3D laser scanning surveys in the modelling of cultural heritage.

3D high resolution survey is now performed mainly with photogrammetry and laser scanning methodologies providing very dense and accurate point clouds. Alignment of all acquired points in a defined reference system generates a metrically correct 3D model of the objects. Photographic information can be associated to the model too. Terrestrial applications have recently demonstrated the potentialities of the techniques, which are useful in different fields. In this chapter 3D survey methodologies are explained, discussed and applied. These techniques have been used in different domains: in engineering field, as a geometrical support to structural analysis and in the monitoring of small variations by comparison of different surveys, co-registered in the same reference system. In architectural field, photogrammetry and laser scanning techniques are widely used for documentation and as support for restoration of buildings, while in territory survey are used for cartographic map production and in the monitoring of deformation areas (volcanoes, glaciers and landslides areas, shorelines) comparing the surveys at different time. In archaeology and in the study of cultural heritage, they allow for virtual reconstruction of buildings and objects. Moreover, in medicine, a metric survey helps quantitative evaluation of prosthesis and pre- and post- surgical interventions conditions by comparison of different models. In the sequel, some applications are described, showing different aspects concerning the 3D survey in the framework of cultural heritage. The “Cavallo ligneo” of the “Palazzo della Ragione” in Padua (a wooden horse from a middle age economical and political building), allows focusing on reconstruction of lacunas in the data generated by operative limitations. The “Arche Scaligere” in Verona, is used for discussing the integration between laser scanning and digital photogrammetric data, thus evaluating the accuracy of the methodologies. The work on the “San Prosdocimo” Chapel, which is located in “Santa Giustina” Basilica in Padua, is focused on different procedures for texture mapping of digital images on the 3D models distinguishing between point cloud models and surface models