Jacob van Deventer (cartographer)

Van Deventer was among the first to make systematic use of triangulation, a technique whose theory was described by Gemma Frisius, one of his teachers at the University of Leuven.

Jacob van Deventer was among the first to make systematic use of triangulation, a technique whose theory was described by his contemporary Gemma Frisius in his 1533 book, Libellus de locorum describendorum ratione.

In 1559, he was tasked by King Philip II with the project that was to become his life's work: the systematic cartography of all cities of the Netherlands.

In the course of fifteen years, he created between 250 and 260 city maps, covering an area from Friesland to what is today the north of France, and reaching into Luxembourg and the west of Germany.

The second stage was a "main chart" (netkaart or hoofdkaart), representing a cleaned-up elaborated version of the previous minute map, with texts in Latin.