National Center for Geographic Information and Analysis

Hierarchical spatial data structures offer distinct advantages of data compression and fast access, but are difficult to adapt to the globe. Following Dutton (1984, 1988a, 1988b), we propose to project the globe onto an octahedron, and then to recursively subdivide each of its eight triangular faces into four triangles. We provide procedures for addressing the hierarchy, and for computingaddresses in the hierarchical structure from latitude and longitude, and vice versa. At any level in the hierarchy the finite elements are all triangles, but are only approximately equal in area and shape; we provide methods for computing area, and for finding the addresses of neighboring triangles