Methodology for 3d Acquisition of Highly Reflective Goldsmithing Artefacts

Abstract

The goldsmithing pieces conserved in museums are fragile objects whose accessibility for both research and mediation purposes lacks dematerialized systems for the safe handling of objects. The research presented is part of the e-thesaurus project whose main objective is to improve the accessibility of masterpieces of goldsmithing -produced during the medieval period in the northern regions of France and today's Belgium -both for research and mediation purposes. The methodology for 3D acquisition of objects with high levels of details and reflective properties must be further developed and affirmed in order provide controlled datasets that are suitable for researchers of the field and accurate for mediation application. The proposed project is the result of a collaboration between the IRHiS UMR CNRS of the University of Lille and the University of Liège. The proposed methodology leads to the 3D reconstruction of masterpieces of goldsmithing. The models developed serve as a basis for a mediation through holographic representation. They recently participated in an exhibition in the Treasure of the Cathedral of Liège museum.* Corresponding author the reliquary cross of Clairmarais Abbey and a pyx (box to keep the consecrated Host), see Figure 1. These three objects were produced between the end of 12 th and the first decades of 13th century. They were chosen because of their geometric complexity and the large number of different materials they combine.

Digital Replicas of British Museum Artefacts

“…(Chen et al 2007) analysed the emission of light rays in disordered waves from light sources such as LED, light bulbs, and natural light, and affirmed the usefulness of polarising filters applied to the projectors and the camera. Depending on the reflectivity materials and richness of details requested in the 3D reconstruction, cross-polarised light conditions are strongly suggested, using combined filters for led lighting systems and flashes and controlling the polarisation direction (Hallot & Gil, 2019). The same authors assess the practical use of colour chart calibration to avoid random colour variations, especially when it is essential to maintain the reliability of the radiometric values of the models.…”

“…Therefore, to ensure consistent and homogeneous illumination, two LED panels (by LUPO) equipped with diffusers and four additional flashes mounted on a ring around the camera lens have been used. Additionally, the four flashes have been covered with a polarised filter: the same filter was installed on the camera lens to minimise light reflections fine-tuning the polarised filter orientation (Hallot & Gil 2019). A remote-release device was used to avoid blurred or smoothedout images, with an appropriate set of ISO, lens aperture and acquisition time settings.…”

Photogrammetry as an Access Tool: A Case Study of Small Collections From the Evansville Museum of Arts, History & Science

“…Lighting setup and needs will change depending on artifact shape, size, type, and material. Those with reflective surfaces, such as burnished ceramics, metals, or glass, require diffused lighting to eliminate glare (Hallot and Gil 2019).…”

Cross-Polarized SfM Photogrammetry for the Spatial Reconstruction of Challenging Surfaces, the Case Study of Dobšiná Ice Cave (Slovakia)

“…In photogrammetry, scientific papers dealing with such problematic surfaces were focused on enhancement techniques using cross polarization to document reflective surfaces either in general [31] or for archaeological findings [32,33], to document painting restoration with the detection of changes based on cross polarization [34], or for the 3D reconstruction of highly reflective historical artefacts [35]. However, cross polarization is not widely used in photogrammetry, although it has been known for decades and is well-established in some fields.…”