Clock Tower in University of Pavia

Original name

Clock Tower

Geographic Area

Piazza Leonardo Da Vinci, Pavia, Italy

Reference Project

Geometric and material 3D survey of the Clock Tower of the Central University of Pavia. Morphological analysis and monitoring of plastic deformations

Site description

The civil towers in Pavia are a distinctive element of the city’s architectural heritage, dating back to the Medieval Age as statement of the lordship’s power and wealth. They constitute singularities in the urban landscape, with out-of-scale vertical development, whether in the original morphology or altered by subsequent actions. Furthermore, they are embedded in a dense urban fabric and therefore they are naturally associated with local risks for the safety of the urban setting and its users. These peculiarities require accurate and complex documentation practices and foster monitoring and morpho-material mapping as preliminary actions to their conservation. The knowledge analysis that has been developed on the case study of the Clock Tower aims to systematize a documentation strategy for delivering an accurate and updated conservation status of the wall surfaces. Digital survey outputs are then developed as diagnosis tools to support interventions procedures, by highlighting deformations and deteriorations that could cause structural instability.

Credits

Promoted by
Technical Informative and Safety Area of the University of Pavia

Coordinator
Sandro Parrinello

Partnership
UNIPV, University of Pavia

Survey Activities

Laser Scanner
Raffaella De Marco

UAVs Photogrammetry
Raffaella De Marco
Francesca Picchio

Terrestrial Photogrammetry

Raffaella De Marco
Francesca Picchio

Post production Activities

2D Drawings
Raffaella De Marco
Anna dell'Amico
Silvia La Placa

3D Model
Raffaella De Marco

Deformation and Surface Alteration Analysis
Raffaella De Marco
Alessia Miceli

  • Gallery
  • 3D Model

Documentation Methodology

The survey was carried out between December 2019 and January 2020 aimed at obtaining a reliable morpho-metrical database on which to perform analyses of structural instability and surface decay. The singular structural form, unusual dimensions and the relationships with the physical built environment led to opt for tailored and specifically calibrated survey methodologies to obtain accurate and reliable data. The survey was conducted with Terrestrial laser scanning (FARO Focus S150), UAV mapping and camera mapping. Located within the dense urban area, the tower posed difficulties in maintaining a high-quality dataset for the higher portion, given that the quality and density are influenced by the distance from the object. To resolve this issue a double path of acquisition was adopted: for each medium quality scan (360° x 320°) a partial dataset with limited angle (variable angle x 320°) was performed, allowing to obtain increased density in the point cloud (range of density between 1:1-1:2, high resolution 4x, for approximately 7 minutes scan). The UAV survey activity was accurately planned for controlled distance from the shooting surface (2m with a 12 Mpixel camera), and hovering. The shooting was performed according to a control grid with at least 30% overlap of width/height of the photographs.

The high-quality and high-resolution photographic dataset allowed for generating rectified photoplanes on which to perform automatic vectorization of the wall texture, obtaining complete and reliable representation of the dimensional and material characterization of the tower’s fronts. The resolution of the point cloud allowed for the analysis of the point’s deviation from a defined geometrical plane, resulting in identify macroscopic deformations affecting the entire block and local alterations related to depressions and patinas. The combination of both results allowed for complete mapping of deterioration phenomena affecting the tower’s external surfaces, with particular focus on the two-sided clock, affected by falling debris in late 2019.

Bibliography

Raffaella De Marco, Alessia Miceli, Sandro Parrinello (2020) An assessment on morphological survey calibration and the automation of digital drawing for the reliable documentation and conservation analysis of out-of-scale buildings. Imeko TC-4 International Conference on Metrology for Archaeology and Cultural Heritage MetroArchaeo2020 October 22-24 2020 ResearchGate

Raffaella De Marco (2020) Mapping solutions and reliability control in UAV’s photogrammetry for structural emergency. The multi-instrumental survey of the Clock Tower in the historical complex of University of Pavia, in: S. Barba, S. Parrinello, M. Limongiello, A. Dell’Amico (a cura di) D-SITE Drones - Systems of Information on culTural hEritage. For a spatial and social investigation Pavia University Press, Pavia 2020, pp. 238-247 ResearchGate