Multisensory VR experiences based on auralization and HBIM. The Teatro del Maggio in Florence

The paper intends to present a series of experimental HBIM applications conducted as a follow-up on some of the results obtained within the European project "AURA - Auralisation of Acoustic Heritage Sites Using Augmented and Virtual Reality" co-funded since 2021 by the Creative Europe Programme and concluded at the end of 2022. This project was aimed at exploring new horizons of use of the Acoustic Heritage of sites related to the Cultural and Creative Industries (CCI), such as theaters and concert halls, by investigating the potential of auralization - a technique of simulating the acoustics of a real environment within 3D models - and combining it with visual representations of the virtual environment based on accurate digital surveys. In order to achieve this goal, three emblematic European case studies were thus examined: the Konzerthaus in Berlin (DE), the Opera House in Lviv (UA) and the Teatro del Maggio in Florence (IT). Within this paper, a solution based on Nurbs-to-BIM modeling and data-enrichment techniques in an HBIM environment is tested for the Florentine case study, with the aim of obtaining informative 3D assets on which to develop VR systems capable of virtually simulating not only the visual aspects of the model, but also the acoustic behavior of the environment. The acoustics theme is indeed an increasingly debated topic in the field of documentation and virtual fruition of Cultural Heritage. Besides AURA, in fact, a number of research projects focusing on the acoustic and virtual reconstruction of architectures, such as the Greek theater of Tindari or Notre Dame Cathedral in Paris, have been carried out over the past few years. As for these, within AURA, a methodology including first a digital survey using TLS, was planned. The data obtained then became the basis on which to develop, through Nurbs modeling, the architectural and furniture elements. For each of these, semantically and materially subdivided, specific acoustic parameters were then identified, and by which, an acoustic database was developed to support subsequent auralization processes. The present research aims to take a further step forward in the field of HBIM, starting from the results obtained for the Teatro del Maggio, and proposing a methodology based on the virtualization of the case study through Nurbs-to-BIM-to-VR processes. This first involved the implementation of morphologically reliable assets into the HBIM environment, but also - and more importantly - their informatization both materially and acoustically. For the development of the subsequent auralization and virtualization processes, the Unreal Engine platform was used, which allows via plugins perfect interoperability with the information metadata of the BIM models, as well as excellent potential from the point of view of ArchViz and VR. Within this research, therefore, an investigation was made to translate the experience of listening to and experiencing theatrical environments into virtual perspectives, proposing a replicable methodology that exploits the HBIM information potentials for the development of acoustic simulation processes and multisensory VR experiences, in order to identify new opportunities for communication and documentation of the Acoustic and Architectural Heritage.