Preserving art treasures in digitalised 3D imagery

Scientist Martin Ritz watches his monitor as a replica of the Bust of Nefertiti is scanned at the Fraunhofer Institute in Darmstadt, Germany. Scientists have developed the 3D scanner with the two semi-circular gantries to create perfect records of the shape of precious art treasures.

By Maren Hennemuth

The Bust of Nefertiti must take a ride on a conveyor belt so that a copy of it can be saved for the ages, says a team of experts on 3D copies.

The idea is that once a work of art has been scanned in 3D, its outer shape will be preserved digitally, even if war or disaster destroys the original. Worse comes to worst, at least a replica could be made.

Such a scanner already exists in Germany. It was developed by the Fraunhofer Institute’s graphic data processing unit in Darmstadt, a city near Frankfurt. If it goes into regular production, it could begin making copies of original art treasures quickly, without the hassle of taking plaster casts.

The lab has already tried the routine with Nefertiti, a depiction of a very beautiful pharaonic queen. They did not a get a loan of the original, which is one of Berlin’s most prized art treasures and is too fragile to be removed from the capital’s Egyptian Museum.

Instead, they did their experiments with a commercially available 1:1 copy of the bust.

The commercial copies take months to make. Fraunhofer Institute’s scanner, developed by a team of scientists led by IT specialist Pedro Santos, took just a few minutes to generate the three-dimensional digital image of the bust. Any similar object would take the same amount of time.

“There are certain countries that already realise they cannot preserve their cultural heritage,” said Santos in a sly dig at Germany, which spends vast amounts to preserve its past, but still suffers setbacks.

Much of Germany’s heritage was destroyed in the Second World War, despite the country’s passion for heritage. Within the past five years, a major archive repository has collapsed, taking with it priceless documents. The cause was unnoticed subsidence under the building’s foundations in the city of Cologne.

A decade ago, a historic library in the city of Weimar was gutted by fire, ruining 50,000 books from the 17th and 18th centuries.

Digital copies are now recognised as the best insurance against such unforeseen circumstances.

They can be used to make replicas, which can be loaned easily and can make the hidden part of a museum’s collection virtually accessible to the public.

“On average, a museum artefact is only put on display once every 10 to 15 years,” said Santos.

Darmstadt’s scanner will help make museum collections more accessible to the public. The first prototype cost about half a million euros ($660,000) to build, but the researchers expect the price to go down considerably once the scanner goes into series production.

Other ways to produce 3D scans exist, but the Darmstadt researchers say the existing machines can take up to 24 hours to scan just one item. Their scanner is faster. Deputy project leader Martin Ritz said, “With our method, objects of 60 by 60 centimetres can be scanned in just a few minutes.”

On the conveyor belt, the Nefertiti replica is pushed beneath two semi-circular gantries.

The inner arch has nine sources of light, while the outer one has an equal number of cameras. With a loud mechanical buzzing sound, the arches move over the bust, stopping briefly at various points in order to take pictures from all sides.

“When I take pictures with these nine cameras from nine different angles, I get 81 pictures in all. These are then used to calculate a geometric reconstruction,” Ritz explained.

Following the scanning process, a computer monitor shows the incomplete colour digital imagery of Nefertiti. The gaps show as black areas. Those are the spots not yet “seen” by the scanner, which is the reason that the object must continue its ride on the conveyor belt, automatically coming to a halt before a robotic arm bearing a second scanner.

“At this position, all the remaining gaps in the 3D model will be fleshed out,” Ritz explained. Once the scan is completed, the digital image appears on the computer screen and can be transferred to a database. After the meta-information is added, the scan can be put on the Internet for global access.

This begs the question: why go to a museum if you can see a digital replica on the Internet?

Hans Lochmann, spokesman for the museum science conference of Germany, believes digitisation will not deter museum visitors.

“The original has a completely different aura,” Lochmann said. “You get to see the real thing.”

Lochmann believes it is science and scholarship that will primarily benefit from digital copies. Modern experts expect access to information on the web, and libraries, museums and archives have to keep up with that demand.

Even so, it could be some time before the Fraunhofer Institute’s scanner is put on duty in a museum.

Right now it is going through comparative tests. The researchers are sending students to museums in Berlin and in Frankfurt to perform digital 3D scans using existing methods.

Later, the same objects will be scanned with the Fraunhofer prototype. If the new device is reliable, faster – and cheaper – it stands a good chance of becoming the next-generation scanner. -DPA