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Polyconic Projection Class
Polyconic can refer either to a class of map projections or to a specific projection known less ambiguously as the American polyconic projection. Polyconic as a class refers to those projections whose parallels are all non-concentric circular arcs, except for a straight equator, and the centers of these circles lie along a central axis. This description applies to projections in equatorial aspect. Polyconic projections Some of the projections that fall into the polyconic class are: *American polyconic projection—each parallel becomes a circular arc having true scale, the same scale as the central meridian *Latitudinally equal-differential polyconic projection *Rectangular polyconic projection *Van der Grinten projection—projects entire earth into one circle; all meridians and parallels are arcs of circles. * Nicolosi globular projection—typically used to project a hemisphere into a circle; all meridians and parallels are arcs of circles. A series of polyconic projections, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Polyconic Projection
In the cartography of the United States, the American polyconic projection is a map projection used for maps of the United States and regions of the United States, its regions beginning early in the 19th century. It belongs to the polyconic projection class, which consists of map projections whose Circle of latitude, parallels are non-concentric circular Circular arc, arcs except for the equator, which is straight. Often the American polyconic is simply called the polyconic projection. The American polyconic projection was probably invented by Swiss-American cartographer Ferdinand Rudolph Hassler around 1825. It was commonly used by many map-making agencies of the United States from the time of its proposal until the middle of the 20th century.''Flattening the Earth: Two Thousand Years of Map Projections'', John P. Snyder, 1993, pp. 117-122, . It is not used much these days, having been replaced by Map projection#Conformal, conformal projections in the State Plane Coordinate Syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Grinten Projection SW
A van is a type of road vehicle used for transporting goods or people. There is some variation in the scope of the word across the different English-speaking countries. The smallest vans, microvans, are used for transporting either goods or people in tiny quantities. Mini MPVs, compact MPVs, and MPVs are all small vans usually used for transporting people in small quantities. Larger vans with passenger seats are used for institutional purposes, such as transporting students. Larger vans with only front seats are often used for business purposes, to carry goods and equipment. Specially equipped vans are used by television stations as mobile studios. Postal services and courier companies use large step vans to deliver packages. Word origin and usage Van meaning a type of vehicle arose as a contraction of the word caravan. The earliest records of a van as a vehicle in English are in the mid-19th century, meaning a covered wagon for transporting goods; the earliest reported rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Map Projection
In cartography, a map projection is any of a broad set of Transformation (function) , transformations employed to represent the curved two-dimensional Surface (mathematics), surface of a globe on a Plane (mathematics), plane. In a map projection, coordinates, often expressed as latitude and longitude, of locations from the surface of the globe are transformed to coordinates on a plane. Projection is a necessary step in creating a two-dimensional map and is one of the essential elements of cartography. All projections of a sphere on a plane necessarily distort the surface in some way. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. The study of map projections is primarily about the characterization of their distortions. There is no limit to the number of possible map projections. More generally, proje ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
American Polyconic Projection
In the cartography of the United States, the American polyconic projection is a map projection used for maps of the United States and regions of the United States, its regions beginning early in the 19th century. It belongs to the polyconic projection class, which consists of map projections whose Circle of latitude, parallels are non-concentric circular Circular arc, arcs except for the equator, which is straight. Often the American polyconic is simply called the polyconic projection. The American polyconic projection was probably invented by Swiss-American cartographer Ferdinand Rudolph Hassler around 1825. It was commonly used by many map-making agencies of the United States from the time of its proposal until the middle of the 20th century.''Flattening the Earth: Two Thousand Years of Map Projections'', John P. Snyder, 1993, pp. 117-122, . It is not used much these days, having been replaced by Map projection#Conformal, conformal projections in the State Plane Coordinate Syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latitudinally Equal-differential Polyconic Projection
The latitudinally equal-differential polyconic projection ( 等差分纬线多圆锥投影) is a polyconic map projection in use since 1963 in mainland China. Maps on this projection are produced by China's State Bureau of Surveying and Mapping and other publishers. Its original method of construction has not been preserved, but a mathematical approximation has been published. Description As a polyconic projection, the parallels are arcs of circles that are not concentric. The points of no distortion are on the central meridian at 44°N/S latitude. Meridians are convex away from the straight central meridian, and parallels are gently concave away from the equator. The projection is neither equal-area nor conformal; rather, it is a compromise projection. Maps on this projection do not show the north pole, instead cropping the high latitudes along a straight line whose latitude varies but that never reaches the pole. By convention, the projection is centered at 150° such that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rectangular Polyconic Projection
The rectangular polyconic projection is a map projection was first mentioned in 1853 by the United States Coast Survey, where it was developed and used for portions of the U.S. exceeding about one square degree. It belongs to the polyconic projection class, which consists of map projections whose parallels are non-concentric circular arcs except for the equator, which is straight. Sometimes the rectangular polyconic is called the War Office projection due to its use by the British War Office for topographic maps. . It is not used much these days, with practically all military grid systems having moved onto conformal projection systems, typically modeled on the transverse Mercator projection. Description The rectangular polyconic has one specifiable latitude (along with the latitude of opposite sign) along which scale is correct. The scale is also true on the central meridian of the projection. Meridians are spaced such that they meet the parallels at right angles in equatorial aspe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Van Der Grinten Projection
The van der Grinten projection is a compromise map projection, which means that it is neither equal-area nor conformal. Unlike perspective projections, the van der Grinten projection is an arbitrary geometric construction on the plane. Van der Grinten projects the entire Earth into a circle. It largely preserves the familiar shapes of the Mercator projection while modestly reducing Mercator's distortion. Polar regions are subject to extreme distortion. Lines of longitude converge to points at the poles.''Flattening the Earth: Two Thousand Years of Map Projections'', John P. Snyder, 1993, pp. 258–262, . History Alphons J. van der Grinten invented the projection in 1898 and received US patent #751,226 for it and three others in 1904.''A Bibliography of Map Projections'', John P. Snyder and Harry Steward, 1989, p. 94, US Geological Survey Bulletin 1856. The National Geographic Society adopted the projection for their reference maps of the world in 1922, raising its visibility ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicolosi Globular Projection
The Nicolosi globular projection is a polyconic map projection invented about the year 1000 by the Iranian polymath al-Biruni. As a circular representation of a hemisphere, it is called ''globular'' because it evokes a globe. It can only display one hemisphere at a time and so normally appears as a "double hemispheric" presentation in world maps. The projection came into use in the Western world starting in 1660, reaching its most common use in the 19th century. As a "compromise" projection, it preserves no particular properties, instead giving a balance of distortions. History Abū Rayḥān Muḥammad ibn Aḥmad Al-Bīrūnī, who was the foremost Muslim scholar of the Islamic Golden Age, invented the first recorded globular projection for use in celestial maps about the year 1000. Centuries later, as Europe entered its Age of Discovery, the demand for world maps increased rapidly, sparking a vast experimentation with diverse map projections. Globular projections were one cate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Map Projections
This is a summary of map projections that have articles of their own on Wikipedia or that are otherwise WP:NOTABLE, notable. Because there is no limit to the number of possible map projections, there can be no comprehensive list. Table of projections *The first known popularizer/user and not necessarily the creator. Key Type of projection surface ; Cylindrical: In normal aspect, these map regularly-spaced meridians to equally spaced vertical lines, and parallels to horizontal lines. ; Pseudocylindrical: In normal aspect, these map the central meridian and parallels as straight lines. Other meridians are curves (or possibly straight from pole to equator), regularly spaced along parallels. ; Conic: In normal aspect, conic (or conical) projections map meridians as straight lines, and parallels as arcs of circles. ; Pseudoconical: In normal aspect, pseudoconical projections represent the central meridian as a straight line, other meridians as complex curves, and parallels as ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
