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The geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on the Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system, the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface.
A projected coordinate system – also called a projected coordinate reference system, planar coordinate system, or grid reference system – is a type of spatial reference system that represents locations on Earth using Cartesian coordinates (x, y) on a planar surface created by a particular map projection. Each projected coordinate system, such as "Universal Transverse Mercator WGS 84 Zone 26N," is defined by a choice of map projection (with specific parameters), a choice of geodetic datum to bind the coordinate system to real locations on the earth, an origin point, and a choice of unit of measure. Hundreds of projected coordinate systems have been specified for various purposes in various regions.
The Maidenhead Locator System is a geocode system used by amateur radio operators to succinctly describe their geographic coordinates, which replaced the deprecated QRA locator, which was limited to European contacts. Its purpose is to be concise, accurate, and robust in the face of interference and other adverse transmission conditions. The Maidenhead Locator System can describe locations anywhere in the world.
A geocode is a code that represents a geographic entity. 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.
The National Topographic System or NTS is the system used by Natural Resources Canada for providing general purpose topographic maps of the country. NTS maps are available in a variety of scales, the standard being 1:50,000 and 1:250,000 scales. The maps provide details on landforms and terrain, lakes and rivers, forested areas, administrative zones, populated areas, roads and railways, as well as other human-made features. These maps are currently used by all levels of government and industry for forest fire and flood control, depiction of crop areas, right-of-way, real estate planning, development of natural resources and highway planning. To add context, land area outside Canada is depicted on the 1:250,000 maps, but not on the 1:50,000 maps.
In geography, location or place are used to denote a region on Earth's surface. The term location generally implies a higher degree of certainty than place, the latter often indicating an entity with an ambiguous boundary, relying more on human or social attributes of place identity and sense of place than on geometry. A populated place is called a settlement.
The Universal Transverse Mercator (UTM) is a map projection system for assigning coordinates to locations on the surface of the Earth. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth surface as a perfect ellipsoid. However, it differs from global latitude/longitude in that it divides earth into 60 zones and projects each to the plane as a basis for its coordinates. Specifying a location means specifying the zone and the x, y coordinate in that plane. The projection from spheroid to a UTM zone is some parameterization of the transverse Mercator projection. The parameters vary by nation or region or mapping system.
Marsden square mapping or Marsden squares is a system that divides a world map with latitude-longitude gridlines between 80°N and 70°S latitudes into grid cells of 10° latitude by 10° longitude, each with a geocode, a unique numeric identifier. The method was devised by William Marsden, when first secretary of the British Admiralty, for collecting and combining geographically based information about the oceans.
The World Geographic Reference System (GEOREF) is a geocode, a grid-based method of specifying locations on the surface of the Earth. GEOREF is essentially based on the geographic system of latitude and longitude, but using a simpler and more flexible notation. GEOREF was used primarily in aeronautical charts for air navigation, particularly in military or inter-service applications, but it is rarely seen today. However, GEOREF can be used with any map or chart that has latitude and longitude printed on it.
The Global Area Reference System (GARS) is a standardized geospatial reference system developed by the National Geospatial-Intelligence Agency (NGA) for use across the United States Department of Defense. Under the Chairman of the Joint Chiefs of Staff Instruction CJCSI 3900.01C dated 30 June 2007, GARS was adopted for use by the US DoD as "the “area-centric” counterpart to the “point-centric” MGRS". It uses the WGS 1984 Datum and is based on lines of longitude (LONG) and latitude (LAT). It is intended to provide an integrated common frame of reference for joint force situational awareness to facilitate air-to-ground coordination, deconfliction, integration, and synchronization. This area reference system provides a common language between the components and simplifies communications. GARS is primarily designed as a battlespace management tool and not to be used for navigation or targeting.
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. 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 as they approach the poles, and cells adjoining the poles are unique in possessing three faces rather than four.
C-squares 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, together with additional digits that support intermediate grid resolutions of 5, 0.5, 0.05 degrees, etc.
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.
A geodesic grid is a spatial grid based on a geodesic polyhedron or Goldberg polyhedron.
Geohash is a public domain geocode system invented in 2008 by Gustavo Niemeyer which encodes a geographic location into a short string of letters and digits. Similar ideas were introduced by G.M. Morton in 1966. It is a hierarchical spatial data structure which subdivides space into buckets of grid shape, which is one of the many applications of what is known as a Z-order curve, and generally space-filling curves.
SABAP2 is the acronym for the Southern African Bird Atlas Project 2, which is the follow-up to the Southern African Bird Atlas Project. The first atlas project took place from 1987 to 1991. The current project was a joint venture between the Animal Demography Unit at the University of Cape Town, BirdLife South Africa, and the South African National Biodiversity Institute (SANBI). Following the closure of the Animal Demography Unit, the project is now managed by the FitzPatrick Institute of African Ornithology, University of Cape Town. The project aims to map the distribution and relative abundance of birds in southern Africa, and the original atlas area included South Africa, Lesotho, and Eswatini, although since 2012 the project has expanded to include Namibia, Botswana, Zimbabwe and Mozambique. SABAP2 was launched on 1 July 2007. The field work for this project is conducted by more than 1700 volunteers, known as citizen scientists – they collect the data in the field at their own cost and in their own time. As such they make a huge contribution to the conservation of birds and their habitat.
The Southern African Bird Atlas Project (SABAP) was conducted between 1987 and 1991. Because a new bird atlas was started in southern Africa in 2007, the earlier project is now referred to as SABAP1. The new atlas project is known as the Second Southern African Bird Atlas Project, and is abbreviated to SABAP2. The project is ongoing, and is now managed by the FitzPatrick Institute of African Ornithology at the University of Cape Town. Most of the data capture happens through the application BirdLasser. The project is currently funded by BirdLife South Africa and the South African National Biodiversity Institute.
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. In a usual grid-modeling strategy, to simplify position calculations, each region is represented by a point, abstracting the grid as a set of region-points. Each region or region-point in the grid is called a cell.
The Open Location Code (OLC) is a geocode based in a system of regular grids for identifying an area anywhere on the Earth. It was developed at Google's Zürich engineering office, and released late October 2014. Location codes created by the OLC system are referred to as "plus codes".
ICES Statistical Rectangles is a gridded, latitude-longitude based area notation system covering the north-east Atlantic region developed by the International Council for the Exploration of the Sea (ICES) in the 1970s, for simplified analysis and visualization of spatial data of relevance to that organization's interests. The individual rectangles that make up the system each measure 1 degree of longitude by 0.5 degrees of latitude and are intended to be roughly square in real world use in the ICES region of interest, approximately 30 nautical miles by 30 nautical miles at 60°N, although the actual width varies with latitude, gradually becoming wider than they are high south of 60°N, and narrower further north. The grid covers the region from 36°N to 85°30'N and from 44°W to 69°E using a set of alphanumeric identifiers, with row of latitude cited first, then column of longitude. The last used column identifier is M8; column identifiers A4-A9, and prefix "I" i.e. columns "I"0-"I"9 are not used. The resulting grid is 113 columns by 99 rows, comprising 11,187 labelled 1×0.5 degree cells. An example cell designation is 37F3, which designates the 1×0.5 degree rectangle of which the south-west corner is 54°00'N, 03°00'E. The grid covers both land and sea areas across its designated region, but as per the interests of its originating body, is typically employed for use with marine data such as analysis of marine resources, fishing activities, seabed habitat, etc., refer example references below. The full extent of the grid is visible in published figures such as Figs. 5-8 in Williamson et al., 2017.
References
- ↑ HARRISON, J.A., ALLAN, D.G., UNDERHILL, L.G., HERREMANS, M., TREE, A.J., PARKER, V. & BROWN, C.J. (1997) The atlas of southern African birds. Vols 1 and 2, BirdLife South Africa, Johannesburg, South Africa.
- ↑ Larsen, R.; Holmern, T.; Prager, S.D.; Maliti, H.; Røskaft, E. (2009). "Using the extended quarter degree grid cell system to unify mapping and sharing of biodiversity data". African Journal of Ecology. 47 (3): 382–392. doi:10.1111/j.1365-2028.2008.00997.x.
- ↑ Elith, J., Phillips, S. J., Hastie, T., Dudík, M., Chee, Y. E., & Yates, C. J. (2011). A statistical explanation of MaxEnt for ecologists. Diversity and distributions, 17(1), 43-57.