Sanxingdui is an archaeological site and a major Bronze Age culture in modern Guanghan, Sichuan, China. Largely discovered in 1986, following a preliminary finding in 1927, archaeologists excavated artifacts that radiocarbon dating placed in the 12th–11th centuries BC. The type site for the Sanxingdui culture that produced these artifacts, archeologists have identified the locale with the ancient kingdom of Shu. The artifacts are displayed in the Sanxingdui Museum located near the city of Guanghan.

                                                               --- Wikipedia

Sanxingdui Bronze Statues

The 3D scanning of Sanxingdui gold mask

Sanxingdui is an extraordinary discovery. Bronze statues, bronze masks, gold masks and other rare treasures, which are all carrying the glory of the past Sanxingdui civilization. It's really an honor for ZG to participate in the excavation and protection of Sanxingdui cultural relics. Leveraging ZG's 3D measurement technology, the data acquisition, protection and restoration of cultural relics have become more efficient and accurate than ever before.

The gold mask, one of the most famous Sanxingdui relics, has an intricate surface which is impossible to be measured by traditional methods, but with ZG's Smart Handheld Blue Laser 3D Scanner---RigelScan Plus, the situation is different.

                                           Preparation Before 3D Scanning                                                                                                                                   RigelScan Plus and the Scan Data

 

1. Preparation before the 3D scanning

RigelScan Plus can scan the surface of the gold mask without touching it, which is known as non-contact measurement, and there’s also no need to place markers on its surface, so the damage to the gold mask is minimized.

To prepare the 3D scanning environment for RigelScan Plus, the engineers started by laying out a series of reflective markers and magnetic cubes around the mask. This provided the engineers with a reference frame during the 3D scanning process.

2. Real-time 3D scanning and data acquisition

Once the first step was completed, a process that took less than two minutes, the mask was ready to be scanned. Comprising 22 high-definition blue laser lines, RigelScan Plus can scan any kind of surface extremely fast, its scanning speed can be up to 1,350,000 measurements/s. The laser lines can automatically adapt to the surface’s reflectivity and color, which removed the need to apply anything beforehand, much to the relief of the engineers involved.

Throughout the scanning process, the engineers fully utilized ZG's 3D data acquisition software---ZGScan, an easy-to-use scanning software that manages the complete scanning process. The scanning process can be displayed on the software in real time, so the engineers could quickly check the 3D scan’s quality and the areas needing more data or had been missed conveniently.

Gold Mask Scan Data

3. Post-processing and model generation

When the scanning process was completed, the scanned data can be post-processed on the software, such as mesh optimization, simplification, best-fit, filling holes, etc. After that, a perfect digital model of the gold mask was generated. The 3D data can be used for 3D visualization, 3D printing, 3D display, etc.

4. Art Mapping

As the Smart 3D Texture Mapping Software self-developed by ZG Technology，Art Mapping is the one of the most advanced texture mapping software in the world due to its high efficiency. It realized the auto-registration between 3D data and 2D colorful pictures. More than thousands of images can be automatically mapped at one time.

To apply the Art Mapping technology on the digital model of the gold mask, pictures of the gold mask should be taken by a camera from different directions to build a regional network, then register the network with 3D point cloud data to generate a model with texture.

                                              Picture Taking of Gold Mask                                                                                                        Ideal Result of Art Mapping

This data will be fundamental in providing the Sanxingdui Museum with a highly accurate digital representation of the gold mask that can be used for 3D visualization and research purposes. Of most importance, the data will serve to assist scientists and conservators in their research of the history of Sanxingdui civilization.

How can 3D scanning technology help in cultural conservation?

1. Restoration

As a precious historical and cultural heritage, cultural relics are extremely fragile and non-renewable. Without basic data, once they are damaged due to various accidents, it will become extremely difficult to repair or restore them.

1.1 To help the restoration of damaged historic building

On 15 April 2019, a fire broke out beneath the roof of Notre-Dame de Paris cathedral in Paris. By the time the structure fire was extinguished, the building's spire had collapsed, most of its roof had been destroyed and its upper walls were severely damaged.

After French president Emmanuel Macron announced that the cathedral would be restored by 2024, a game, Assassin’s Creed Unity, was found to be able to provide some important help because it has a 3D model of the cathedral. This reflects the importance of 3D scanning technology in the restoration of historic building. If Notre-Dame de Paris has been 3D scanned by a 3D scanner before, the restoration process would be much easier.

1.2 To help the splicing of cultural relics fragments

During the excavation, some cultural relics have been broken into many small pieces and need to be spliced. When using the traditional way to splice the fragments, it takes a lot of time to figure out a perfect splicing way, and the cultural relics are likely to be damaged again. When using the 3D scanning technology, the process will be much easier. The fragments can be 3D scanned and virtual spliced, and then the actual fragments can be spliced according to the spliced 3D model.

The Splicing Process of Cultural Relics Fragments

1.3 To help the conservation of mural

As a precious cultural treasure, murals are very fragile and need to be conserved carefully. However, it is difficult to find out the changes of murals only by visual inspection, in this case, the 3D scanning technology would be utterly helpful. The changes in murals can be easily detected when comparing the before and after scan data.

The Change Detection of Mural

2. Digital Archaeology

With the help of 3D scanning technology, the traditional archaeology has now evolved into a new version---digital archaeology. Digital archaeology is not only an opportunity for the cultural conservation, but also the trend of the development of archaeology in the information age. Digital technology can not only help archaeological excavation, but also digitize archaeological discoveries and provide information support for follow-up research, protection, and display.

3D scanning meets Sanxingdui is a wonderful dialogue between modern technology and ancient civilization. Besides the dialogue with the past, ZG Technology shall also face the future, as we always say, innovation never ceases.