The "Pieve di Santa Maria" in Arezzo (Italy). From the laser scanner survey to the knowledge of the architectural structure.

The parish church of “Santa Maria” is considered one of the most important medieval buildings of Arezzo Although the church is attested from 11th century, it is between the 13th and 14th centuries that reached its current consistency, characterized by the particular façade with small columns on several levels and an imposing bell tower. Later, from the 16th to the 18th century, the church underwent profound transformations, that were almost completely erased by extensive restoration works in the second half of the 19th century. The architectural survey of the parish church of “Santa Maria” was carried out with a phase-shift laser scanner and a digital reflex camera (Z+F 5006h). 189 scans were performed for generating the 3D model of the church: 180 of them with high density and normal quality, lasting 5-6 minutes; the remaining ones with super high density and high quality, lasting 13-14 minutes. Vectorial drawings of plans and sections were then created from the 3D model. Thanks to laser scanner survay of the chuch, it was possible to highlight the singularity of the structure of the basilical body and the transept. The tilt of walls and columns, the variations in the thickness of the walls, the considerable deformations of some arches, the cracks and textures of the wall facing were thus shown. The information obtained attested an architectural structure created by complex construction events that over time have affected this building. The cnstructive singularities involve the medieval genesis of the building, the transformations during the following centuries and the following restoration works. These composite features are specific and common to every ancient building. This peculiar epistemological condition eschews from simplifications and requires deep and complex studies closely linked to the problems of conservation of the structures.