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Cambridge University Library

 

Large scale digitisation – but not as you know it!

The problem: Not every item will fit on standard digitisation cradles, or even specialised ones…

The Solution: Get creative!

When the University Library’s Digital Content Unit was asked to digitise a series of maps, the largest of which was over 4m x2.5m, they had to think outside the box in order to achieve results that were up to the usual high standard.

Previously the only way to do this would have been to shoot from further away, which would not only result in a lower resolution image, but the studio ceiling is only so high! Or you could use a wide-angle lens, but that would result in an extremely distorted image. Or you could shoot sections and manually stich the images together, which might work on a modern/robust map, but handling fragile hand painted cloth maps that are over 150 years old isn’t a simple thing. In fact, we’re not even certain anyone had ever looked at the whole of the largest map rolled out in its entirety before, since you’d need extremely long arms to paint it and an extremely big table on which to use it – fortunately, since these maps are most likely for the purposes of taxation, it is unlikely the original users would need to view the whole thing at once. But we do!

So, in collaboration with an engineering company, the photographers set about custom building a digitisation work station that was up to the job. The result is a huge mechanised flat surface, the XYZ Table, that is roughly 1.2m x 1.7m (that’s twice the size of A0!) with a fully adjustable camera and lighting rig. This is controlled by an especially designed computer that carefully and accurately moves the surface in a grid pattern parallel to the camera. The camera captures a big enough overlap of each quadrant that the image tiles can then be reliably stitched together afterwards.

This workstation works so successfully that the resulting image of the largest of the maps is actually too big to process and display on Cambridge Digital Library at present – it’s about 90,000 by 70,000 pixels large!!!

Keywords
Map, large, digitisation, stitched, images, engineering, XYZ Table, tiled

Key People
Maciej Pawlikowski, Amélie Deblauwe, Scott Maloney

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