Geocart Projections

What is a projection?

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conformal world in an ellipse

Parameters: Modular angle 0° << ß << 90°

Classification

Geocart menu class: Miscellaneous
Conformal

Graticule

Meridians: Central meridian is straight. Other meridians are complex curves.
Parallels: Equator is straight. Other parallels are complex curves.
Poles: Points
Symmetry: About the central meridian and the Equator

Scale

Increases rapidly with distance from the center

Distortion

Great distortion of area near the poles and the 180th meridians. Conformality fails at the poles.

Other features

The shape of the bounding ellipse can be varied. Lee uses an axial ratio of about 1.97 to 1 for convenience in using tabular values.

Usage

Novel whole-world maps

Origin

Presented by Oscar Sherman Adams (1874–1962) of the U.S. Coast and Geodetic Survey in 1925. Corrected by Andre Gougenheim in 1950 and Laurence Patrick Lee (1913-1985) of New Zealand in 1965.

Limiting form

As the modular angle that controls the shape of the ellipse approaches 90°, the map increasingly resembles the Lagrange circular projection.

Similar projections

See note under Adams projection of the world in a square I.

Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.