DOI: 10.26301/0x6p-vk89
title: Baptistery di San Giovanni in Florence - 2014

description: The laser scanning was performed using a Faro Focus 3D x130 laser scanner with 1â€“2 mm resolution (FARO 2017). The entirety of the Baptistery was documented using this method (Hess et al. 2018). Fourteen scans were taken on the exterior of the structure at ground level with an average of 28,083,564 points per scan; 13 scans were taken on the interior of the structure at ground level with an average of 43,789,216 points per scan; 21 scans were taken in the upper balcony level with an average of 7,005,528 points per scan; 14 scans were taken in the subterranean level where the wall of interest is with an average of 31,191,672 points per scan (Hess et al.2018). Physical targets were not required for alignment due to the large amount of details on the structure itself; this approach has been proven to be successful in previous literature (Napolitano and Glisic 2018). The scans were aligned using FARO Scene. Initially the scans were positioned by manually identifying mutual features in overlapping scan areas. Subsequently, automatic cloud-to-cloud alignment was utilized to align all scans and reduce any issues from manual registration. To calculate the alignment error, the distance is computed between common points in overlapping point clouds and then averaged for each section; the mean error was 1.2 mm. An image of the laser scan data for the foundation wall can be seen in Figure 3. Additionally, a Canon 5D DSLR was used to augment the existing data set with photographs.
From:

Hess, M., V. Petrovic, M. Yeager, and F. Kuester. 2018. Terrestrial laser scanning for the comprehensive structural health assessment of the baptistery di san giovanni in florence, italy: An integrative methodology for repeatable data acquisition, visualization and analysis. Structure and Infrastructure Engineering 14 (2):. doi:10.1080/15732479.2017.1349810
description: The Baptistery di San Giovanni, or the Florence Baptistery, is a minor basilica adjacent to the duomo in Florence, Italy (Figure 1; (2017)). As one of the oldest buildings in the city, this structure has changed in both form and function over time. While the earliest historical reference to the baptistery itself is in 897 AD, the foundations predate the superstructure; sections are from a Roman construction dating back to the 3rd century AD (Hess et al. 2018).

Having been at the center of art, history, and controversy throughout the evolution of Florence, the Baptistery di San Giovanni became an iconic monument of the city that is cherished by locals and tourists. To preserve such an old and complex structure requires a detailed and data-driven understanding of the forces at play; in the case of heterogeneous masonry structures, this task is frequently very difficult.

The Baptistery is a quasi-symmetrical octagonal structure with a corresponding series of eight curved ceiling panels that make up the cupola, or dome, of the building. The structure of this dome is comprised of an inner curved structure and an outer flatter structure that serves as the roof; these two dome shells are tied together with periodic masonry ribs. Beneath the Baptistery is a partially excavated Roman villa which reveals portions of the foundation that supports the Baptistery walls above.

Through the many years of its rich history, the foundation walls of this structure have incurred a large amount of cracking. In this article, a combination of laser scanning and finite-distinct element modeling (FDEM) are used to identify potential causes of this cracking on the southwest wall (indicated with a red rectangle in Figure 2) (Hess et al. 2018; Napolitano et al. 2019a). By identifying what most probably caused existing cracks on this structure, the best routes for preservation and stability analysis can be established.
From:

Hess, M., V. Petrovic, M. Yeager, and F. Kuester. 2018. Terrestrial laser scanning for the comprehensive structural health assessment of the baptistery di san giovanni in florence, italy: An integrative methodology for repeatable data acquisition, visualization and analysis. Structure and Infrastructure Engineering 14 (2):24763. doi:10.1080/15732479.2017.1349810
description: LiDAR - Terrestrial, Photogrammetry - Terrestrial, Ground Penetrating Radar (GPR), Thermography