Survey and Photogrammetric Restitution of Monumental Complexes: Issues and Solutions—The Case of the Manfredonic Castle of Mussomeli

The latest results obtained through photogrammetric restitution enhanced by GNSS (Global Navigation Satellite System) RTK (Real-Time Kinematic) survey achieved increased levels of accuracy. These survey solutions are used to rapidly obtain a detailed model with an excellent level of accuracy (centimetric) with cheaper equipment. However, the contour conditions are not always favorable for obtaining the best results in a simple way. The work presented in this paper shows the survey and the photogrammetric restitution of the Manfredonic Castle of Mussomeli in Sicily, developed as a part of the PON NEPTIS European Project, aimed at the valorization of Cultural Heritage (CH). This case is a typical example of a complex survey carried out in an impervious environment where traditional survey procedures are totally useless or require a longer amount of time and great effort if a high level of accuracy is requested. In this case, considering the natural conditions of the site, the only way to perform the task has been the use of photogrammetric restitution based on UAV (unmanned aerial vehicle) technologies and GNSS survey. The precision obtained from the results allowed us to create a geometric 3D reconstruction of the monumental complex of the castle for the valorization of the site, which was the main goal of the whole process. The procedure that is the focus of this work is a test of rapid 3D CH survey and documentation in an impervious environment