Common Icosahedral DGG Orientation Approaches

Any geospatial frame of reference must be fixed relative to the surface of the earth. The links below illustrate three common approaches to orienting DGGs based on the spherical icosahedron:

Vertices at Poles Orientation

The most commonly proposed base icosahedron orientation is to place an icosahedron vertex at the north and south poles and to orient the icosahedron so an edge extends from the north pole down the prime meridian at 00 longitude.

Four views of this placement are given below:

Standard ISEA Orientation

The standard orientation of ISEA DGGs is specified by placing one icosahedron vertex at 11.250E longitude, 58.282525590N latitude, and placing an adjacent vertex at an azimuth of 0.00 from the first vertex. Note that this placement is symmetrical about the equator and has a single icosahedron vertex falling on land.

Four views of this placement are given below:

R. Buckminster Fuller’s Dymaxion Orientation

The Dymaxion orientation of R. Buckminster Fuller can be specified by placing one icosahedron vertex at 5.245390W longitude, 2.3008820N latitude, and placing an adjacent vertex at an azimuth of 7.466580 from the first vertex. Note that this placement is the only known icosahedron placement with no icosahedron vertices falling on land.

Four views of this placement are given below: