Virtual Unfolding and Visualization of Papyrus Packages

• Applicants: Dr. Daniel Baum; Professorin Dr. Verena Lepper
• Subject Area: Image and Language Processing, Computer Graphics and Visualisation, Human Computer Interaction, Ubiquitous and Wearable Computing
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 447883096

One of the best sources of information about the life and culture of our ancestors are their written documents. In museums and collections all over the world, there is a wealth of documents, many of them hundreds to several thousand years old, written in many different languages and on a variety of writing materials. Sheet-like writing materials such as metal sheets, parchment, papyri, and paper were often rolled or folded. Physically unfolding such documents to reveal their written content carries a high risk of permanently damaging the precious objects. For this reason, researchers have begun to access the contents of such objects using state-of-the-art tomographic techniques in combination with computational tools without physically opening the objects. In the case of rolled documents, this has been partially successful, but requires extensive work. Of all writing materials, papyrus probably poses the greatest challenge due to its inhomogeneous double-layer structure. Thus, even the virtual unrolling of papyrus scrolls, e.g. of the Herculaneum papyri, can be a great challenge. Still more difficult is the virtual unfolding of packages that were created by folding along several axes. In preliminary work, we have shown that virtual unfolding of papyrus packages is possible in principle, but can lead to large distortions that make deciphering the scripts impossible. Moreover, more complicated packages could not be unfolded at all with this first approach.We therefore propose a novel, model-based approach in which the entire unfolding process is guided by interactive visualization. While this approach aims at the greatest possible degree of automation, it allows expert knowledge to be included in each step. This will enable papyrologists to unfold even very challenging (papyrus) scrolls and packages with high quality. Instead of reconstructing the papyrus layers locally from the 3D image data, we follow a global approach by folding a double-layer mesh in exactly the same way as it was done for the real package. The folded mesh is then gradually adjusted to the 3D image by interactive mesh deformation and automated mesh-to-image registration. A key contribution to this will be an interactive volume rendering of the image data around the folded mesh, allowing real-time response to changes in position and thickness of the mesh. The volume rendering will be tightly coupled to the mesh deformation, allowing papyrologists to manipulate the mesh in real time with full visual control.Although our focus will be on papyrus packages, the approach will be general enough to be adaptable to other writing materials but also to other applications like the unrolling of batteries in materials research or the reconstruction of sheet-like structures such as membranes or interfaces in biology.

• DFG Programme: Research Grants
• International Connection: France, Saudi Arabia
• Cooperation Partners: Dr. Marc Etienne; Professor Dr. Markus Hadwiger