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When each cell of a grid is subject to a recursive partition, resulting in a "series of discrete global grids with progressively finer resolution", [2] forming a hierarchical grid, it is called a hierarchical DGG (sometimes "global hierarchical tessellation" [3] or "DGG system"). Discrete global grids are used as the geometric basis for the ...
Such a grid does not have a straightforward relationship to latitude and longitude, but conforms to many of the main criteria for a statistically valid discrete global grid. [9] Primarily, the cells' area and shape are generally similar, especially near the poles where many other spatial grids have singularities or heavy distortion.
A wide variety of such grids have been proposed or are currently in use, including grids based on "square" or "rectangular" cells, triangular grids or meshes, hexagonal grids, and grids based on diamond-shaped cells. A "global grid" is a kind of grid that covers the entire surface of the globe.
Snyder equal-area projection is a polyhedral map projection used in the ISEA (Icosahedral Snyder Equal Area) discrete global grids. It is named for John P. Snyder, who developed the projection in the 1990s. [1] It is a modified Lambert azimuthal equal-area projection, most often applied to a polyhedral globe consisting of an icosahedron. [2] [3]
Tessellation refer to a finite number of objects/cells that cover the surface as discrete partitions while Lattice refer to ordered sets of points that cover the surface in continuous vector space. The mathematical frame for a digital Earth reference model is a tessellation while the mathematical frame for an analog Earth reference is a lattice.
There are standard ways to build a grid covering the entire globe with cells of equal area, regular shape and other properties: Discrete Global Grid System (DGGS) is a series of discrete global grids satisfying all standardized requirements defined in 2017 by the OGC. [8]
Development of the quadrilateralized spherical cube projection on an Earth model [1] In mapmaking, a quadrilateralized spherical cube, or quad sphere for short, is an equal-area polyhedral map projection and discrete global grid scheme for data collected on a spherical surface (either that of the Earth or the celestial sphere).
C-squares (acronym for the Concise Spatial QUery And REpresentation System) is a system of spatially unique, location-based identifiers for areas on the surface of the earth, represented as cells from a latitude- and longitude-based Discrete Global Grid at a hierarchical set of resolution steps, obtained by progressively subdividing 10×10 degree World Meteorological Organization squares; the ...