In geography, the centroid of the two-dimensional shape of a region of the Earth's surface (projected radially to sea level or onto a geoid surface) is known as its geographic centre or geographical centre or (less commonly) gravitational centre. Informally, determining the centroid is often described as finding the point upon which the shape (cut from a uniform plane) would balance.[1] This method is also sometimes described as the "gravitational method".[2]
One example of a refined approach using an azimuthal equidistant projection, also potentially incorporating an iterative process, was described by Peter A. Rogerson in 2015.[3][4] The abstract says "the new method minimizes the sum of squared great circle distances from all points in the region to the center". However, as that property is also true of a centroid (of area), this aspect is effectively just different terminology for determining the centroid.
In 2019, New Zealand's GNS Science also used an iterative approach (and a variety of different projections) when determining a centre position for New Zealand's Extended Continental Shelf.[5]
However, other methods have also been proposed or used to determine the centres of various countries and regions. These include:
centroid of volume (incorporating elevations into calculations), instead of the more usual centroid of area as described above.[6]
centre point of a bounding box completely enclosing the area. While relatively easy to determine, a centre point calculated using this method will generally also vary (relative to the shape of the landmass or region) depending on the orientation of the bounding box to the area under consideration. In this sense it is not a robust method.
finding the longitude that divides the region into two equal area parts to the east and west, and then similarly the latitude that divides the region into two equal area parts to the north and south.[7] Like the bounding box approach described above this method would not generally locate precisely the same point if the same shaped region was oriented differently.
As noted in a United States Geological Survey document, "There is no generally accepted definition of geographic center, and no completely satisfactory method for determining it."[1]
In general, there is room for debate around various details such as whether or not to include islands and similarly, large bodies of water, how best to handle the curvature of the Earth (a more significant factor with larger regions) and closely related to that issue, which map projection to use.
^ ab"Geographic Centers of the United States". United States Geologic Survey: 4. 1964.
^"Where is the centre of Great Britain?". Retrieved 1 September 2019.
^Rogerson, Peter A. (2015-10-02). "A New Method for Finding Geographic Centers, with Application to U.S. States". The Professional Geographer. 67 (4): 686–694. doi:10.1080/00330124.2015.1062707. ISSN 0033-0124. S2CID 128954218.
^"Where's your county seat? A modern mathematical method for calculating centers of geography".
^"Art Meets Science: The Centre of New Zealand's Continental Shelf" (PDF).
^"Clipping from Nelson Mail, 27 June 1962 edition, sourced from GNS library". Retrieved 12 March 2019.
^(PDF). Archived from the original (PDF) on 2013-06-13. Retrieved 2014-11-19. {{cite web}}: External link in |title= (help)
External links
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January 31, 2023
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In geography the centroid of the two dimensional shape of a region of the Earth s surface projected radially to sea level or onto a geoid surface is known as its geographic centre or geographical centre or less commonly gravitational centre Informally determining the centroid is often described as finding the point upon which the shape cut from a uniform plane would balance 1 This method is also sometimes described as the gravitational method 2 One example of a refined approach using an azimuthal equidistant projection also potentially incorporating an iterative process was described by Peter A Rogerson in 2015 3 4 The abstract says the new method minimizes the sum of squared great circle distances from all points in the region to the center However as that property is also true of a centroid of area this aspect is effectively just different terminology for determining the centroid In 2019 New Zealand s GNS Science also used an iterative approach and a variety of different projections when determining a centre position for New Zealand s Extended Continental Shelf 5 However other methods have also been proposed or used to determine the centres of various countries and regions These include centroid of volume incorporating elevations into calculations instead of the more usual centroid of area as described above 6 centre point of a bounding box completely enclosing the area While relatively easy to determine a centre point calculated using this method will generally also vary relative to the shape of the landmass or region depending on the orientation of the bounding box to the area under consideration In this sense it is not a robust method finding the longitude that divides the region into two equal area parts to the east and west and then similarly the latitude that divides the region into two equal area parts to the north and south 7 Like the bounding box approach described above this method would not generally locate precisely the same point if the same shaped region was oriented differently As noted in a United States Geological Survey document There is no generally accepted definition of geographic center and no completely satisfactory method for determining it 1 In general there is room for debate around various details such as whether or not to include islands and similarly large bodies of water how best to handle the curvature of the Earth a more significant factor with larger regions and closely related to that issue which map projection to use Contents 1 Notable geographical centres 1 1 Geographic centres in Africa 1 2 Geographic centres in Asia 1 3 Geographic centres in Europe 1 4 Geographic centres in North America 1 5 Geographic centres in Oceania 1 6 Geographic centres in South America 2 See also 3 References 4 External linksNotable geographical centres EditGeographical centre of Earth Axis mundi Omphalos of DelphiGeographic centres in Africa Edit Geographic Centre of Uganda Amolatar Monument Geographic centres in Asia Edit Geographical midpoints of Asia in China or Russia Geographical centre of India 8 Zero Mile Stone Nagpur Geographic center of Iran Geographic centre of Sri Lanka Geographical centre of the Korean Peninsula Geographical centre of the Philippines Geographical centre of the Russian Federation Geographical centre of the Soviet Union Geographic center of TaiwanGeographic centres in Europe Edit Geographical midpoint of Europe Geographical centre of Austria Geographic center of Belarus Geographical centre of Belgium Geographical centre of Estonia Geographical centre of Germany Central Germany geography Geographical centre of Hungary Geographical centre of Ireland Geographical centre of Lithuania Geographical centre of Norway Geographical centre of Poland Geographical center of Romania Geographical centre of the Russian Federation Geographical centre of Serbia Geographical centre of Slovenia Geographical centre of the Soviet Union Geographical center of Sweden Geographical centre of Switzerland Centre points of the United Kingdom Geographical centre of Great Britain Centre points of counties of the United Kingdom Geographic centre of England Geographical centre of Scotland Geographic centre of WalesGeographic centres in North America Edit Geographic center of North America Geographic centre of Canada Geographic center of the United States List of geographic centers of the United StatesGeographic centres in Oceania Edit Centre points of Australia Geographic centre of New ZealandGeographic centres in South America Edit Geographical Center of South America Geographical Center of ColombiaSee also EditExtremes on Earth Pole of inaccessibility Center of populationReferences Edit a b Geographic Centers of the United States United States Geologic Survey 4 1964 Where is the centre of Great Britain Retrieved 1 September 2019 Rogerson Peter A 2015 10 02 A New Method for Finding Geographic Centers with Application to U S States The Professional Geographer 67 4 686 694 doi 10 1080 00330124 2015 1062707 ISSN 0033 0124 S2CID 128954218 Where s your county seat A modern mathematical method for calculating centers of geography Art Meets Science The Centre of New Zealand s Continental Shelf PDF Clipping from Nelson Mail 27 June 1962 edition sourced from GNS library Retrieved 12 March 2019 Geographic Center of South America Geographical Center of India Internet Archive copy archived from the original http dcmsme gov in dips betul pdf PDF Archived from the original PDF on 2013 06 13 Retrieved 2014 11 19 a href Template Cite web html title Template Cite web cite web a External link in code class cs1 code title code help External links Edit Wikimedia Commons has media related to Geographical centres This article includes a list of related items that share the same name or similar names If an internal link incorrectly led you here you may wish to change the link to point directly to the intended article Retrieved from https en wikipedia org w index php title Geographical centre amp oldid 1130172690, wikipedia, wiki, book, books, library,
