Comparison between topographic and photogrammetric techniques fordeformation monitoring of the dome of the Massimo Theatre in Palermo

This paper shows the first results of a study aimed at monitoring the deformations of the dome of the Massimo Theatre in Palermo caused by thermal dilatations, with the use of topographic and photogrammetric integrated techniques. Particularly, two robotic total stations and high precision digital photogrammetric systems were employed. In order to correlate thedisplacements of the rollers on which the steel structure of the dome rest with the thermal gradients, different thermal images were acquired by a thermal imaging camera. The main goal of the work was to compare the two techniques with reference to very small(submillimeter) deformation measurements. The obtained results show that the rollers are still working correctly. In fact, for a thermal gradient of 6 °C both topographic andphotogrammetric techniques determined displacements in the order of 0.8 mm, according with the expected deformations of the theoretical model.