Photogrammetry and 3D reconstruction in Archaeological Excavation on Elephant Terrace, Siem Reap, Cambodia

Abstract. This study presents the photogrammetric documentation and archaeological investigation of a 14-meter section of the Elephant Terrace in Angkor Thom, Siem Reap, Cambodia. While earlier restoration efforts by the École française d’Extrême-Orient (EFEO) focused on surface-level repairs, this project involved the full dismantling and excavation of the northern terrace segment to examine its internal structure and construction sequence. A total of 705 terrestrial and aerial images were processed using Agisoft Metashape Professional v2.0.2 to generate a high-resolution 3D model. Accuracy was evaluated using Ground Control Points (GCPs) and Check Points (CPs), yielding an RMSE of 3.21 cm and an average reprojection error of 0.438 pixels—both within acceptable thresholds for archaeological documentation. The resulting model enabled a detailed reconstruction of five major construction phases, revealing the use of compacted earth, laterite walls, and sandstone facings. Notably, the photogrammetric data were acquired during excavation, eliminating the need for a dedicated imaging campaign. This demonstrates the method’s practicality for integrated field documentation. The study confirms photogrammetry’s value in archaeological research, offering accurate visualization, efficient data capture, and improved interpretive potential for heritage structures.