Sphere Shell Space 3D Grid
The global spatial grid is an important spatial data model for Digital Earth. Discrete Global Grid provides a means of rasterizing the earth surface, and then has been considered as the basic data model for digital globes. But Discrete Global Grid is only confined to the surface, because it can not reach to the earth inside and outside. The Sphere Shell Space 3D Grid (SSSG) proposed here provides a new spatial reference framework for the whole earth 3D space for Digital Earth. The basic conceptions and requirements of SSSG have been discussed in details. It is designed to represent spatial objects distributed from underground, land, sea, air to space within a uniform framework, and also to uniformly organize various kinds of spatial information in each earth sphere shells.