A Shadow of Its Former Self: Exploring the Urban Landscape of Iron Age Hillforts Through an Integrated Analysis of Drone LiDAR and Geophysics

Abstract

LiDAR data are quite commonly used for the analysis of archaeological landscapes over large areas in order to identify a wide range of cultural features. Open access datasets provided by regional or national services are very suitable for this medium/large scale exploration, but they often fail in the identification of more subtle microtopographical features at a site scale. Airborne Laser Scanning (ALS) with higher resolution LiDAR coverage can fill this gap, offering valuable clues about the internal spatial organization of ancient settlements. In this paper, we offer a representative example of this casuistry focused on Iron Age fortified sites (hillforts) in the Southwest of the Iberian Peninsula. The process of capture and processing of LiDAR data combined with results of photogrammetric flights is explained. An analysis based on the application of visualization methods designed for archaeological investigation was made, in order to extract as much information as possible. From this point onwards, automatic and semiautomatic detection techniques were developed in order to recognize regular patterns that could eventually help in the reconstruction of the urban landscape of the sites. Finally, the results are combined with other nondestructive methods in order to provide a reliable diagnostic about the cultural interpretation of the features we have detected.