Cahill–Keyes projection

The projection was designed to achieve a number of desirable characteristics, namely symmetry of component maps (octants), scalability allowing the map to continue to work well even at high resolution, uniformity of geocells, metric-based joining edges, minimized distortion compared to a globe, and an easily understood orientation to enhance general usability and teachability.

[1][2][3] The Cahill–Keyes projection was designed with four fundamental considerations in mind: visual fidelity to a globe, proportional geocells, 10,000 km lengths for each of its octants' three main joined edges, and an M-shape Master-Map profile.

The resulting map comprises 8 octants.

Each octant is an equilateral triangle with three segments per side.

The specific process for constructing the graticule divides each half-octant into twelve zones, each of which has different formulae for coordinate calculations.