Accuracy assessment of different remote sensing technologies over the cultural heritage site of Helike, Achaea, Greece

Diverse archaeological activities such as archaeological site documentation, excavation planning, or cultural heritage management can benefit from 3D metric data produced by Unmanned Aerial Vehicles or Terrestrial Laser scanners. A common characteristic of both technologies is their ability to generate particularly dense point clouds of high accuracy and fidelity. Although both methods produce millions of XYZ points, the way the data is collected is very distinct resulting in point clouds with severe differences. In the current study, orthophotos and Digital Surface Models from three different commercial UAVs are compared. Specifically, two tetracopters (DJI P4 and DJI P4 Pro and a hexacopter (Matrice 600) were used to map a large complex building of the Late Classical-Hellenistic settlement of Helike, including the excellently preserved installations of a large scale dyeing/fulling textile workshop, excavated by the Helike Project in recent years. At the same time, a Terrestrial Laser Scanner (BLK 360) was also used to collect 3D point clouds on the ground level. Hundreds of ground control points collected with RTK GNSS sensor were used to validate the accuracy of the derived point clouds. The validation procedure was performed in ArcMap by comparing 3D representations with the collected GNSS measurements.