Computer vision-based orthophoto mapping of complex archaeological sites: the ancient quarry of Pitaranha (Portugal-Spain)

Abstract

Ancient quarries are intriguing archaeological sites, but their detailed recording is complex. This paper presents a cost-effective approach to mapping of the Roman quarry site of Pitaranha (Portugal–Spain). First, aerial photographs were acquired using a radio-controlled digital reflex camera attached to a Helikite, which allowed the acquisition of the necessary low-altitude aerial footage in the very unstable wind conditions above the quarry. Using computer vision algorithms, the resulting set of photographs was semi-automatically transformed into a Digital Surface Model (DSM) and a corresponding orthophotograph. Besides focusing on the acquisition and processing method, this paper evaluates the accuracy of the generated products. The orthophotograph proved to be satisfactorily accurate for 1:200 hard-copy mapping