Borders and Panoramas in Early Modern Portugal: Integrating Architectural and National-Scale Spatial Analyses with 3D GIS

In March of 1509, King Manuel I of Portugal sent a squire named Duarte de Armas on an important mission. Over the following seven months, Duarte traveled by horseback along Portugal’s border with Spain – a historical buffer-zone known as the Raia – and created two panoramic drawings from opposite sides of 56 different Portuguese border castles and towns. Individual drawings from Duarte’s bound “Book of Fortresses” are often held up as useful illustrations of pre-artillery Iberia, but the artist’s seemingly arbitrary sense of perspective causes it to be overlooked as a holistic document. Using a combination of photogrammetry, 3D modeling and GIS techniques, this presentation will reveal that Duarte’s slippery medieval / early modern perspective was intentionally applied to create the earliest “map” of the limits of Portugal. Duarte de Armas’ 57 castles may form a strikingly familiar chain along the Spanish-Portuguese border when they are visualized in cartesian space, but this view of the frontier bears little resemblance to the panoramic drawings that Duarte drew from more than a hundred positions in 1509. In the end, the Book of Fortresses project advocates for an embrace of the strengths of a 3D GIS system to orient and study historical panoramic drawings in the vertical plane much in the same way that historical maps have long been georeferenced and studied in the horizontal plane.