Hidden details in fifteenth century map revealed with multispectral imaging
Multispectral imaging has uncovered hidden text in a 15th century map of the world, shedding new light on the history of cartography. The study was carried out at Yale University’s Beinecke Rare Book and Manuscript Library where the map by German cartographer Henricus Martellus is displayed.
The Martellus map was drawn in 1491 and is considered the best contemporary cartographic representation of Columbus’ conception of the world at the time of his first voyage. It depicts the globe from the Atlantic Ocean in the west to Japan in the east. However, much of the text and other details are now illegible due to its age.
By studying the map at different wavelengths of light and then combining the images digitally, the worn text and other features such as river systems can be brought out and made legible.
The scientists captured 55 images of the map at different wavelengths, with the imaging equipment and expertise provided by The Lazarus Project at the University of Mississippi and the imaging team operating under the auspices of the Early Manuscripts Electronic Library.
Multispectral imaging is now increasingly used in art and rare document investigation – The Lazarus Project has used the technique to study documents containing William Shakespeare’s signature and damaged letters dating from the American War of Independence in the 18th century.
The Martellus map has been shown to bear similarities to Martin Waldseemüller’s world map of 1507 – the first map to apply the name 'America' to the New World. A study undertaken in 2012 using infrared and ultraviolet images revealed enough of the hidden text to show that the map was an essential source for Waldseemüller’s 1507 map. The information recovered through multispectral imaging will enable further study of Martellus’ influence on Waldseemüller.