Standard for geometric and informative reliabilities in HBIM models

The modelling of a historic building constitutes a restitution of the architectural object, result of a critical reading made by the researcher. For a valid scientific representation of the architectural heritage, issues relating to the “transparency” of information sources and the “reliability” of modelling become fundamental. Through the development of same case studies, the paper proposes and tests a procedure by which it is possible to transparently declare the sources that have substantiated the modelling and, at the same time, evaluate and communicate the reliability of the digital reconstruction. Aim of the paper is the definition of a standard for the evaluation of the reliabilities which is dependent from the LoD of the objects. Taking into consideration the dual meaning of 3D representation and heterogeneous information system of BIM models and the peculiarities of built heritage (importance of the declaration of sources; availability of information that is often not exhaustive and non-uniform for all elements; modelling based on the critical interpretation of data, etc.), the developed standard was divided into different types of reliability and sub-reliability, depending on LoD and, in the case of non-geometric information, on the type of source. The obtained result is a standard that can make the HBIM an effective procedure to be used for the survey and for the evaluation of the restoration project.