Archaeological crop marks detection through drone multispectral remote sensing and vegetation indices: a new approach tested on the Italian pre-Roman city of Veii

The use of drones for the archeological research have grown rapidly in recent years, as the increasing number of studies mentioning their use attests. Still, a few of these studies focus on the identification of archaeological marks, and even fewer are based on multispectral imaging. The study shows how drone multispectral remote sensing together with an agronomic approach, can guarantee great advantages in the identification of crop marks, bringing opportunities both from an economic and scientific point of view. An innovative multispectral camera allowed the recording of the vegetation reflectance in 4 different bands of the electromagnetic spectrum, included the near infrared, the most important band for vegetation analysis. Aerial imagery was processed through the use of vegetation indices to identify crop marks, trough the analysis of the type and variations of vegetation stress produced by buried remains. The experimental application of this technique on a portion of the Etruscan city of Veii showed how, even in a single flight performed slightly late compared to the ideal timing, it was possible to detect and interpret a considerable amount of particularly significant archaeological marks.