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World Meteorological Organization Squares
World Meteorological Organization (WMO) squares is a system of geocodes that divides a world map with latitude-longitude gridlines into grid cells of 10° latitude by 10° longitude, each with a unique, 4-digit numeric identifier (refer chart at NODWorld Ocean Database 2005page). On the plate carrée projection, the grid cells appear square; however, if the Mercator projection is used, the grid cells appear 'stretched' vertically nearer the tops and bottoms of the map. On the actual surface of the Globe, the cells are approximately "square" only adjacent to the Equator, and become progressively narrower and tapered (also with curved northern and southern boundaries) as they approach the poles, and cells adjoining the poles are unique in possessing three faces rather than four. Each 10°x10° square is allocated a number between 1000 and 7817. The numbering system is based first on "global quadrant" numbers where 1=NE, 3=SE, 5=SW, 7=NW which gives the initial digit of any square ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geocode
A geocode is a code that represents a geographic entity (location or object). It is a unique identifier of the entity, to distinguish it from others in a finite set of geographic entities. In general the ''geocode'' is a human-readable and short identifier. Typical geocodes and entities represented by it: * ''Country code'' and subdivision code. Polygon of the administrative boundaries of a country or a subdivision. The main examples are ISO codes: ISO 3166-1 alpha-2 code (e.g. AF for Afghanistan or BR for Brazil), and its subdivision conventions, such as subdivision codes (e.g. AF-GHO for Ghor province) or subdivision codes (e.g. BR-AM for Amazonas state). * ''DGG cell ID''. Identifier of a cell of a discrete global grid: a Geohash code (e.g. ~0.023 km2 cell 6vjyngd at the Brazilian's center) or an OLC code (e.g. ~0.004 km2 cell 58PJ642P+4 at the same point). * ''Postal code''. Polygon of a postal area: a CEP code (e.g. 70040 represents a Brazilian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsden Square
Marsden square mapping or Marsden squares is a system that divides a world map with latitude-longitude gridlines (e.g. plate carrée projection, Mercator or other) between 80°N and 70°S latitudes (or 90°N and 80°S: refer chart at Ocean Teacher’Ocean Geographypage) into grid cells of 10° latitude by 10° longitude, each with a geocode, a unique numeric identifier. The method was devised by William Marsden (b. 1754, d. 1836), when first secretary of the British Admiralty, for collecting and combining geographically-based information about the oceans. Structure and design On the plate carrée projection the grid cells appear square, although if the Mercator projection is used, the grid cells appear "stretched" vertically nearer the tops and bottoms of the map. On the actual surface of the globe, the cells are approximately "square" only adjacent to the equator, and become progressively narrower and tapered (also with curved northern and southern boundaries) as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QDGC
QDGC - Quarter Degree Grid Cells (or QDS - Quarter degree Squares) are a way of dividing the longitude latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ... degree square cells into smaller squares, forming in effect a system of geocodes. Historically QDGC has been used in a lot of African atlases. Several African biodiversity projects uses QDGC, among which The atlas of Southern African Birds is the most prominent one. In 2009 a paper by Larsen ''et al.'' describes the QDGC standard in detail. Mechanics The squares themselves are based on the degree squares covering earth. QDGC represents a way of making approximately equal area squares covering a specific area to represent specific qualities of the area covered. However, differences in area between 'squares' enlarge along ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-squares
C-squares (acronym for the ''Concise Spatial QUery And REpresentation System'') is a system of spatially unique, location-based identifiers (geocodes) 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 term "c-square" is also available for use to designate any component cell of the grid. Individual cell identifiers incorporate literal values of latitude and longitude in an interleaved notation (producing grid resolutions of 10, 1, 0.1 degrees, etc.), together with additional digits that support intermediate grid resolutions of 5, 0.5, 0.05 degrees, etc. The system was initially designed to represent data "footprints" or spatial extents in a more flexible manner than a standard minimum bounding rectangle, and to support "lightweight", text-based spatial querying; it can al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsden Square
Marsden square mapping or Marsden squares is a system that divides a world map with latitude-longitude gridlines (e.g. plate carrée projection, Mercator or other) between 80°N and 70°S latitudes (or 90°N and 80°S: refer chart at Ocean Teacher’Ocean Geographypage) into grid cells of 10° latitude by 10° longitude, each with a geocode, a unique numeric identifier. The method was devised by William Marsden (b. 1754, d. 1836), when first secretary of the British Admiralty, for collecting and combining geographically-based information about the oceans. Structure and design On the plate carrée projection the grid cells appear square, although if the Mercator projection is used, the grid cells appear "stretched" vertically nearer the tops and bottoms of the map. On the actual surface of the globe, the cells are approximately "square" only adjacent to the equator, and become progressively narrower and tapered (also with curved northern and southern boundaries) as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grid (spatial Index)
In the context of a spatial index, a grid or mesh is a regular tessellation of a manifold or 2-D surface that divides it into a series of contiguous cells, which can then be assigned unique identifiers and used for spatial indexing purposes. 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. Types of grids Square or rectangular grids are frequently used for purposes such as translating spatial information expressed in Cartesian coordinates (latitude and longitude) into and out of the grid system. Such grids may or may not be aligned with the grid lines of latitude and longitude; for example, Marsden Squares, World Meteorological Organization squares, c-squares and others are aligned, while Universal Transverse Mercator coordinate sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geocode
A geocode is a code that represents a geographic entity (location or object). It is a unique identifier of the entity, to distinguish it from others in a finite set of geographic entities. In general the ''geocode'' is a human-readable and short identifier. Typical geocodes and entities represented by it: * ''Country code'' and subdivision code. Polygon of the administrative boundaries of a country or a subdivision. The main examples are ISO codes: ISO 3166-1 alpha-2 code (e.g. AF for Afghanistan or BR for Brazil), and its subdivision conventions, such as subdivision codes (e.g. AF-GHO for Ghor province) or subdivision codes (e.g. BR-AM for Amazonas state). * ''DGG cell ID''. Identifier of a cell of a discrete global grid: a Geohash code (e.g. ~0.023 km2 cell 6vjyngd at the Brazilian's center) or an OLC code (e.g. ~0.004 km2 cell 58PJ642P+4 at the same point). * ''Postal code''. Polygon of a postal area: a CEP code (e.g. 70040 represents a Brazilian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatial Database
A spatial database is a general-purpose database (usually a relational database) that has been enhanced to include spatial data that represents objects defined in a geometric space, along with tools for querying and analyzing such data. Most spatial databases allow the representation of simple geometric objects such as points, lines and polygons. Some spatial databases handle more complex structures such as 3D objects, topological coverages, linear networks, and triangulated irregular networks (TINs). While typical databases have developed to manage various numeric and character types of data, such databases require additional functionality to process spatial data types efficiently, and developers have often added ''geometry'' or ''feature'' data types. The Open Geospatial Consortium (OGC) developed the Simple Features specification (first released in 1997) and sets standards for adding spatial functionality to database systems. The '' SQL/MM Spatial'' ISO/IEC standard is a pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
C-squares
C-squares (acronym for the ''Concise Spatial QUery And REpresentation System'') is a system of spatially unique, location-based identifiers (geocodes) 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 term "c-square" is also available for use to designate any component cell of the grid. Individual cell identifiers incorporate literal values of latitude and longitude in an interleaved notation (producing grid resolutions of 10, 1, 0.1 degrees, etc.), together with additional digits that support intermediate grid resolutions of 5, 0.5, 0.05 degrees, etc. The system was initially designed to represent data "footprints" or spatial extents in a more flexible manner than a standard minimum bounding rectangle, and to support "lightweight", text-based spatial querying; it can al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Date Line
The International Date Line (IDL) is an internationally accepted demarcation on the surface of Earth, running between the South and North Poles and serving as the boundary between one calendar day and the next. It passes through the Pacific Ocean, roughly following the 180° line of longitude and deviating to pass around some territories and island groups. Crossing the date line eastbound decreases the date by one day, while crossing the date line westbound increases the date. Geography Circumnavigating the globe People traveling westward around the world must set their clocks: *Back by one hour for every 15° of longitude crossed, and *Forward by 24 hours upon crossing the International Date Line. People traveling eastward must set their clocks: *Forward by one hour for every 15° of longitude crossed, and *Back by 24 hours upon crossing the International Date Line. Failing to do this would make their time inaccurate to the local time. The Arab geographer Abulfed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Map
A world map is a map of most or all of the surface of Earth. World maps, because of their scale, must deal with the problem of map projection, projection. Maps rendered in two dimensions by necessity distort the display of the three-dimensional surface of the earth. While this is true of any map, these distortions reach extremes in a world map. Many techniques have been developed to present world maps that address diverse technical and aesthetic goals. Charting a world map requires global knowledge of the earth, its oceans, and its continents. From prehistory through the Middle ages, creating an accurate world map would have been impossible because less than half of Earth's coastlines and only a small fraction of its continental interiors were known to any culture. With exploration that began during the European Renaissance, knowledge of the Earth's surface accumulated rapidly, such that most of the world's coastlines had been mapped, at least roughly, by the mid-1700s and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prime Meridian
A prime meridian is an arbitrary meridian (a line of longitude) in a geographic coordinate system at which longitude is defined to be 0°. Together, a prime meridian and its anti-meridian (the 180th meridian in a 360°-system) form a great circle. This great circle divides a spheroid, like the Earth, into two hemispheres: the Eastern Hemisphere and the Western Hemisphere (for an east-west notational system). For Earth's prime meridian, various conventions have been used or advocated in different regions throughout history. The Earth's current international standard prime meridian is the IERS Reference Meridian. It is derived, but differs slightly, from the Greenwich Meridian, the previous standard. A prime meridian for a planetary body not tidally locked (or at least not in synchronous rotation) is entirely arbitrary, unlike an equator, which is determined by the axis of rotation. However, for celestial objects that are tidally locked (more specifically, synchronous), th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_033.jpg "Click for more on -> Prime Meridian")