The Drei Karten-Klippen generalized the knowledge of the projection of the surface of the sphere on the map, the representation of the three-dimensional Earth's surface on the two-dimensional paper and the selection and generalization of the map objects, basic questions that made Sydow pioneering.
The Drei Karten-Klippen advanced the understanding of projecting a sphere's surface onto a map, representing the three-dimensional Earth's surface on two-dimensional paper, and selecting and generalizing map objects, fundamental questions that made Sydow trailblazing.