Unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microtomography

Dambrogio, J.; Ghassaei, A.; Starza Smith, D.; Jackson, H.; Demaine, M.L.; Davis, G.; Mills, D.; Ahrendt, R.; Akkerman, N.N.W.; Linden, D. van der; Demaine, E.D.

doi:doi:10.1038/s41467-021-21326-w

Persistent URL of this record https://hdl.handle.net/1887/3154422

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Centre for the Arts in Society (LUCAS)

Dambrogio, J.; Ghassaei, A.; Starza Smith, D.; Jackson, H.; Demaine, M.L.; Davis, G.; ... ; Demaine, E.D. (2021)

Unlocking history through automated virtual unfolding of sealed documents imaged by X-ray microtomography

Article / Letter to editor

Computational flattening algorithms have been successfully applied to X-ray microtomography scans of damaged historical documents, but have so far been limited to scrolls, books, and documents with one or two folds. The challenge tackled here is to reconstruct the intricate folds, tucks, and slits of unopened letters secured shut with “letterlocking,” a practice—systematized in this paper—which underpinned global communications security for centuries before modern envelopes. We present a fully automatic computational approach for reconstructing and virtually unfolding volumetric scans of a locked letter with complex internal folding, producing legible images of the letter’s contents and crease pattern while preserving letterlocking evidence. We demonstrate our method on four letterpackets from Renaissance Europe, reading the contents of one unopened letter for the first time. Using the results of virtual unfolding, we situate our findings within a novel letterlocking...Show moreComputational flattening algorithms have been successfully applied to X-ray microtomography scans of damaged historical documents, but have so far been limited to scrolls, books, and documents with one or two folds. The challenge tackled here is to reconstruct the intricate folds, tucks, and slits of unopened letters secured shut with “letterlocking,” a practice—systematized in this paper—which underpinned global communications security for centuries before modern envelopes. We present a fully automatic computational approach for reconstructing and virtually unfolding volumetric scans of a locked letter with complex internal folding, producing legible images of the letter’s contents and crease pattern while preserving letterlocking evidence. We demonstrate our method on four letterpackets from Renaissance Europe, reading the contents of one unopened letter for the first time. Using the results of virtual unfolding, we situate our findings within a novel letterlocking categorization chart based on our study of 250,000 historical letters
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digital humanities

correspondences

Brienne

Signed, Sealed, , Undelivered

computational tools

algorithm

early modern history