Spatial subdivision and coding of a global three-dimensional grid: Spheoid Degenerated-Octree Grid

Map projections had brought a lot of problems to regional and global spatial data organization and representation, such as distortion, geometric fissure and space metric error. Fortunately, Discrete Global Grid (DGG) gave a feasible solution, but it was only confined to the Earth surface, not reached to the Earth inside and outside, which was also very important to human activity. In this paper, a global three-dimensional (3D) grid, called as Spheoid Degenerated Octree Grid (SDOG), was presented, and two kinds of coding methods for SDOG, called as SDZ and MDZ, were proposed. The properties of SDOG were discussed and the performance of SDZ and MDZ was compared with QuaPA experimentally. It revealed that SDOG is a 3D grid with properties of global continuity, multi-hierarchy, similar shape and approximate size, and can serve well for global spatial data organizing and representing; SDZ and MDZ are high performance coding methods, and MDZ is a nicer choice for SDOG coding.