Detecting Change in High Temporal Resolution UAV Photogrammetry at Active Archaeological Excavations: International Field School Excavations at NI Stobi 2018
Photogrammetry is a common technique used in the documentation of archaeological excavations; it has been integrated into several sites since the early 20th century. Photogrammetry allows researchers to analyze and document important finds and structures. The cost of photogrammetry today has declined significantly since the early 20th century making it possible to perform daily RPAS photogrammetry over an active archaeological site. Most researchers today use photogrammetry to create orthophotos that can be traced with 2D line work, but the 3D data is essentially thrown out. This 3D data can provide valuable information using change detection. Photogrammetric change detection analysis is common when it comes to the protection of cultural heritage sites but is not commonly used on active archaeological sites. Using 3D data, we can compare Digital Terrain Models (DTMs) and Point Clouds, resulting in defined locus boundaries that can enhance the archaeological documentation. This study utilizes RPAS (Remotely Piloted Aerial Systems) data gathered during an international field school at Stobi, an archaeological site in the Republic of North Macedonia, in 2018. Using two different programs, 3DM Analyst and CloudCompare, this project shows the subtle changes that occur on an active archaeological excavation. These programs have special features that allow the user to compare the data to calculate and visualize these differences. Information gathered from field journals and locus sheets assists in the analysis of the changes that occur within the locus boundaries. The 3D information gathered can provide important information in understanding how the excavation is proceeding and what the next steps are.