关键词: 地球剖分网格, 球体测地线八叉树网格, 真三维, 地质体, 郑州航空港经济区

Abstract:

Three-dimensional (3D) modeling has always been the subject of research in earth information science. The 3D geological space expression can accurately reveal the spatial structure and distribution pattern of geological phenomena and processes. Under the background of spatiotemporal big data, the contemporary Digital Earth platform is facing new opportunities. The traditional 3D geological modeling methods have the following limitations: local small area, projection data, surface static modeling, difficult 3D spatial query and analysis, and unfavorable organization and management of spatiotemporal big data. The Earth Tessellation Grid provides a new solution to solving the above problems and building a new generation digital earth platform with its global omnidirectional perspective, cyclic recursive splitting mechanism, and organic flexible codec strategy. Taking the Zhengzhou Airport Economic Zone as an example, this paper established a regional true 3D geological model framework based on the Sphere Geodesic Octree Grid bricks (SGOG grids) and conducted spatial analysis using measured geological data. Firstly, the original data was preprocessed. It mainly included data reading, data encryption, and projection and coordinate transformation. Next, the geological data and the SGOG split data was matched. The true 3D geological framework was constructed by matching the brick nodes of SGOG specific splitting level with the geological envelope feature points. Then, the multi-scale and multi-story 3D models were established through vulnerability patching and shade rendering. Among them, the vulnerability filling was achieved by recombining the SGOG brick voxels by their coding logic, and the shaded rendering of the bricks was implemented by the OSG's rendering engine. Finally, based on the above, the spatial analysis of the true 3D geological model was conducted, including the true 3D profile analysis, digital drilling, and geometric feature parameter calculation. The profiles were established by judging the position of the brick relative to the section line, which included three types of warp, weft, and arbitrary lines. Digital drillings were constructed by determining the bricks where the center point of the drillings were located. By calculating the external surface area of the upper and lower bricks of the geological body model and the volume of all the bricks, the upper and lower surface area and volume were determined. The experimental results show that the modeling method proposed in this paper is not only simple in structure and easy to operate, but also suitable for complex and irregular geological bodies. It can flexibly express the precision and scale by using the multi-scale characteristics of SGOG bricks, and convenient for multi-angle true 3D spatial analysis. The earth tessellation grid is an inevitable trend in the development of the digital earth.

Key words: Earth Tessellation Grid, Sphere Geodesic Octree Grid (SGOG), true three-dimensional, geological body, Zhengzhou airport economic zone