High resolution terrestrial thermography of archaeological sites

AbstractThermal infrared imaging, or thermography, is the remote sensing technique of detecting variations in ground temperature caused by exposed or subsurface archaeological remains either absorbing or radiating heat. Despite its conception in the 1970s, the practice has to date been rarely utilized, as a result of the high cost of the technology and the complex interplay of environmental variables. However, recent studies have demonstrated the effectiveness of the technique, especially when combining modern thermal cameras with unmanned aerial vehicles (UAV). Yet these papers often focus on mid‐ to high‐altitude flights, where the technique is only effective at detecting larger thermal anomalies. This article presents a new method for terrestrial thermography, developed for the Zagora Infrared Photogrammetry Project (The University of Sydney and the Australian Archaeological Institute at Athens). The project undertook a six week thermal investigation of the Early Iron Age site of Zagora and the surrounding hinterland utilizing the newest commercial thermal cameras and UAVs. The method of terrestrial thermography involves using photographic poles and photogrammetry to create high‐resolution thermal orthophotographs, which allow the detection of smaller thermal anomalies, providing significantly more detail than aerial thermography. Several features were discovered using this method, including a possible kiln, which would be the first ever identified at the site.