Methods and tools for generating the DTM of an archaeological site: the case-study of the photogrammetric survey of Nora (Sardinia, Italy)

This paper describes the high-resolution survey of the archaeological site of Nora (Sardinia, Italy) using the aerophotogrammetric technique. The survey was conducted in October 2021 on a 14-hectare peninsula located in the Gulf of Cagliari. Previous attempts to survey the area, aside from the 1 metre/pixel LiDAR survey carried out by the Region of Sardinia, have been hampered by the challenges posed by the size of the area and the costs involved. The Digital Terrain Model was obtained from the 3D model created with the Agisoft Metashape© software by removing the buildings and the vegetation. The segmentation process was carried out using Cloud Compare and the resulting DTM was then analysed using the geomorphological analysis tools provided by QGIS. The seabed DTM was obtained through several survey campaigns between 2013 and 2015, using the same software. The terrestrial DTM was merged with the seabed DTM, resulting in a comprehensive 3D and 2D model of the peninsula and its surroundings. The final DTM was printed with rapid prototyping technologies to explore its potential use as a tactile model for promotion and dissemination in the field.