Preserving the Sacred: 3D Scanning and Replicating the Sculpture of Sainte Anne d’Auray

The sanctuary of Sainte Anne d’Auray stands as a testament to faith and history, attracting thousands of pilgrims annually. However, the centennial sculpture of Sainte Anne d’Auray is exposed to the wear of time and the fluctuating weather when displayed outside annually. This case study explores the innovative approach taken to preserve the sculpture by creating its digital copy using the state-of-the-art optical 3D scanning system TrackScan-Sharp and 3D color scanner 3DeVOK.

The Sculpture of Sainte Anne d’Auray is a significant religious artifact located in The commune of Auray, in Brittany, France. This commune is renowned as the third most popular pilgrimage site in France, following Lourdes and Lisieux. The sculpture is part of the rich heritage of the sanctuary, which has been a place of pilgrimage since the 17th century.

3D Scanning the Sculpture “Statue de la Dévotion” of Sainte Anne d’Auray

The primary objective was to create precise replicas of the cherished sculpture “Statue de la Dévotion” and its accompanying arch, both of which are over a century old. The sculpture measures 1m in height and is intricately carved from wood, while the arch spans dimensions of 2x2x2.5m. Additionally, several accessories, including a crown and necklace made from precious materials, required digitization.

Laser scanning and digital 3D models can aid in the preservation, restoration, and digital representation of cultural relics, ensuring authenticity and precision. This technology allows for the meticulous recording of an artifact’s shape, texture, and even color, creating a comprehensive digital twin that can be used for various purposes.

Challenges for Measuring the Sculpture and Accessories

Detail Capture: Ensure that the finest details are meticulously documented.

Non-Invasive Technique: Employ a non-invasive, target-free approach to preserve the integrity of the precious sculpture.

On-Site Scanning: 3D scanning the sculpture at the sanctuary to avoid transportation or potential damages.

Versatility: Manage a diverse array of artifacts, ranging from expansive arches to the delicate intricacies of crowns and necklaces.

Scantech’s 3D Solution for Cultural Heritage Preservation

Scantech’s reseller BTRD3D employed the optical 3D measurement system TrackScan-Sharp and 3D color scanner iReal M3 for the project to help with cultural heritage preservation.

Optical 3D Measurement System TrackScan-Sharp

TrackScan-Sharp was used for its large-volume measurement, exceptional accuracy, and detail capture capabilities. TrackScan-Sharp allowed the operator to scan the sculpture at various angles without the need for targets or physical contact, which was critical to avoid damaging the artifacts’ surfaces.

TrackScan-Sharp optical 3D measurement system, featuring the portable i-Scanner and the innovative i-Tracker, is designed for precision measurement of large-scale parts. It boasts a remarkable tracking distance of up to 6 meters, an expansive volumetric range of 49 m³, and a high volumetric accuracy of up to 0.049 mm within 10.4 m³.

iReal M3 3D Color Scanner

iReal M3 3D color scanner was also used to capture the full color and texture of the sculpture. Its infrared laser and structured-light modes enable smooth 3D data acquisition in different applications, be it scanning humans or objects, inside or outside. This combination allows for detailed reproduction of textures and colors, closely mimicking the original appearance of the scanned object.

3D Scanning and Data Processing

Arch Scanning: Five high-resolution scans at 0.7 mm were conducted in about 3.5 hours. The data was merged in PolyWorks, resulting in a total of 172 million data points.

Statue Scanning: A single scan using the super coordinate conversion mode was completed in 40 minutes at 0.1mm resolution, yielding 80 million points.

Color Capture: An additional scan with 3DeVOK provided color information in just 10 minutes at a resolution of 0.25 mm.

Accessories Scanning: High-resolution scans at 0.06/0.075mm took 1.5 hours to complete.

Data Treatment and Enhancement: Following the 3D scanning, the operator processed the point clouds to ensure that the digital model can represent the original sculpture at high fidelity.

Digital Sculpting and Modeling: The final phase involved digital sculpting and modeling to produce exquisite models and accessories, primed for 3D printing.

Advantages of Scantech’s 3D Solution

Precise Details: With powerful hardware and software, TrackScan-Sharp delivered high-precision measurement results with an accuracy of up to 0.025 mm and ensured that even the most intricate details were captured. Its software managed several dozen million points on a standard computer. It enabled the operators to reproduce the sculpture that stay pretty faithful to the original piece.

Non-Invasive 3D Scanning: Thanks to TrackScan-Sharp’s optical tracking and 3D scanning, no targets or physical contact was needed during the process, which preserved the integrity of the sacred objects.

On-Site Scanning: TrackScan’s portability allowed for direct scanning within the sanctuary. It was insensitive to cold and humidity, which enabled it to use right on the site even in harsh conditions.

Versatility: The blue laser excelled across all surfaces including the reflective surfaces. Due to its robust algorithm, TrackScan-Sharp efficiently handled objects of varying sizes, from the large arch to the necklaces to the minute details of the crown, which are less than 2mm. Besides, it is easier to scan on every angle no matter if the shapes are too thin or flat.

True-color Texture: iReal M3 can fulfill the demand of 3D data acquisition of multiple sizes and materials in various scenes thanks to its dual infrared lasers. Combined with its 3D mapping software, it also allowed operators to capture true-color and detailed textures.

Conclusion

One of the primary benefits of this approach is the ability to capture precise 3D data without physically interacting with the fragile artifacts which come in different sizes. This non-invasive method helps prevent further deterioration caused by handling. Moreover, in the event of damage or loss, the digital models and 3D printed models provide a valuable reference for accurate reconstruction.

The Scantech 3D scanning project at the Basilica of Sainte Anne d’Auray not only preserved the physical essence of the artifacts but also opened a new chapter in the heritage conservation and replication. The successful replication of these sacred items ensures their legacy for future generations, safeguarding the basilica’s historical significance.

Image Rights: btrd3d / Cecile Lothodé, not allowed for copy or reuse without mentioning the authors