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)

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.