The Aerovue maps by Otto Betschmann
Cartographica Helvetica 38 (2008) 13–20
Otto Betschmann (1884–1959), a painter and graphic artist, produced a series of bird's-eye-views called Aerovue maps in the 1920s and 1930s. His Aerovue maps used an oblique parallel projection that combined a normal orthogonal map projection with three-dimensional topographic features shown in a side view. Betschmann's construction method which the Conzett & Huber publishing house used to produce a map series at the scale of 1:50,000 were protected with patents. To further simplify map construction, the Coradi Company of Zurich developed a modified pantograph to project contour lines. The Aerovue maps are notable for their innovative projection, large printed size, unusually vivid and natural colors, and a southern orientation that allowed for natural illumination from the south.