3D LASER SCANNING SURVEY FOR CULTURAL HERITAGE. A FLEXIBLE METHODOLOGY TO OPTIMIZE DATA COLLECTION

Abstract. The paper describes an operational working methodology to be applied for surveys with phase-shift laser scanning, which allows defining a guidelines system to optimize in-field data collection. While reducing the number of scan positions still using the same quality, it is possible to obtain smaller files, in order to limit the computational requirements during editing and post-production. Nonetheless, this methodology guarantees results that are qualitatively comparable to the standard data collection process. Consequently, the angle ranges have been analyzed to find a value that guarantees for the survey a point cloud lighter and more manageable and, at the same time, that maintains a reasonable accuracy. Subsequently, two parameters were defined, “redundancy” and “closeness”, to find an operational process that allows to schematize what is usually achieved with the help of experience in the field: to evaluate the minimum number of scan points that can ensure the necessary overlap for optimal coverage of the entire building surveyed. After defining the study of the ideal situation, the model is applied in a case study, situated in a densely built context, typical of European historical urban centers: the main façade of the G. Ciamician Institute of Chemistry of the University of Bologna (Italy).