Photographing a spherical surface systematically and accurately is no easy task. The challenges involved include controlling luminosity (chiefly glare) and standardising image capture (register).
To overcome these hurdles, Eric Sapin and Quentin Milliet, both specialists at the School of Forensic Science (ESC), came up with an original system. The spheres’ rotation was controlled by two cross lasers equipped with levels. The beam of one laser passed through the camera’s viewfinder to centre each image perfectly. The other beam was projected to the side to control the globes’ horizontality and verticality permanently.
The pictures followed the latitudes and longitudes starting from Mercator’s prime meridian, which passes through Fuerteventura in the Canary Islands (14.1° W on today’s globes). The 42 final images, centred on selected intersections in the grid, covered each globe entirely.
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- Procédure pour la photographie des globes de Mercator : Procedure for photographing the Mercator globes, Alexandre Hirzel, IT Centre, UNIL | University of Lausanne.