UAV photogrammetry for the protection of cultural heritage: methodologies, case studies, and applications

The use of UAV photogrammetry has significantly enhanced the geometric documentation of cultural heritage sites, by providing – in a cost-effective way – high-resolution image datasets for accurate mapping and 3D modelling, monitoring, risk assessment and digital preservation. This paper explores the methodologies and applications of UAV photogrammetry, emphasizing its growing role in protecting endangered archaeological and historical sites. The paper begins by outlining UAV photogrammetry methodologies, with a focus on data acquisition (including both imagery datasets and ground survey), image matching procedures, image orientation and sparse reconstruction through Structure from Motion (SfM) processes, multi-view stereo pipelines for 3D point cloud creation and 3D model generation, digital surface model production and orthophoto creation. Additionally, the paper discusses the integration of UAV photogrammetry with other technologies, like LiDAR sensors as well as remote sensing imagery, outlines existing applications of machine learning for the further processing of photogrammetric products and discusses the combined use of the photogrammetric results with GIS (Geographic Information Systems) and BIM (Building Information Modelling). Finally, the paper presents several case studies across cultural heritage sites in Greece, where UAV-based 3D modelling has been applied, demonstrating the potential of UAV photogrammetry and multi-image reconstruction procedures in efficient and accurate cultural heritage documentation of sites of varying characteristics with complex geometry.