Questions related to Discrete Global Grid Systems (DGGS)

A Discrete Global Grid (DGG) is a space-partioning mosaic data structure that instead of discretising the planar surface generated by a cartographic projection, discretises directly the Earth's surface. Thus they are also called geodetic grids.

A DGG is often obtained by projecting the Earth surface into a polyhedron, then dividing each of the polyhedron's face with a regular tesselation and then inverse projecting the tesselation back into the Earth's surface. Being the regular polyhedron with the largest number of faces, the Icosahedron is the predilect for this purpose.

A Discrete Global Grid System is a hierarchical set of DGG of increasing spatial resolution defined on the same polyhedron. For more details visit

Research on DGGS dates back to the 1980s, at the initiative of the Environment Protection Agency (EPA) of US. In 1992, the introduction of John Snyder's equal-area projection based on the icoashedron provided an important theoretical step forward. Research conducted by Kevin Sahr at the University of Oregon lead to the first DGGS open source software and further theoretical developments.

DGGS software:

  • DGGRID: C library developed by Kevin Sahr.

  • dggridR: R package wrapping DGGRID developed by Richard Barnes.

  • H3: C library developed by UBER.