Swarm knowledge in demand

Graz invites people to do puzzles for science

In the "Open Reassembly" game, anyone can try to reassemble the altar slab, which has been broken into 139 individual pieces.(Bild: APA/CGV - TU Graz)

Researchers from TU Graz and the University of Graz have digitized a broken altar slab from Lavant so that Internet users can put it together. The aim is to achieve what generations of archaeologists have so far failed to do.

The bishop's church at Kirchbichl in Lavant in East Tyrol is one of the most important early Christian monuments in Austria. The remains of this church, including fragments of a marble altar slab, were uncovered in the 1950s. In all these years, it has not been possible to completely reassemble the altar slab, which was broken into 139 individual pieces.

What experts have so far been unable to do is now to be achieved with the help of interested citizens: Researchers at Graz University of Technology and the University of Graz have created the interactive internet platform "Open Reassembly", where users can work together to reassemble the digitized fragments of the altar slab.

Even specialized algorithms can hardly solve the puzzle
"The fragments are largely textureless and partially eroded, which makes reconstruction extremely difficult," says Reinhold Preiner from the Institute of Computer Graphics and Knowledge Visualization at TU Graz. "It is not always possible to clearly determine whether two fragments fit together due to the erosion. In addition, not all fragments of the slab are still present. Therefore, even computer algorithms specializing in such objects cannot reliably solve this puzzle." The hope now rests on the swarm intelligence of interested internet users.

Digital twins from hundreds of photos and geometric data
For the project, the individual parts of the altar slab were digitized at the Institute of Antiquity at the University of Graz. "We took around 100 photos of each fragment from different perspectives and combined them with geometric data from measurements taken by a grazing light scanner," explains Stephan Karl from the Institute of Antiquities.

The digital twins of the fragments created in this way can be rotated in all directions on the "Open Reassembly" website and virtually put together with the other pieces. Participants can do the puzzles themselves and evaluate the adaptations of other players. Together, the hope is that the swarm will get closer to the solution step by step.

Uncharted territory
However, the project is also relevant beyond the archaeological puzzle: "There are already approaches to computer-aided reassemblies in computer science: they are usually fully automated, occasionally also involving individual users, but always locally," says Reinhold Preiner. "By involving the general public in such a reassembly process via the Internet, we are largely breaking new ground."

Searching for optimal conditions for cooperation
Reinhold Preiner and Stephan Karl want to find out whether the collaborative approach to such a complex geometric-combinatorial problem delivers a solution that is highly likely to be correct, even without specialist archaeological knowledge. On the internet platform, users are automatically divided into larger and smaller groups and receive varying degrees of technical assistance.

"By analyzing solution progress, processing time and solution efficiency, we want to find out which framework conditions are most conducive to the collective reassembly process," says Reinhold Preiner.

All you need to participate is a desktop computer with Internet access, mouse and keyboard. No personal data is collected during registration.