Surveying and modelling the Main Spire of milan Cathedral using multiple data sources.

This paper presents a possible way of surveying and modelling very complex architecture, integrating different instrumentation and modelling methods. In particular, it aims to draw attention to a possible measurement and data processing procedure allowing the rapid collection and post-processing of data in order to extract classical architectural products such as sections and profiles, and to build complete, accurate 3D models. The need is to structure a multiple data source procedure within a five-year project (still in progress) to survey and model the main spire of Milan Cathedral three-dimensionally. The spire is a very complex object and, for this reason, provides a really useful, challenging field test for new 3D survey technologies and, in particular, for integrating a variety of modelling methodologies. The paper describes survey workflow and processing steps, focusing on problems and justifying key choices.