Directory of Map Projections

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Gilbert two-world perspective


A compromise projection that portrays most of the world within a circle, evoking a globe view without restricting the view of the far side. A slight crescent of the globe is not visible.




Meridians: Complex curves.
Parallels: Complex curves.


The map is undistorted at 5°N on the central meridian. Much of the map is dominated by areal inflation, but the central region has low distortion, and the outer, low latitudes are balanced between areal inflation and angular deformation. The map has an unusual X-shaped pattern of high angular deformation. The outer meridians are effectively not visible even if present due to extreme compression.


Edgar N. Gilbert devised a globe before 1975 with two copies of the world on it, each filling one hemisphere. He kept it in his office as a “visual illusion” that most visitors did not recognize anything odd about. Alan A. DeLucia and John P. Snyder reconstructed the method mathematically and published it in 1986.

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