Revealing ‘invisible’ poetry by W. H. Auden through computer vision: Using photometric stereo to visualize indented impressions

This article explores the use of computer-vision technologies in the context of digitally editing and researching letters and literary papers by the British-American poet W. H. Auden. Two documents in the previously inaccessible ‘Auden Musulin Papers’ contain colourless indented typewriter impressions of poetry. These impressions result from the papers’ original use as ‘backing sheets’, inserted into a typewriter below those sheets of paper on which Auden typed his poetry. Subsequently, these backing sheets were reused in the poet’s ‘working correspondence’ to Welsh-Austrian writer Stella Musulin. While standard image-digitization technologies fail to capture these 3D indented impressions, they can successfully be represented by means of Photometric Stereo, which has been fruitfully employed in the research of 3D cultural-heritage objects. Following a detailed outline of this method, this article demonstrates how Photometric Stereo can help to reconstruct poetry that has survived only in the form of indented impressions. Thus, the case study illustrates how computer vision can contribute to our understanding both of ‘poetic’ practices of composition and revision as well as of ‘material’ writing practices. It also has wide-ranging implications for re-conceptualizing sheets of paper as 3D objects in the research of literary documents from the twentieth century.