Survey method for earthquake damages in the "Camera degli sposi" of Mantegna (Mantova)

Cultural Heritage constitutes a fundamental resource for all Countries, even in economic terms, as it can be considered an extraordinary tourist attraction. This is particularly true for Italy, which is one of the Countries with the richest artistic heritage in the world. For this reason, restoration becomes an essential step towards the conservation and therefore valorisation of architecture. In this context, this paper focuses on one of the first stages that allow us to reach a complete knowledge of a building. Because of the earthquake of May 2012, the Castle of San Giorgio in Mantova (Italy) presented a series of structural damages. On the occasion of its upcoming re-opening to the public, the Soprintendenza per i Beni Architettonici e Paesaggistici per le province di Brescia, Cremona e Mantova has requested an analysis and evaluation of the damages for the development of an intervention project. In particular, a special attention was given to the “Camera degli Sposi” ("Bridal Chamber"), also known as the Camera picta ("painted chamber"). It is a frescoed room, with illusionistic paintings by Andrea Mantegna, located in the northeast tower of the Castle. It was painted between 1465 and 1474 and commissioned by Ludovico Gonzaga, and it is well-known for the use of trompe l'oeil details and for the decoration of its ceiling. The seismic shakes damaged the wall decorated with the “Scena della Corte” (“Court Scene”), above the chimney, re-opening an old crack that had to be analysed, in order to understand whether the damage was structural or just superficial. The diagnostic analyses constitute a fundamental prerequisite for the elaboration of any kind of intervention or restoration in any architectural, artistic or archaeological framework. To obtain a description of the conservation state of the Camera, non-invasive integrated survey techniques were applied. The purpose of the study presented here is the definition of a methodology able to support the necessity of a rapid restoration. In order to acquire the useful data for the damage evaluation, we used three different kinds of laser scanners. These were chosen according to the dimension of the object that had to be surveyed. The first is Riegl LMS-Z390i, a time of flight laser scanner that was used to survey the external surface of one of the fronts of the Castle. The second one is Faro Focus 3D, a phase-based scanner, used for the indoor survey of the “Camera degli Sposi” and the touristic path from the “Scalone di Enea” to the Camera itself. Finally, a triangulation laser scanner, Konika Minolta Vivid VI-9i, was used to measure the dimension of the crack, for its whole length. All the data acquired by these scanners were georeferenced in the same reference system, defined through a topographic network. The data collected were processed in order to obtain a number of representations, both in two and three dimensions, useful for a complete knowledge of the state of condition of the building. This paper analyses the surveying process in all its different phases: from the planning, to the data collection, and the postelaborations