Discrete Global Grid

A Discrete Global Grid (DGG) consists of a set of regions that form a partition of the Earth’s surface, where each region has associated with it a single point contained in that region. A Discrete Global Grid System (DGGS) is a series of discrete global grids, usually consisting of increasingly finer resolution grids.

Discrete Global Grids are used as the geometric basis for the creation of geospatial data structures. Each region/point combination in the grid is a called a "cell," and depending on the application, data objects or values may be associated with the cells themselves, or with either the cell regions or cell points. DGGs have been proposed for use in a wide range of geospatial applications, including vector and raster location representation, data fusion, and spatial databases.

The most common class of Discrete Global Grids are those that place cell center points on longitude/latitude meridians and parallels, or which use the longitude/latitude meridians and parallels to form the boundaries of rectangular cells. Examples of such grids include:

Arakawa grids are used for Earth system models for meteorology and oceanography. For example, the Global Environmental Multiscale Model (GEM) uses Arakawa grids for global climate modeling.

Many Digital Elevation Models are created on a grid of points placed at a regular angular increments of latitude and longitude. Examples include the Global 30 Arc-Second Elevation Dataset (GTOPO30). and the Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)

World Grid Squares are a compatible extension of Japanese Grid Squares standarized in Japan Industrial Standards (JIS X0410) to worldwide. The World Grid Square code can identify grid squares covering the world based on 6 layers. We can express a grid square by using from 6 to 13 digit sequence with accordance to its resolution.

A Geodesic Discrete Global Grid System (sometimes called simply a geodesic grid) is formed by recursively sub-dividing a planar or spherical polyhedra. Examples of such grids include:

ISEA Discrete Global Grids are a class of grids proposed by researchers at Oregon State University. The grid cells are created as regular polygons on the surface of an icosahedron, and then inversely projected using the Icosahedral Snyder Equal Area (ISEA) map projection to form equal area cells on the sphere. Cells may be hexagons, triangles, or quadrilaterals. Multiple resolutions are indicated by choosing an aperture, or ratio between cell areas at consecutive resolutions. Some applications of ISEA DGGs include data products generated by the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite, which uses an ISEA4H9 (aperture 4 Hexagonal DGGS resolution 9), and the commercial software WorldView, which uses an ISEA3H (aperture 3 Hexagonal DGGS).

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