Three textual works by Olaus Magnus (1490–1557) hold the key to the ‘compass’ on his invented island of Hvitsark, shown on his 1539 Carta marina. Although Olaus had little general understanding of the magnetic compass or of navigation in the Far North, he evidently did not intend the navigational device he drew on Hvitsark to represent a magnetic compass, but a sundial. His muddled ideas about the relationship between 12 wind-directions and direction-finding at sea by means of such a dial appear related to his second-hand information about a gnomonic navigational device used by the medieval Norse.

Several military and commercial platforms are currently installing GPS and inertial navigation sensors concurrently with the introduction of high-quality visual capabilities and digital mapping/imagery databases. This enables autonomous geo-registration of sensor imagery using GPS/inertial position and attitude data, and also permits data from digital mapping products to be overlaid automatically on the sensor imagery. This paper describes the system architecture for a Navigation/Electro-Optic Sensor Integration Technology (NEOSIT) software application. The design is highly modular and based on commercial off-the-shelf (COTS) tools to facilitate integration with sensors, navigation and digital data sources already installed on different host platforms.