A digital Earth system based upon a hexagonal subdivision of a polyhedron representation of the Earth utilizes a computer-implemented method for assigning identifiers. The method comprises defining a tessellation of hexagonal cells, the tessellation having a first axis and a second axis, the first axis being perpendicular to a first side of the hexagonal cells, the second axis being 120 degrees from the first axis and being perpendicular to a second side of the hexagonal cells; selecting an origin cell for the tessellation and assigning a unique identifier comprising a first value and a second value thereto; and assigning a unique identifier to each cell other than the origin cell, the unique identifier for each of these cells comprising a first vector value and a second value, the first vector value and the second vector value being indicative of the location of the cell to the origin cell along the first and second axis respectively.