Chapter 19. Hierarchical Triangular Mesh
Most of us are used to locating positions on earth with (longitude, latitude) pairs. But this traditional system has problems as you get closer to either the North or South Pole and the math involved uses spherical trigonometry.
An alternative system is the Hierarchical Triangular Mesh, or HTM for short. While (longitude, latitude) pairs are based on establishing a point in a two-dimensional coordinate system on the surface of the earth, HTM is based on dividing the surface into almost-equal sized triangles with a unique identifier to locate something by a containing polygon.
If you have seen a geodesic dome or Buckminster Fuller’s maps, you have some feeling for this approach. HTM start with an octahedron ...
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