The work is the result of a long research process that led to the realization of a BIM system starting from photogrammetric survey. Subject of the investigation is the main spire of Milan Cathedral. In particular, the work has evolved over four years following step by step the evolution of 3D survey and modeling methodologies with particular attention to the “image based approaches”.
This has enabled to produce a complete model of the spire and to create a prototype of BIM useful to manage the huge 3D data together with images and information to be used during the restoration works.
Today (2014) the whole object ‘Spire’ is represented by a detailed and rich 3D model that represent all marble constructive blocks, ornaments and decorations and also structural elements.
The last research activity was aimed to create a WEB platform in order to visualize the model online and use it as base to collect information. The main aim was to converting the 3D model from a static representation to a dynamic information tool capable to collect multi-disciplinary external data and to document changes over time.
The main Spire was surveyed using a multi-scale and multi-data approach, searching for the most appropriate method. Given the complex shape and the size of the spire, it was impossible to proceed in a ‘conventional’ way. In addition to that, the morphology of the object and its environment play an important role in defining the acquisition strategy.
The final obtained model fully satisfies the accuracy requirements. It represents the main spire in all its complexity the main structure of pillars and arcs, the complete decorative apparatus, the structural details as chains, internal and external armors and additional functional elements. All that parts are divided in the single constructive units: the marble blocks making it easier to understand the complexity of construction of the structure.