A BIM-Based Model for Heritage Conservation and Structural Diagnostics: The City Walls of Pisa

The use of Historical Building Information Modeling (HBIM) is gaining much interest in the architectural heritage domain due to its ability to support the design and management of conservation activities. Any maintenance, preservation or revitalization strategy requires obtaining a complete knowledge of the site and conducting critical investigations on geometrical, physical, and documental data. The benefits of implementing HBIM comprise the possibility to integrate the data coming from multiple sources, inspections and diagnosis techniques, as well as to employ standardized and robust tools for orienting cultural heritage asset management. This study explores the challenges of developing HBIM on ancient city walls, whose great dimension and extension require adapting the conventional workflow in order to obtain results in a reasonable time. The combination of traditional geometric surveys and more innovative techniques allows for a complete and extensive photogrammetric documentation of the city walls. The acquisition process has been speeded up without compromising the accuracy of the resulting model, thus offering a reliable representation of multiple issues of the historical assets, ranging from its features and state of conservation to its structural deficiencies. By applying the novel workflow to the city walls of Pisa, the paper discusses the interoperability among different tools and the broad versatility of the proposal for large architectural heritage.