A mathematical formula that is a variant of the mercator, cylindrical, projection. Geological survey usgs now uses several of the more common projections for its published maps. Some common examples are cones, cylinders, and planes. You can convert from any of the available projections to any of the available projections, and new projections will be added soon. The equator is the normal aspect or viewpoint for these projections. A map projection is any of many methods used in cartography mapmaking to represent the twodimensional curved surface of the earth or other body on a plane. Globus map projector my new map projector which works in web browser. A map projections aspect is its orientation on the page or display screen. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The name of the projection is the shape that the image is projected onto.
Cylindrical projection wrap a sheet of paper around the globe in the form of a cylinder, transfer the geographic features of the globe on to it. A map projection is a way of representing the surface of a celestial sphere on a flat surface. The mercator projection was used for its portrayal of direction. Cylindrical projection definition at, a free online dictionary with pronunciation, synonyms and translation. It is currently incomplete in four ways, two diagrams are missing. Map projections explained a beginners guide youtube. The lambert azimuthal equalarea projection is mathematically based on a plane tangent to the earth.
Mercator projection is an example of cylindrical projection which became a standard map projection because of its ability to represent lines of steady course. Scale increases perpendicular to the radii toward the periphery. The best known map projection is named for its inventor, gerardus mercator, who developed it in 1569. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Map projections are introduced on pages 1012, and pages. It is often described as a cylindrical projection, but it must be derived mathematically. The graticule of a geographic coordinate system is projected onto a cylindrical projection surface. Advances in smallscale map projection research openedition.
Snyder, 1987 an album of map projections usgs pp 1453, j. Article pdf available in cartographic perspectives 201478. Slideshare uses cookies to improve functionality and performance, and to. The points on the spherical grid are transferred to the cylinder which is then unfolded into a flat plane. If it is tangential to a point between the pole and the equator, it is called the oblique projection. As mentioned above, the correctness of area, shape, direction and distances are the four major global properties to be. Pdf introducing the patterson cylindrical projection researchgate. Each rectangular grid cell has the same size, shape, and area. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. Each map projection has specific properties that make it useful for specific purposes. This model should be more or less spheroid having the length of polar diameter lesser than equatorial and on this model the network of graticule can be transferred b.
Map projections massachusetts institute of technology. The beginning of the book contains substantial introductory information about map projection families and distortions. Antiti map projections tn 6 a map is a representation of all or part of the earth drawn on a flat surface at a specific scale. Pdf a guide to selecting map projections for world and. A map projection is the method to represent the spherical surface or object like that in two dimensional plane or flat surface. A map projection uses mathematical formulas to relate the spherical or ellipsoidal coordinates on. However, they do resemble cylindrical projections, with straight and parallel latitude lines, and can have equally spaced meridians, but meridians are curves, not straight lines. Pseudocylindrical projection outlines tend to be barrelshaped rather than rectangular.
Cartographers consider the choice of projection based on the area displayed and the purpose of the map i. When the central axis of the developable surface is oriented eastwest, the projections aspect is. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. This simple cylindrical projection converts the globe into a cartesian grid. At this scale, the difference between a sphere and a spheroid is not detectable on a map.
If the graticule of latitude and longitude are projected onto the cylinder and the cylinder unwrapped, then a gridlike pattern of straight lines of latitude and longitude would result. While the areas near the equator are the most likely to be accurate compared to the actual earth, the parallels and meridians being straight lines dont allow. The only factor that distinguishes different cylindrical map projections from one another is the scale used when spacing the parallel lines on the map. The shape of the earth and the geodetic datum concept are covered on pages 46. The problem with a map projection is that they are never entirely accurate. Cylindricalmathematically projected on a cylinder tangent to the equator. Map projection is the method of transferring the graticule of latitude and longitude on. Because there is no limit to the number of possible map projections, there can be no comprehensive list. Although they can represent size, shape, distance and directions of the earth features with reasonable accuracy, globes are not practical or suitable for many applications. The meridians are equally spaced parallel vertical lines, and the parallels of latitude are parallel horizontal straight lines that are spaced farther and farther apart as their distance from the equator increases. A cylindrical projection can be imagined in its simplest form as a cylinder that has been wrapped around a globe at the equator. Lecture 2 map projections and gis coordinate systems. Map projection formed by projecting points and lines from globe onto cone, it is accurate of small areas but has lots of distortion for large areas. Page 79 discuss map scale and the basics of coordinate systems.
Ellipsoid coordinates are transferred onto a developable surface using the formulas of the spherical mercator stefanakis 2015. The mercator projection was used for its portrayal of direction and shape, so it was helpful to the sailors of that time. After decades of using only one map projection, the polyconic, for its mapping program, the u. This is particularly the case for cylindrical projections, which are known for their extreme and visually disturbing rate of distortion away from the standard parallels. If north or south is straight up, the aspect is said to be equatorial. Because maps are flat, some of the simplest projections are made onto geometric shapes that can be flattened without stretching their surfaces. However, to maintain accuracy for largerscale maps scales of 1. Map projection pdf importance of map projection uses of map projection conic map projection cylindrical map projection azimuthally map projection. Cylindrical map projections are rectangles, but are called cylindrical because they can be rolled up and their edges mapped in a tube, or cylinder.
But this method produces distortion, so a map projection today may be created using. The mercator projection is a cylindrical projection that was developed for navigation purposes. A map projection systematically projects locations from the surface of a spheroid to representative positions on a flat surface using mathematical algorithms. Conic projection definition of conic projection by the. It is also known as the babinet projection, homalographic projection, homolographic projection, and elliptical projection. D h maling, coordinate systems and map projections. All cylindrical projections fill a rectangular plane. The equal earth map projection is a new equalarea pseudocylindrical projection for world maps. Originally, this and other map projections were achieved by a systematic method of drawing the earths meridians and latitudes on the flat surface. State plane is a common projection for all states in the usa conic and utm variants utm is commonly used and is a good choice when the eastwest width of area does not exceed 6 degrees utm projection universe transverse mercator conformal projection shapes are preserved cylindrical surface two standard meridians zones are 6 degrees of. A map projection is used to portray all or part of the. The best known map projection is named for its inventor. So therefore, there are both distortion and projection.
Between those scales, choosing to use a sphere or spheroid will depend on. Map projection a map projection is a systematic representation of a round body such as the earth or a flat plane surface. It looks similar to the widely used robinson projection, but unlike the robinson projection, retains. It is also modeled more accurately as an oblate spheroid or an ellipsoid. The term normal cylindrical projection is used to refer to any projection in which meridians are mapped to equally spaced vertical lines and circles of latitude are mapped to horizontal lines or, mutatis mutandis, more generally, radial lines from a fixed point are mapped to equally spaced parallel lines and concentric circles around it are mapped to perpendicular lines. In this section, by an elementary method, we show the cylindrical method that. Cylindrical projections aire obtained when it cylinder is used as the. We will taker a closer look at the popular mercator projection and examine how the projection. The term projection here refers to any function defined on the earths surface and with values on the plane, and not necessarily a geometric projection. The downsides of cylindrical map projections are that they are severely distorted at the poles. Learn what a map projection is, why they are used and what impact they have on maps gis systems.
Maps were devised because they are much easier to use, store, and transport than globes, and they facilitated the development of much larger. A map is a projection of data usually from the real earth. Mercator distorts the size of geographical objects because its linear scale increases with the increase in latitude. Snyder, pdf, 1997 cegis map projection bibliography usgs, database, 2011 map projections a working manual usgs pp 95, j. Cylindrical projection, in cartography, any of numerous map projections of the terrestrial sphere on the surface of a cylinder that is then unrolled as a plane.
It is the only projection that can accurately represent both areas and true direction from the center of the projection. Map projections, map projections flashcards quizlet. Miller cylindrical robinson sinusoidal equal area orthographic stereographic. Mercator projection, type of map projection introduced in 1569 by gerardus mercator.
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