A person stands in a garden with topiary trees and trees. It looks out over the medieval building at its core. The person uses a remote control to control a drone that hovers in the air directly in front of them. — Fig. 1 Leer, Harderwykensteg 21, Harderwykenburg during the flight with a drone (Photo: M. Mennenga, NIhK).

The 3D model of the castle captured by the drone can be seen in an animation. The model shows the facades and the roof of the castle and rotates 360°. — Fig. 2: Animated 3D model of Harderwykenburg Castle (Modelling and graphics: M. Mennenga / P. Frederiks, NIhK)

500 years of architectural history in a flash

Medieval fortifications on the East Frisian peninsula have been the focus of NIhK research for several years. The oldest house in Leer, the Harderwykenburg, has now been documented as the basis for an analysis of the building history. The building probably was built after the middle of the 15th century by the Leer chieftain Hajo Unken. It has been owned by the von Knyphausen family for around 200 years, who are committed to restoring and researching the property in accordance with monument regulations. The three-storey tower house is one of the best-preserved examples of this type of building in northern Germany. Despite some alterations around 1600 done by the clerk of Leerort Diederich Harderwyk, numerous medieval architectural details such as slit-shaped windows have been preserved.

Two drones were used to take high-resolution photos of the building from different perspectives to document the structural details. A 3D model was then calculated in a second step using the "structure-from-motion" method. This model forms the basis for a subsequent architectural history analysis. The new technology allows the creation of deformation-appropriate views of the walls, which previously could only be drawn on paper with a pencil using scaffolding.