Integration of image and range-based techniques for surveying complex architectures

Abstract. In the last decade the Cultural Heritage field has deeply benefited from the opportunities of collecting accurate and detailed 3D information of sites and artifacts using both image- and range-based techniques. Since few years ago these technologies were not so extensively used, mainly because they were very expensive, required expertise and the pipeline and procedures related to their use were not straightforward, nor consolidated. But in the last years significant improvements in the digital survey technologies have been reached, with the principal scope of simplifying reality-based survey procedure and providing a series of different solutions that combine the automation of processes with accuracy and resolution performances. In addition to these aspects, the lowering of costs and the consequent widespread use of some survey solutions, such as, for example, range-based, as well as terrestrial and UAV image-based ones, have recently given strong impulse to the widening of use of these technologies in the Cultural Heritage field. As a consequence, this range of possibilities shows that in this field, where case studies have peculiar geometric and radiometric characteristics and survey conditions are often unique, preliminary investigations and evaluations are mandatory in order to define the most suitable solution to adopt. In this context, this paper presents preliminary results from the Santa Maria di Pomposa survey project, with the purpose of starting a deep investigation on the integration of 3D digital technologies and how they can provide complete and multi-scalar information about complex architectures. This purpose is particularly important in case studies where analysis have to be conducted at different scales of complexity. Structural analysis are just an example of the need to easily handle complete and global information that have to be deeply and detailed analyzed, eventually showing the behavior of structures over time. Within the adopted methodology, the comparison of results obtained using different approaches represents an indispensable step in order to evaluate and select the most reliable and suitable solutions to adopt within the final integrations process.