![]() With the resolution of commercial table-top instruments available today, the procedure may simply be to sort out candidates for tomography by X-ray fluorescence and to decide on the imaging technique most appropriate to distinguish ink from substrate. Therefore, there is a strong need to develop a non-destructive method that allows scholars to access the hidden texts of as many objects as possible. With regard to papyri, this applies particularly to objects that are unreadable, since mechanical unrolling or unfolding would damage them. ![]() Many objects, excavated in different archaeological campaigns, were then often buried again in museums’ depots. In the investigation presented here, we report on the result of virtual unfolding performed on a mockup papyrus that was lettered with very highly absorbent red ink, made from cinnabar and minium, to demonstrate the algorithmic procedure and to separate it from the complex problem of uncovering the script on ancient papyri. ), the recovery from folded documents represents an even bigger challenge. While the recovery of text on a scroll, no matter how badly the scroll had been distorted or compressed, has been achieved in various cases (e.g. Second, virtual unfolding is hampered by physical separation of the two layers that can often be observed. First, the stripes of the cut papyrus stems, which are arranged in two layers with the orientation of the stripes being orthogonal to each other, complicate the distinction between writings and substrate for iron gall ink or less X-ray absorbent inks. In contrast to more homogeneous material, such as metal foils or even parchment, the structure of papyrus poses further challenges. īesides the mere detection of the script, the reconstruction of the text as a whole poses a challenge to the mathematical treatment of the tomographic data set. Most recently, even letters written with carbon ink could be identified in carbonized papyri by phase contrast tomography. Due to recent improvements with respect to sensitivity and resolution, a few spectacular disclosures of hidden texts have been possible by X-ray tomography on heavily corroded metallic foils with imprinted writings and on parchment written with inks containing heavy elements, typically Fe. Some of these writings are hidden in rolled, folded or scrambled documents. ![]() Our best sources for information about the culture of our ancestors and predecessors are their writings. In the case of the folded papyrus, our approach represents the first attempt to address the unfolding of such complicated folds. In this work, we present the results of applying our approaches to mockup papyri that were either rolled or folded along perpendicular fold lines. We have applied our software framework to several papyri. In the second stage, the papyrus is flattened, which requires the definition of a medial surface. To minimize distortions at this stage, we apply the method of moving least squares. In the first stage, we virtually invert the physical folding process step by step until the partially unfolded package is topologically equivalent to a scroll or a papyrus sheet folded only along one fold line. Unfolding of packages is done in two stages. In addition, it allows us to cope with challenges posed by the structure of ancient papyrus, which is rather irregular, compared to other writing substrates like metallic foils or parchment. This provides the necessary flexibility to enable the unfolding of even complicated and partly damaged papyrus packages. Our algorithmic approaches are combined with manual interaction. We demonstrate a way to get access to the hidden script without physical unfolding by employing computed tomography and mathematical algorithms for virtual unrolling and unfolding. Physically unrolling or unfolding these packages might severely damage them. Ancient Egyptian papyri are often folded, rolled up or kept as small packages, sometimes even sealed.
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