Health monitoring of complex structure using TLS and Photogrammetry

The demand for high-definition surveys within cultural heritage projects represents one of the main factors which promoted the use of laser scanning technology and photogrammetry. By measuring millions of points within relatively short time periods, terrestrial laser scanners allow to derive complete and detailed 3D models of real objects from acquired point clouds. Despite the wide spread of Terrestrial Laser Scanning (TLS) technology, the use of such systems for stability control is still a research field not much investigated. In the view of in-depth investigation on this topic, a three-years project has been established in order to evaluate the use of multiple surveying techniques for the stability control of a complex historical structure. To this aim, terrestrial laser scanning, total station (TS) and photogrammetry are being employed to survey the historical building Olympic Theatre, in Vicenza. Known as the oldest surviving enclosed theater in the world, this structure was constructed in 1580-1585 by Andrea Palladio, one of the greatest architect of the Italian Renaissance. The main goal of this work is to analyse and verify the stability over the time of this kind of structure by applying the Finite Element Methos (FEM) analysis to a highly detailed 3D model of the Theater. A few surveys of the Theater have been carried out with consumer digital-reflex camera Nikon D200, Leica Laser Scanner HDS 3000 and Leica Total Station TCR 705 in order to derive a complete 3D model. This paper presents the results obtained from these surveys and highlights issues and difficulties related to the application of laser scanning and photogrammetry to an unusual and complex geometry such as the Olympic Theater in Vicenza.