Research On The General Data Model Data Of Field Data For Spheroidal Discrete Grid

The global discrete grid system uses a specific method to recursively divide the earth's surface,forming a seamless,uniform and nested multi-resolution grid hierarchy,which provides a reliable theoretical basis for the unified description and expression of complex and diverse geographical phenomena.According to the dimensions,the global discrete grid is divided into spherical discrete grid and spheroidal discrete grid.The research of spherical discrete grid stays on the earth's surface and only supports the research of spatial data expression and mode calculation on the earth's surface.In fact,the entities and phenomena in the atmosphere,ionosphere,lithosphere and other space inside and outside the earth's surface also need to be organized,managed,expressed and visualized.Therefore,the research on the spheroidal discrete grid came into being.It is a three-dimensional global discrete grid,which can make up for the deficiency of the spherical grid in the space research of the earth system.However,the emergence of various spheroidal discrete grids has resulted in the mutual isolation of data between different grids.Therefore,a general data model is needed to support the exchange and application of field data in different spheroidal discrete grid,and to improve the ability of sharing,analysis and visualization of field data among different spheroidal discrete grids.This paper analyzes the components of the spheroidal discrete grid field data and describes the composition of the spheroidal discrete grid in detail.Based on the paging theory,this paper summarizes the paging mode of the field data in the spheroidal discrete grid,designs the general data model of the field data based on the spheroidal discrete grid,and realizes the storage and management of the grid field data in the database by using the pyramidal data organization mode.Then a prototype system is formed by designing grid data transmission service and visualization method,which verifies the ability of the general data model to express data of different grid fields.The research contents and achievements of this paper include:(1)construction of conceptual model of data of the spheroidal discrete gridAnalyze the components of the net field data.One of its components,the description of the ball-frame framework,is based on the definition of the grid systemdata model created by the open geospatial alliance(OGC),supplemented and improved to extend the framework of the spheroidal discrete grid.Then the grid field data is divided into pages.The paging field data is another component of the grid field data.Finally,the conceptual model of the grid field data is constructed together with the grid field data metadata.(2)data model and data organization are used for the spheroidal discrete gridOn the basis of the conceptual model of the spheroidal discrete grid field data,the conceptual model of the spheroidal discrete grid field data is summarized.The conceptual model is further abstracted into logical model and physical model.The pagination is used as pyramid block,the pyramid nesting model is used to organize the spheroidal discrete grid field data,the pyramid block is encoded by the filling curve,the storage and management of pyramid nested data is realized in the document database,in order to adapt to the efficient progressive data transmission and grid data visualization.(3)grid field data scheduling service and visualizationAccording to the data organization mode designed above,the service interface is designed to realize the scheduling of pyramid-shaped grid field data in the database.Then the visual cone clipping method is used to obtain the grid field data of corresponding scale according to the actual demand of the client to realize the progressive data transmission service.Then,Web GL technology is used to render grid tiles in different stages.The experimental results show that the proposed data model based on grid paging field data supports the expression of field data in the network,overcomes the limitation of different grid systems being independent from each other,and is an extension of the existing grid data model.For the storage of massive grid field data,the pyramid nested storage of grid paging field data is realized in the document database,and the grid field data transmission service is designed.The grid field data visualization using Web GL technology shows that this page-based pyramid nesting organization and service method has high concurrency efficiency,and the service-oriented prototype system architecture provides a new idea for the development of global discrete grid applications.