Adopting Uber H3 index

[danlooo]

The order in which cells are stored in memory determines the chunking and thus access speed of the data (read, query). Cells nearby in geographical space should also be nearby in memory space. See #28 for general thoughts on indexing schemes.

Uber H3 has a sophisticated cell index allowing fast access of parents (which is just a prefix of the address) and neighbors (All children of a parent aka all cells with same prefix). DGGRID ISEA7H is very similar to Uber H3 and will profit from a similar indexing scheme (Kmoch et al. 2022). Can we adopt Uber H3 indexing scheme to ISEA7H and otthers?

Feature	DGGRID ISEA7H	Uber H3
Cell topology	Hexagon and others	Hexagon
Cell Aperture	7 and others	7
Geoid	unit sphere	unit sphere
Polyhedron	Icosahedron	Icosahedron
Cell centering	Pentagon centered at polhydron vertex	Hexagon centered in polyhedron face center

Uber H3 base cells at one icosahedron face

ISEA7H Icosahedron

ISEA7H at resolution 0 (12 red pentagons) and resolution 1 (60 white hexagons + 12 white pentagons)