| The Discrete Global Grid System is an organic grid system that recursively dissects the Earth's surface according to certain rules.With reliable theoretical foundation support and strict scale transformation relationship,it is an effective space-time big data organization and management framework to construct the Digital Earth.At present,some famous domestic & abroad experts and scholars have put forward more than 20 kinds of schemes to effectively solve the problem of scale and projection deformation.It has been widely applied in the fields of global spatial data hierarchy subdivision and index,global meteorological and hydrological simulation,spatial data quality and cartographic synthesis,global massive spatial data management,global visual models and so on.However,there is still a serious problem of "information island" in the existing Discrete Global Grid System,such as self-contained,closed and lack of connectivity.Therefore,it is of great significance to study the connectivity and interoperability among multi-type Discrete Global Grid System.Based on the ontology cognition of grid model,this study analyzes the structural elements of the Discrete Global Grid System.Take the spherical quaternion triangle network as an example,it is an interoperation mechanism from two perspectives of coding conversion and integrated coding to study coding and multi-type grids.According to revealing the unified characteristics between grid coding and structural elements,it provides basic theory and coding transform for the grid integration support,namely Quaternary Triangular Mesh code conversion method,mesh,correlation analysis,Discrete Global Grid System integration encoding structure factors and generation method.It has obtained the good effect by using rainfall and surface elevation data for example,which provides a new theoretical and technical reference for the construction of the Digital Earth platform.The main work and contributions of this paper are as follows:1.Design and implement the conversion algorithm among various coding types of Quaternary Triangular Mesh.With the subdivision rule of Quaternary Triangular Mesh,it is proposed through the sorting mode of coding in the same hierarchy by the directivity characteristics of hierarchical coding,basing on the classification and analysis of various coding schemes,A general mapping rule for spherical quaternion triangle coding,namely resampling transformation method,is proposed in view of the fact that all kinds of coding schemes contain the same geographical coordinates.Aiming at the common hierarchical coding,a hierarchical transformation method is proposed.For other codes,such as triangle grid code based on linear quadtree rhombus grid,the mapping rules of row and column transformation are constructed.Finally,it makes comparision between the above three algorithms.According to the experimental results,the hierarchical transformation algorithm and the column transformation algorithm are more efficient.2.An adaptive generation method of multiple discrete grids driven by grid integrative coding is proposed.Based on the analysis of the unified characteristics of three kinds of Discrete Global Grid System(triangle,quadrilateral,hexagon)in terms of the dialectical relationship between the critical point and the grid element,the distribution law of the grid points is revealed.Taking the spherical quaternion triangulation as an example,the arithmetic of difference circle layer coding and decoding of lattice points is designed and implemented.According to the spatial geometry relations of three kinds of grids,an adaptive multi-grid generation method based on integrated grid coding is proposed.The correctness and feasibility of the DEM multi-grid representation in Henan province are verified as an example,which provides a new idea for the interoperation mechanism of Discrete Global Grid System.3.Experimental system development.Based on the above research,an object-oriented multi-discrete grid data structure is designed,which realizes a multi-discrete grid interoperating system based on standard C++ language,development platform Visual Studio 2017,Qt,3D rendering engine OSG and database My SQL.It mainly consists of two basic modules: the spherical quaternary triangulation network coding conversion and the multi-discrete grid construction... |
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