Research On Earth Sphere Shell Space Grid Theory And Algorithms

The range of human spatial activities have been promoted to various levels of space such asland, sea, air, sky, while spatial observation scope has been enlarged to every sphere shell ofearth systems, and spatial exploration ability be enhanced. More and more scientific researchand military and economic activities have shown itself such characteristics as globalthree-dimensional distribution, multi-spatial level, multi-temporal and spatial scale, crossspecialties, so that these are depended on the construction of global uniform space frameworkand integration of earth sphere shells information. Therefore, the construction of sphere shellspace grid and the establishment of uniform space framework of land, sea, air, sky becomes animportant problem.The followings are what we have done in this dissertation:1. The comprehensive review of current achievements has been taken firstly, and theseproblems in existing space grid models have been pointed out. Then, the sphere shell space gridis the new direction of geographic space grid has been brought forward, which is following thedevelopment of geographic space grid from plan grid to solid grid, from spherical surface tosphere interior.2. The Sphere Shell Space Grid is putted forward for the first time. The basic conception ofSphere Shell Space and Sphere Shell Space Grid are proposed, and then their connotations andtheoretical characteristics have been discussed in details. The basic idea of subdivision of SphereShell Space Grid is that, the earth spherical surface is set as starting surface; earth has beendivided into several homocentric datum sphere shells along the radial direction, and then the gridsubdivision of each datum sphere shell has been taken place. And Sphere Shell Space Grid iscomared with Sphere Degenerated Octree Grid and Earth System Spheres. At last, there are6ratiocinations concluded from theoretical analysis. This provides a primary guide for theconstruction of Sphere Shell Space Grid.3. The extended-Octree (e-Octree) subdivision model of Sphere Shell Space Grid isproposed. The design idea and three subdivision mechanisms including regular subdivision,degraded subdivision and adaptive subdivision are presented first. The mathematical form ofpartition curve, partition surface and partition voxel are given out. And then the equal areaproperty of sphere shell surface grid generated by the partition curve has been proved usingdifferential geometry. The e-Octree grid coding model is proposed according to three subdivisionmechanisms, and also the algorithm of conversion between grid code and geographic coordinate.Experiments have shown that e-Octree subdivision and code model has improved the agile ability while holding coherence. This is favorable for spatial entity representation and spatialinformation organization.4. The COG model and PNM model used for volume object representation and topologicalrelation description is proposed. Firstly, the topological continuity of discrete representation ofvolume object is analyzed based on digital topology, and then the continuous octree grid (COG)concept is given out, and COG generation algorithm is presented up. Secondly, the topologicalrelationship description problem between two volume objects has been addressed on. Theformalization of point neighborhood concept and its configuration types are defined. The3Dtopological relationship is coded based on point neighborhood configuration. Typical examplesanalysis has shown that more kinds of topological relationships have been classified by PNMthan9IM.5. The storage and access mechanism based on space filling curve (SFC) for Sphere ShellSpace Grid is brought forward. Firstly, the SFC clustering number model is putted forward, andthen the conclusion that continuous SFCs is more efficiency than un-continuous SFCs is provedtheoretically. Secondly, the Hilbert SFC is chosen for spatial data index construction, and theregular octree grid Hilbert index is presented. But it is not sufficient for multi-source,multi-resolution data storage and access, so the compact Hilbert index is presented, which isbased on Gray Code ordering algorithm. The construction of compact Hilbert index is given indetails. Experiments have shown that compact Hilbert index is better than standard Hilbert indexin storage and query evidently.