3d Survey Technologies for Reconstruction, Analysis and Diagnosis in the Conservation Process of Cultural Heritage

The recent survey technologies, play a leading role in the process of knowledge of the cultural heritage. In fact they are finalized to the acquisition of geometric data necessary to describe usefully geometric features and peculiarities of historical monuments necessary for their conservation and safeguard. Besides digitalisation of the acquired data, allows the same data availability by different typologies of users in order to spread and share knowledge for cultural heritage valorisation. Quick stereo-photogrammetric systems and laser scanner technology have advantages but also limits referring to the elaboration, management and possibilities of use. The recent development of digital stereo-photogrammetric systems allows the definition of 3d visualization and navigation environments within which the data referring to geometric consistency is combined, without loss of rigour, with other qualitative, morphological and colour information specific to the photographic document. The laser scanner technology likewise permits a detailed three-dimensional description of the artefacts geometry, without subjective interpretation from the operators. Therefore laser scanner opens up extremely interesting horizons to possible geometry analyses or to evaluations of monuments state of conservation and static conditions. The necessity to compare these different survey technologies becomes fundamental to verify the accuracy of acquired numeric data, to evaluate their possible integration and to define different protocols of use in relation to the artefacts morphological-architectural characteristics and to the survey finalities. The critical aspects of the described topic will be proposed through the analysis of a specific study case: the documentation of the roman triumphal arch of Augustus in Aosta.