SfM Photogrammetric Techniques Applied in the Building Archaeology Works of the Old Cloister of the Monastery of San Francisco from the 16th Century (Cazalla de la Sierra, Seville)

Abstract

The cloister from the old monastery of San Francisco (Cazalla de la Sierra, Seville) has been suffering a series of remodeling transformations from its original construction in the 16th century to the current day. Thus, a study of building archaeology needed to be accomplished by using photogrammetric techniques by SfM (Structure from Motion) and laser scanning or TLS (Terrestrial Laser Scanning), which ensure the geometric exactitude and high resolution of the facings surveying. For that, over 500 images were taken for the 4 existing facings (about 78 lineal meters) from which a photogrammetric model was obtained of over 50 million polygons, as well as a cloud of over 40 million points from the laser scanning. It can be concluded that by using the techniques of SfM, the task of documenting, analyzing and studying the facings of the historical building in order to establish its evolutional process gains not only precision and exactitude but also opens the possibility to go further by obtaining products that are capable of helping us conserve, restore and protect the historical heritage, as well as generate the 3D virtualizations planned for the diffusion.

Diagnostic Process of an Ancient Colonnade Using 3D High-Resolution Models with Non-Invasive Multi Techniques

“…The CRP technique based on SfM is a proximal sensing NDT methodology used for the estimation of high-resolution 3D models from different sequences of overlapping 2D images of a studied object. SfM photogrammetry is commonly used to define the entire reconstruction workflow of artifacts, starting from sets of good quality images to generate a dense point cloud [ 8 , 11 , 41 ].…”

“…This digital documentation provides the basis for the management and maintenance of monumental structures over time and provides information that is suitable for reaching different targets, as well as providing useful data for the different branches of applied research [ 4 , 5 , 6 ]. In particular, CRP and TLS are very useful for the analysis of shallow parts of stone building materials, as they allow the inspection of large surfaces without any contact or damage [ 7 , 8 , 9 , 10 , 11 ]. However, during a diagnostic process on the conservation state of stone building materials, even when these technologies are applied in synergy, they need to be complemented by the parallel application of other diagnostic techniques, such as ultrasonic techniques that inspect the materials inside based on an analysis of the propagation of the ultrasonic signals [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”