Similarly sec 2.56° = 1.001, so a strip of width 5.12° (centred on the equator) is accurate to within 0.1% or 1 part in 1,000. In 1569 he created the Mercartor map projection. Interpretación Traducción The aspect ratio of his map is 198/120 = 1.65. Therefore, the Mercator projection is adequate for mapping countries close to the equator. It became the standard map projection for nautical purposes because of its ability to represent lines of constant course, known as rhumb lines or loxodromes, as straight segments that conserve the angles with the meridians. in any direction from a point on the equator corresponds to approximately 900 km. The map is thereby conformal. American Cartographer. Mercator projection translation in English-French dictionary. "A World Map on a Regular Icosahedron by Gnomonic Projection.". If α is neither 0 nor π then the above figure of the infinitesimal elements shows that the length of an infinitesimal rhumb line on the sphere between latitudes φ; and φ + δφ is a sec α δφ. Today, the use of the Mercator projection is not justified except by specific interests. F. English-Chinese geology dictionary (英汉地质大词典). A generator of a cylinder is a straight line on the surface parallel to the axis of the cylinder. Scegli tra immagini premium su Mercator Projection della migliore qualità. geography in cartography, any of numerous map projections of the terrestrial sphere on the surface of a cylinder that is then unrolled as a plane. English-Spanish dictionary of Geography . [1913 Webster] 1. Les coordonnées des contours résultent d'une simple conversion sur un plan des coordonnées géodésiques. Since α is constant on the rhumb this expression can be integrated to give, for finite rhumb lines on the Earth: Once again, if Δφ may be read directly from an accurate latitude scale on the map, then the rhumb distance between map points with latitudes φ1 and φ2 is given by the above. The corresponding distances for latitudes 20°, 40°, 60° and 80° are 846 km, 689 km, 450 km and 156 km respectively. Image of: Mercator. This is his famous world map of 1569. Najboljši sosed: prodajna mesta, akcije, ugodnosti, novice, dogodki, recepti in mnogo več. projection de Mercator transverse [ projection cylindrique conforme de Lambert | projection de Gauss | projection de Mercator transversale ] He even quantifies his statement: "When the great circle distances which are to be measured in the vicinity of the equator do not exceed 20 degrees of a great circle, or 15 degrees near Spain and France, or 8 and even 10 degrees in northern parts it is convenient to use rhumb line distances". cylindrical projection 圆柱投影. The graph shows the variation of the scale factor with latitude. magnetic directions, instead of geographical directions, Universal Transverse Mercator coordinate system, "Mercator Projection vs. Peters Projection, part 2", "Mercator Projection vs. Peters Projection, part 1", Table of examples and properties of all common projections, An interactive Java Applet to study the metric deformations of the Mercator Projection, Web Mercator: Non-Conformal, Non-Mercator (Noel Zinn, Hydrometronics LLC), Mercator's Projection at University of British Columbia, Map projection of the tri-axial ellipsoid, Early modern Netherlandish cartography, geography and cosmography, Dutch celestial cartography in the Age of Discovery, Dutch celestial and lunar cartography in the Age of Exploration, Dutch systematic mapping of the far southern sky, c. 1595–1599, Dutch commercial cartography in the Age of Discovery, Dutch corporate cartography in the Age of Discovery, Dutch maritime/nautical cartography in the Age of Discovery, Golden Age of Dutch exploration and discovery, Constellations created and listed by Dutch celestial cartographers, Dutch discovery, exploration and mapping of Svalbard, Dutch discovery, exploration and mapping of Jan Mayen, European exploration and mapping of Southern Africa, Great Southern Land/Great Unknown South Land, European maritime exploration of Australia, Dutch discovery, exploration and mapping of Australasia, Dutch discovery, exploration and mapping of Nova Hollandia, Dutch discovery, exploration and mapping of Tasmania/Van Diemen's Land, Dutch discovery, exploration and mapping of the Australian continent, Dutch discovery, exploration and mapping of the Australian mainland, Dutch discovery, exploration and mapping of Nova Zeelandia, Dutch exploration and mapping of Formosa/Taiwan, Dutch exploration and mapping of the East Indies, Dutch exploration and mapping of Southern Africa, Dutch exploration and mapping of South Africa, Dutch exploration and mapping of the Americas, Dutch exploration and mapping of the Pacific, Dutch discovery and exploration of Easter Island, Science and technology in the Dutch Republic, Golden Age of Dutch science and technology, Early modern Iberian (Spanish and Portuguese) cartography, First undisputed non-Indigenous discovery, exploration and mapping of Australasia, First published systematic uses of the triangulation method in modern surveying and mapmaking, First published use of the Mercator projection for maritime navigation, First printed nautical atlas in the modern sense, History of selenography / lunar cartography, First published scientific map of the Moon with a topographical nomenclature, History of uranography / celestial cartography, https://en.wikipedia.org/w/index.php?title=Mercator_projection&oldid=992995821, Short description is different from Wikidata, Articles with unsourced statements from July 2020, Articles with unsourced statements from February 2017, Wikipedia articles with SUDOC identifiers, Creative Commons Attribution-ShareAlike License, Greenland's real area is comparable to the, Africa appears to be roughly the same size as. La projection cartographique est un ensemble de techniques permettant de représenter la surface de la Terre dans son ensemble ou en partie sur la surface plane d'une carte. [18], The above formulae are written in terms of the globe radius R. It is often convenient to work directly with the map width W = 2πR. The act of throwing or shooting forward. A meridian of the map is a great circle on the globe but the continuous scale variation means ruler measurement alone cannot yield the true distance between distant points on the meridian. A modern Mercator projection map. Since ruler measurements can furnish the map ordinate y and also the width W of the map then y/R = 2πy/W and the scale factor is determined using one of the alternative forms for the forms of the inverse transformation: The variation with latitude is sometimes indicated by multiple bar scales as shown below and, for example, on a Finnish school atlas. The transformation equations and scale factor for the non-secant version are[20]. For the above model 1 cm corresponds to 1,500 km at a latitude of 60°. Narrower strips are better: sec 8° = 1.01, so a strip of width 16° (centred on the equator) is accurate to within 1% or 1 part in 100. Let us know if you have suggestions to improve this article (requires login). However, if the map is marked with an accurate and finely spaced latitude scale from which the latitude may be read directly—as is the case for the Mercator 1569 world map (sheets 3, 9, 15) and all subsequent nautical charts—the meridian distance between two latitudes φ1 and φ2 is simply. Being a cylindrical projection, the deformation experienced by the areas closest to the poles is such that Greenland (2,166,086 km²) is similar in extent to Africa (30,221,535 km²), when the actual data show that comparing both territories is simply crazy. It was the standard map projection for nautical purposes because of its ability to represent cruise lines, known as rhumb lines as segments that maintain constant angles with the meridians. Mercator or cylindrical map projection The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569. In the extreme case where the longitudinal separation is 180°, the distance along the parallel is one half of the circumference of that parallel; i.e., 10,007.5 km. At a latitude of ±25° the value of sec φ is about 1.1 and therefore the projection may be deemed accurate to within 10% in a strip of width 50° centred on the equator. The difference is small for short distances but increases as λ, the longitudinal separation, increases. The scale on the equator is 0.99; the scale is k = 1 at a latitude of approximately ±8° (the value of φ1); the scale is k = 1.01 at a latitude of approximately ±11.4°. The Mercator projection is a transformation of a cylindrical projection used for navigation. Only accurate Mercator projections of regions near the equator will necessitate the ellipsoidal corrections. /mɜˌkeɪtəz prəˈdʒɛkʃən/ (say mer.kaytuhz pruh jekshuhn) noun a map projection with rectangular grid which is conformal and on which any rhumb line is represented as a straight line. Often, it is innocent of the crimes it is accused of, and I want to address this as well as what it actually is guilty of. The scale factor is unity on the equator, as it must be since the cylinder is tangential to the ellipsoid at the equator. One problem is the variation of scale with latitude, and another is that straight lines on the map (rhumb lines), other than the meridians or the equator, do not correspond to great circles. The ordinate y of the Mercator projection becomes infinite at the poles and the map must be truncated at some latitude less than ninety degrees. The recommendations below are made by a complete layman! So my first recommendation is: Verify if you reallyneed a rectangular map or if a different shape might fit the purpose of the map better. (The value of e2 is about 0.006 for all reference ellipsoids.) Nicolas Tissot noted that the scale factors at a point on a map projection, specified by the numbers h and k, define an ellipse at that point. Any of the inverse transformation formulae may be used to calculate the corresponding latitudes: The figure comparing the infinitesimal elements on globe and projection shows that when α=β the triangles PQM and P′Q′M′ are similar so that the scale factor in an arbitrary direction is the same as the parallel and meridian scale factors: This result holds for an arbitrary direction: the definition of isotropy of the point scale factor. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Calling the ruler distances of the end points on the map meridian as measured from the equator y1 and y2, the true distance between these points on the sphere is given by using any one of the inverse Mercator formulæ: where R may be calculated from the width W of the map by R = W/2π. Mercator's original map is truncated at 80°N and 66°S with the result that European countries were moved towards the centre of the map. La projection de Mercator ou projection Mercator est une projection cartographique de la Terre, dite «cylindrique», tangente à l' équateur du globe terrestre sur une carte plane formalisée par le géographe flamand Gerardus Mercator, en 1569. ... cylindrical orthomorphic projection; cylindrite The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569. Mercator's\ projection Mercatori projektsioon. When α = π/2 or 3π/2 the rhumb corresponds to one of the parallels; only one, the equator, is a great circle. projection cylindrique oblique. Le choix d'une projection et la conversion d'une projection à une autre comptent parmi les difficulté que les cartographes ont du … Without a doubt, the most famous map projection is the Mercator projection. English: The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569. Article 4 : Le système de coordonnées planimétriques est constitué d’un référentiel géodésique et d’une ... - La Projection cartographique BFTM (projection cylindrique transverse de Mercator) ; When the Earth is modelled by a spheroid (ellipsoid of revolution) the Mercator projection must be modified if it is to remain conformal. For cylindrical projections, the axes of the ellipse are aligned to the meridians and parallels. Erläuterung Übersetzung The area scale factor is the product of the parallel and meridian scales hk = sec2φ. The interpretation of such bar scales is non-trivial. Longer distances require various approaches. For all other values it is a spiral from pole to pole on the globe intersecting all meridians at the same angle, and is thus not a great circle. The Mercator Projection is frequently used as a scapegoat by people who are surprised by certain geographical facts, mostly relating to distance or area. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Working from the projected map requires the scale factor in terms of the Mercator ordinate y (unless the map is provided with an explicit latitude scale). For Australia, taking 25° as a median latitude, hk = 1.2. Scopri le migliori foto stock e immagini editoriali di attualità di Mercator Projection su Getty Images. The length of the chord AB is 2(a cos φ) sin λ/2. The Mercator map was designed as an aid to navigators with straight lines, loxodromes or rhumb lines—representing lines of constant compass bearing—that are perfect for "true" direction. On peut obtenir ainsi trois types de projections : cylindrique, conique ou azimutale ... Mercator Projection - Duration: 3:12. On a Mercator projection, for example, the landmass of Greenland appears to be greater than that of the continent of South America; in actual area, Greenland is smaller than the Arabian Peninsula. In this case the maximum latitude attained must correspond to y = ±W/2, or equivalently y/R = π. These circles are rendered on the projected map with extreme variation in size, indicative of Mercator's scale variations. [16][19][e] For the Mercator projection, h = k, so the ellipses degenerate into circles with radius proportional to the value of the scale factor for that latitude. [17], There are many alternative expressions for y(φ), all derived by elementary manipulations. Even more extreme truncations have been used: a Finnish school atlas was truncated at approximately 76°N and 56°S, an aspect ratio of 1.97. - Les déformations cartographiques - Projection cylindrique, conique, azimutale - Carte Mercator, Peters Erratum : dia 18 - nous sommes "proches" / dia 18 et 19 : territoires et non pays.