Reconstruction of S. Margherita Project of 1685 as designed by Agostino Barelli

This paper presents a structured three-dimensional (3D) reconstruction methodology of architectural heritage adopted and implemented in the context of the CoVHer (Computer-based Visualisation of architectural Heritage) Erasmus+ project. The methodology consists of a multi-step process for hypothetically reconstructing never-built or demolished architectural heritage from the past in the form of 3D digital models. This reconstruction methodology was tested over the years with professionals, scholars and laypersons, on several case studies in the context of international workshops, museum exhibitions, VR dissemination, and it was also tested with students at the architectural drawing course at the University of Bologna. This last experimentation was particularly important because fostered us to systematise its steps and make it more easily sharable and applicable while not compromising quality and robustness. The methodological steps that we are going to address and discuss in this paper are: a) data acquisition, b) critical evaluation of historical and architectural sources, c) 2D digital redrawing of graphic material, d) construction of the 3D model, e) visualisation, f) uncertainty assessment and communication, g) documentation, and h) publication with a particular focus on interoperability and accessibility. These steps are explained in detail in order to be applicable to similar case studies and foster reproducibility, comparability, accessibility, transparency, and interoperability of the digital reconstruction. These are the key principles already recommended by the FAIR principles (Findable, Accessible, Interoperable, Reusable), the Seville Principles, and the London Charter, among others. The methodology, despite being tested on various case studies and fields, has been proven to be particularly effective for never-built or demolished architectural heritage with known authors. This paper presents the case study of the reconstruction of the unbuilt Church of S. Margherita in Bologna, designed by Agostino Barelli in 1685. This exemplary case study covers all aspects of our reconstruction methodology.