关键词: 数字地球, 全球离散网格, 全球空间网格, 球体大圆弧QTM八叉树网格, 可视化

Abstract:

3D visualization is a key supporting technology of modern geographic information science. The spherical surface subdivision bricks were employed to build 2.5D static digital earth surface in the first generation of Digital Earth platforms represented by Google Earth. These platforms implemented earth surface data integration, model developments and applications, but did not involve the spaces above the surface and subsurface spaces. Therefore, the study of true 3D visualization technology based on spherical solid subdivision bricks is essential and necessary. The subdivision rules of Sphere Geodesic QTM Octree Grid, the geometric features, and the coding principle of brick system were described in this research. The transition algorithm between a brick code and its 3D Cartesian coordinate were designed and conducted. A prototype framework of true 3D digital earth visualization platform under C++ and OSG language environment was developed to achieve the arbitrary subdivision of a sphere, the visual modeling of underground, the surface and aerial entities, and the simple 3D spatial analysis. The advantages and prospect of the new generation Digital Earth platform in integration, management, model development and application of integrated space-ground spatial big data were demonstrated. The results indicate that the Sphere Geodesic Octree Grid has advantages such as simplicity, regularity, clear geometric features, being suitable as a global discrete space datum, and being conducive to the spatial entity modeling and visualization, etc. It can be used as the basis of data model to develop a new generation of Digital Earth platform.

Key words: Digital Earth, Discrete Global Grids (DGGs), Earth System Spatial Grid (ESSG), Sphere Geodesic Octree Grid (SGOG), visualization