Historical materials are important materials for historical research, which help posterity to understand, explain and reconstruct the traces of historical process.
Among many historical materials, letters are an important one.
This method was regarded as the foundation of global communication security at that time.
Jana dambrogio, the librarian of MIT, once introduced this method
Yes, scientists have perspective!
On March 2, 2021, the related research results were published in nature communications, a sub Journal of nature, entitled unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microscopy.
The authors are from MIT (library, computer science and Artificial Intelligence Laboratory), Adobe R & D center, King's College London, Queen Mary University, Utrecht University, Leiden University and nemegen University.
According to MIT's official website, this breakthrough research is the result of cross-border and interdisciplinary cooperation among historical data protectors, historians, engineers, imaging experts and other scholars.
The researchers restored a letter labeled db-1627: it was written on July 31, 1697 by Jacques sennacques, a French businessman. In the letter, he asked his cousin Pierre Le pers for a copy of Daniel Le pers' death notice.
It is worth mentioning that before the calculation and analysis, the researchers only knew the name of the recipient written on the surface of the parcel.
What the research team used is an automatic calculation flattening algorithm.
This paper introduces that the computational flattening algorithm has been successfully applied to X-ray micro tomography of damaged historical documents, but it is still limited to scrolls, books and documents that have only been folded once or twice.
The idea of the research team is to reverse engineer the letters, that is to say, the letters themselves are the key data sets to study the historical communication security methods.
However, based on a special design, letters can only be opened at the intended destination. So to design a system, researchers have to infer from open letters.
The following figure shows the four parcels that the team mainly studied.
As shown in the figure below, without any prior information about the folding shape of the packet, this method generates the following results:
3D reconstruction of folded letters
The corresponding two-dimensional reconstruction represents its plane state
Mapping between 3D and 2D
The surface of the bottom layer of the letter
A flat image of each packet crease pattern
The process is simpleFirstly, the letters were scanned by X-ray micro tomography technology to obtain three-dimensional simulation.
Then the algorithm is used to identify and distinguish each layer of the letter: the principle of this step is that ink and letter paper will form different contrasts, and the content of the letter will be displayed.
At present, this algorithm has been open source（ https://github.com/UnlockingHistory/virtual-unfolding ）。
For historians and conservationists, even the creases and crevices of letters are valuable evidence. Therefore, it is a great progress in the study of historical documents to be able to obtain the contents of letters without damage.
Perhaps the greatest significance of this research lies in the integration of algorithms with other disciplines and the promotion of research and development in other fields.
As Nadine akkerman of Leiden University, one of the co authors of the paper, said: what we have achieved is not only to open letters that cannot be opened, but also to read hard to read contents. We show how real interdisciplinary work can break the boundaries and investigate what the humanities cannot solve independently.