Innovative Approaches through 3D Survey and Virtual Technologies for the Geometric and Semantic Fruition of Built Heritage Sites on the Web

Nowadays recent advances in Geomatics and Computer Science led specialists to explore new methodologies for the preservation and valorization of Built Heritage (BH). In fact, if on one hand the preservation of monumental complexes needs to remotely manage virtual representations of the real environments to be preserved, on the other hand the valorization allows visitors to virtually explore BH sites in remote, thanks to the spread of web technologies. The main challenges about the virtual fruition of BH sites are related to the management of 3D big data digitized geometries and the requirement for property software-based solutions. This work explores a possible strategy, based on open-source technologies for the web fruition of 3D geometric and semantic information of BH sites from 3D digitization. The first results of this research are related to the cloister of the Cathedral of Cefalù (Italy), which represents a classic example of a BH site that, for its extraordinary importance and its state of preservation, could benefit from the application of virtual technologies for conservation and fruition purposes. The work describes the acquisition of the 3D geometric dataset through laser scanner and photogrammetric surveys, its optimisation, and the design of a web-based platform for the fruition online of 3D geometric and semantic information. The web navigation system was developed through Three.js JavaScript WebGL libraries, inside a HTML5 compliant environment, connected in real-time to Postgres Relational Database Management System through the activation of a Python module in an Anaconda platform. In this way, the geometric information, hosted by the WebGL environment, was connected in real-time to the semantic information stored in the database. This system represents a prototypical structure for the future development of a full platform for the web exploration and management of BH sites developed with low-cost technologies and useful for a large variety of stakeholders (from municipalities to private companies) who manage BH sites.