Sperimentazione di LiDAR a stato solido per comparti urbani fortificati. Il caso studio dei vicoli saraceni di Forio d’Ischia

Since ancient times, the island of Ischia, the largest of the Phlegrean Islands to the west of the Gulf of Naples, has been considered a land of great interest both for its strategic position in the Mediterranean Sea and for its rich landscapes and architecture. Among these distinctive features of the island, it is worth mentioning the unique urban layout of the Saracen alleys that developed around the watchtowers, which still characterize the village of Forio d’Ischia today. This defensive need, common to many Mediterranean locations, has led to distinctive urban and architectural outcomes only in Forio and a few other places.To explore this peculiarity, the research has unfolded in subsequent phases, starting with historical and cartographic analysis and gradually enriched by the digitization of the urban area developed around the Saracen alleys. The acquisition of digital data - both metric and colorimetric - has been primarily intended as a priority action for analyzing the defensive labyrinth in relation to the urban fabric and its architectural expressions. To this end, the digitization was carried out by integrating range-based and image-based techniques. Specifically, a state-of-the-art LiDAR with hybrid solid-state sensors was used to dynamically acquire the metric and dimensional information of the urban area bordered by Via Nuova Marina, Via Lustro, Corso Regine, Vicolo Torrione, and Vicolo Sant’Antonio Abate. To increase the point cloud density, a TLS was employed in key locations, such as around the most significant defensive structures (e.g., Torre “il Torrione”, Torre Quattrocchi, etc.).Finally, to refine the color and surface texture data, both aerial and terrestrial photogrammetric survey campaigns were integrated. The collected data, in addition to representing an important update to the documentation, enabled the extraction of new information useful for both architectural design and the enhancement of the site – custodian of legends and defensive techniques typical of the Ischian tradition.