Recording the marble blocks of the Milan cathedral: Synergy between advanced survey techniques

The constant and continuous maintenance activities of the Veneranda Fabbrica guarantee the conservation and the use of the Duomo of Milan. This complex conservation site daily deals with the problems related to the ordinary and extraordinary interventions, combining simultaneously many different technical skills and ensuring at the same time the accessibility of the Monument. In the case of Duomo, the protagonist of the conservation activities is the 'marble block.' The yard organises the activities by identifying the areas that need intervention and recognising the marble ashlar that will be affected by substitution, tessellation and consolidation operations. The target of the integrated survey methods (photogrammetry and laser scanner) and the subsequent modelling phase is to return a model where the marble ashlar is recognisable in its shape, size, position and texture. For this reason, the 3D models, two-dimensional representations, and orthophotos produced in these last years aim to correctly identify the constituent elements and provide technical support for the operations carried out on the site. Simultaneously with the survey and the modelling activities, an ad hoc online system has been created for the consultation and sharing via a web of processed data by both Veneranda technical office and the yard of the monument. This article presents the ongoing activities (integrated 3D and multi-scale survey, 3D modelling and web data management) and the expectations in the next future.