documentation of Complex Stratigraphic Relationships

Abstract

At Tell Yunatsite, a prehistoric settlement mound located in the Upper Thracian plain of Bulgaria, stratigraphic relationships between archaeological deposits are incredibly complex. Such complexity then prompted our exploration into developing a new methodology for the documentation of complex stratigraphic relationships. Here, we present the results of a new photogrammetry-assisted methodology that was developed to compensate for the shortcomings of currently utilized stratigraphic documentation methods, such as the Wheeler-Kenyon box grid and the Harris Matrix. First, using a UAV drone, we produce a high-resolution photogrammetric model of the entire site. Second, with structure from motion photogrammetry, we produce 2.5D models of excavation units in stratigraphic succession. Finally, utilizing GIS and Blender (a 3D computer graphics software application), we digitize the horizontal extents of each archaeological deposit and “fill” the space between their successive surfaces (from top to bottom) until a faithful 3D model of each deposit is generated. These deposit models are then combined and rendered simultaneously to form 3D block models of the excavation units that may, in turn, be cross-sectioned in any direction to view stratigraphic relationships in virtual profile.

Narrating Ancient Roman Heritage through Drawings and Digital Architectural Representation: From Historical Archives, UAV and LIDAR to Virtual-Visual Storytelling and HBIM Projects

“…On the other hand, unmanned aerial vehicles (UAVs), commonly known as drones, help reduce the acquisition and survey times of structures that are difficult to reach from the ground, thus favouring the subsequent phases of 2D and 3D digitisation [5][6][7][8]. The data restitution and interpretation phases use well-established processes, such as the dense structure from motion (DSfM) and the restitution of as-found drawings from photogrammetric data, such as dense point clouds, mesh textured models and orthophotos [9][10][11]. Moreover, in recent years, interesting studies in the digitisation of built heritage have shown how HBIM (historic building information modelling), scan-to-BIM process and interactive forms such as virtual and augmented reality (VR-AR), allow professionals and visitors to have many more detailed and content-enriched digital data [12][13][14][15].…”