Abstract
Discrete global grid systems (DGGSs) are an emerging multiresolution 3D model used to integrate and analyze big earth data. The characteristic of multiresolution is usually realized by hierarchically subdividing cells on the sphere using certain refinement. This paper introduces mixed aperture three- and four- icosahedral hexagonal DGGSs using two types of refinement, the various combinations of which can provide more resolutions compared with pure aperture hexagonal DGGSs and can flexibly design the aperture sequence according to the target resolutions. A general hierarchy-based indexing method is first designed, and related indexing arithmetics and algorithm are developed based on the indexing method. Then, the grid structure on the surface of the icosahedron is described and by projection spherical grids are obtained. Experiments show that the proposed scheme is superior to pure aperture schemes in choosing grid resolutions and can reduce the data volume by 38.5% in representing 1-km resolution raster dataset; using the proposed indexing arithmetics to replace spherical geometry operations in generating discrete spherical vector lines based on hexagonal cells can improve the generation efficiency.
Highlights
In recent years, the explosive growth of geospatial data volume and the increasingly complicated and multiple data structures have posed a great challenge to their integration and analysis [1]
Discrete global grid systems (DGGSs) differ in basic elements such as the base polyhedron, the type of cells, the type of refinement and the indexing method
This paper focuses on mixed aperture 3 and 4 hexagonal DGGSs and proposes a hierarchy-based indexing method based on cell directions
Summary
The explosive growth of geospatial data volume and the increasingly complicated and multiple data structures have posed a great challenge to their integration and analysis [1]. (2) GTOPO30 data resampling based on the proposed scheme; After determining the grid level, we resample the GTOPO30 dataset into it This experiment uses the indirect resampling method where the calculation is from each index of generated hexagonal grids to the pixel of the original DEM to avoid irregular situations. Our research group has proposed one algorithm to solve the above problems, called “duality and dimensionality reduction discrete line generation algorithm” [35] In this algorithm, the index arithmetics of hexagonal grids is used to replace spherical geometry operation of coordinates of cells in generating the discrete vector line. The index arithmetics of hexagonal grids is used to replace spherical geometry operation of coordinates of cells in generating the discrete vector line When calculating the distance condition, the algorithm needs to use the inverse Snyder polyhedral projection to convert the cell indices into geographical coordinates, but the inverse Snyder projection requires iterative root finding approaches, which limits the improvement of our algorithm
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