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A discrete global grid (DGG) is a mosaic that covers the entire Earth's surface. Mathematically it is a space partitioning : it consists of a set of non-empty regions that form a partition of the Earth's surface. [ 1 ]
Triangulated irregular network TIN overlaid with contour lines. In computer graphics, a triangulated irregular network (TIN) [1] is a representation of a continuous surface consisting entirely of triangular facets (a triangle mesh), used mainly as Discrete Global Grid in primary elevation modeling.
Criteria for optimal discrete global gridding have been proposed by both Goodchild and Kimerling [2] in which equal area cells are deemed of prime importance. Quadtrees are a specialised form of grid in which the resolution of the grid is varied according to the nature and complexity of the data to be fitted, across the 2-d space.
The team proposed a complete area location coding system called "1+4 basic code, N serial extended codes". [3] Above these codes, the global subdivision grid code is a basic one and it has been completed. GNGC is part of research on Global Sub-division Grid (GSG, or global discrete grid, geographic grid or spatial information grid).
In the context of Cartography and GIS - Geographic Information System, is common to identify cells of the partition by standard codes. For example the for HUC code identifying hydrographical basins and sub-basins, ISO 3166-2 codes identifying countries and its subdivisions, or arbitrary DGGs - discrete global grids identifying quadrants or ...
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 "global DEM" refers to a discrete global grid. DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally produced relief maps. A digital terrain model (DTM) represents specifically the ground surface while DEM and DSM may represent tree top canopy or building roofs.
The Snake Projection algorithm converts between geographical and grid coordinates, however the method of technical implementation can vary. One method of implementing a Snake Projection is to define using an NTv2 geodetic transformation coupled with a standard parameterised map projection (such as Transverse Mercator ); this is increasing in ...