TECNOLOGIE DI RILIEVO 3D PER LA DOCUMENTAZIONE, L’INTERPRETAZIONE E LA VALORIZZAZIONE DEL PATRIMONIO ARCHEOLOGICO: IL CASO STUDIO DEL PARCO ARCHEOLOGICO DI LILIBEO-MARSALA

In recent decades, the application of geomatics technologies and methodologies to archaeological studies has led to a substantial change in onsite survey techniques and allowed an interdisciplinary approach between archaeology and digital technologies. The employment of these techniques aims to reduce the time of research and documentation, to acquire large amounts of data and to manage, in a more efficiently and quickly way, different datasets. Moreover, these new approaches provide non-invasive, flexible, low-cost methodologies to improve archaeological documentation from a quantitative and qualitative point of view. Nowadays, archaeologists can take advantage of various recording techniques to produce highly accurate 3D models and ortho-images of archaeological sites. Far from replacing the more traditional techniques, the development of new geomatics ones tries to efficiently and effectively catch needs of the archaeological research. The main geomatic technologies used in the archaeological field for three-dimensional (3D) surveys are related both to range-based techniques (accounting for the use of active sensors, such as terrestrial laser scanner) and to those using image-based approaches (using passive sensors - mainly photographic cameras - and photographic images). The use of a terrestrial laser scanner for archaeological aims is becoming a common strategy to directly capture the 3D geometric information of an object. This method is based on costly sensors, but it provides a highly detailed and accurate description of complex surfaces. Image-based approaches, including photogrammetry, exploit 2D image measurements to recover 3D object information. Photogrammetric data produces highly detailed photographic textures to generate photorealistic 3D models. Moreover, in recent years, the development of Unmanned Aerial Vehicles (UAVs) has become more popular in archaeological excavations. UAV systems become a useful, versatile and cost-effective approach to record, measure and fully document large archaeological areas. They represent the fastest way to produce high-resolution 3D models of entire sites and allow archaeologists to collect accurate spatial data. The integrated use of range- and image-based techniques ensures the possibility to entirely record articulated structures by improving archaeological analysis and to support the generation of spatial and visual records of archaeological sites for conservative purposes. The work is part of the international research project “The Archaeological Map of Lilybaeum”, conducted by the Archaeological Institutes of the Universities of Palermo and Hamburg, the Soprintendenza of Trapani and the Archaeological Park of Lilibeo-Marsala. The area of Capo Boeo, which represents the focal point of the Archaeological Park, extends for about 28 hectares inside the modern city of Marsala. This wide area, spared by building expansion, preserves a considerable portion of Lilybaeum, the city founded in the IV century B. C. by the Punic. The city occupied the westernmost promontory of Sicily, in a strategic position that was its strong point since its foundation. On all four sides, the city was surrounded by imposing walls; it was also protected by the sea on two sides and by a moat towards the inland. The study presents the outcomes of several 3D surveys of the archaeological remains of Lilybaeum. Since 2017, UAV, laser scanner and terrestrial photogrammetric acquisitions have been planned and carried out to complete the previous traditional documentation of the Capo Boeo area. The research activity had a twofold aim: the application and evaluation of geomatic techniques for archaeological documentation, with particular focus to the integration of close-range aerial photogrammetric surveys using SAPR and laser scanner surveys, and the construction of a 2D and 3D georeferenced database to derive new information (such as updated plans) for developing the Archaeological Map of Lilybaeum