3D replica of cherubs for the Church of San Luca in Pavia / Replica 3D di cherubini per la chiesa di San Luca di Pavia

The modeling and 3D printing of two cherubs stolen from the church of San Luca in Pavia around the mid-90s of the last century is the purpose of this project. It is an example of application of new technologies to art, in this particular case to replicate a stolen object and return it to its original home. It is the result of the degree thesis in Electronic and Computer Engineering by Adriano Cotta Ramusino, entitled "Photogrammetry for art: the cherubs of San Luca", supervisor: Prof. Virginio Cantoni.

not stolen cherubs The two white marble cherubs stolen from the high altar, made by the sculptor Fossati in 1684, were part of a group of four reliefs. They have never been found again and the balustrade has since then been disfigured. The idea of the CVML laboratory was born from the desire to return these artworks to the community of San Luca. Applying modern modeling and 3D printing technologies, the not stolen reliefs have been reproduced to print copies that can be returned to the city's artistic heritage.

The applied technique is photogrammetry, which uses information extrapolated from two or more two-dimensional images and, exploiting the rules of perspective, it allows to reconstruct a three-dimensional object.
Several fields benefit from the application of this technique: traditionally used in topography and cartography, in more recent times it has been of particular interest in the medical sector, where it is used to reconstruct organs or tissues in three dimensions, and - thanks to the widespread use of computers and digital cameras - it has become a widely available technique even at the customer level.

The process. The first step in photogrammetric reconstruction is a meticulous photographic survey. For this project, mounting a reflex camera with specially chosen optics, an image was taken every 15°, both on the azimuth and zenith axis. The finer details were photographed in additional targeted images, to achieve a more detailed final result.
The images obtained were standardized with Photoshop Lightroom Classic, before being inserted into Meshroom (Open Source 3D Reconstruction Software). This latter software identifies the position of the camera for each shot and using the perspective geometry and the chiaroscuro, it builds a cloud of points which are then joined into a mesh, which constitutes the starting 3D model. This is followed by a cleaning and optimization phase for printing, made with the Blender software.

3D models
The printing process. The ready-to-print models were entrusted to the 3D4MED laboratory, where the staff, using a 3D Systems printer ProJet® CJP 460 Plus, produced the prototypes. The printing technique used makes it possible to produce pieces in a material similar to plaster and it offers the possibility of creating color prints, a feature sometimes extremely useful.

risult
cherub1 in 3D

cherub2 in 3D