Henricus Martellus World Map c. 1491

Hidden Secrets of 1491 World map Revealed Via Multispectral Imaging

Mike Cummings | June 12, 2015

Henricus Martellus, a German cartographer working in Florence in the late 15th century, produced a highly detailed map of the known world. According to experts, there is strong evidence that Christopher Columbus studied this map and that it influenced his thinking before his fateful voyage.
Martellus' map arrived at Yale in 1962, the gift of an anonymous donor. Scholars at the time hailed the map's importance and argued that it could provide a missing link to the cartographic record at the dawn of the Age of Discovery. However, five centuries of fading and scuffing had rendered much of the map's text and other details illegible or invisible, limiting its research value.

<more at http://phys.org/news/2015-06-hidden-secrets-world-revealed-multispectral.html; related link http://www.spectralcameras.com/spectralcamerasupport (What Is Multispectral Imaging?)>