Map projections are introduced on pages 1012, and pages. A copy of the license is included in the section entitled gnu free documentation license. Conical projections use the projection of the globe onto a. Family of cylindrical map projection nisa manzoor nasir mughal 2.
State plane coordinate systems are built on map projections. Like conic projections, cylindrical projections can also have tangent or. Mercator distorts the size of geographical objects because its linear scale increases with the increase in latitude. However, to maintain accuracy for largerscale maps scales of 1. Map makers have devised methods for taking points on the curved surface of the earth and projecting them onto a flat surface. 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. It will also describe another unique map projection that could be used as well. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level.
The mercator projection is a cylindrical projection that was developed for navigation purposes. Gps constellation consists of 24 satellites that orbit the earth in 12 hours. Selecting a map projection national geographic society. We will focus rst on cylindrical projections but there are others. Map projection means representing a portion of the actual earth on a plane. Map projections massachusetts institute of technology. A sound knowledge of map projections and grids requires an understanding of the mathematical nature of projections and the size and shape of the earth, since in our context. Oct 01, 2015 types of map projections many types of map projections are being used for map making. Planar, azimuthal or zenithal projection conic projection cylindrical projection mathematical or conventional projection. 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. Jun 10, 2014 family of cylindrical map projection 1.
The equal earth map projection is a new equalarea pseudocylindrical projection for world maps. It looks similar to the widely used robinson projection, but unlike the robinson projection, retains. Media in category maps with conical projection the following 12 files are in this category, out of 12 total. What two ways is a cylindrical map projection distorted. Done for hundreds of years to create paper maps, it continues, but map projection today is most often really a mathematical procedure done in a computer. The mercator projection was used for its portrayal of direction and shape, so it was helpful to the sailors of that time. Page 79 discuss map scale and the basics of coordinate systems. No projection allows us to flatten the globe without distorting it. Although the projection procedure inevitably introduces systematic spatial distortions, particular types of distortion can be minimized to suit the geographic scope and intended use of the map data. Mathematical cartography also takes in map scales and their variation, the. If north or south is straight up, the aspect is said to be equatorial. A cylindrical projection can be imagined in its simplest form as a cylinder that has been wrapped around a globe at the equator.
Topic simple cylindrical map projection cylindrical equal area projection mercators projection cylindrical orthomorphic projection transverse mercators projectionalso called utm. Ppt chapter 2 map projection powerpoint presentation. Family of cylindrical map projection linkedin slideshare. A map projections aspect is its orientation on the page or display screen. Therefore, there is a family of planar projections, a family of cylindrical projections, and another. A free powerpoint ppt presentation displayed as a flash slide show on id. The ellipses show how imaginary circles on the globe are deformed because of a particular. A map projection property is an alteration of area, shape, distance, and direction on a. A map projection is a method for taking the curved surface of the earth and displaying it on something flat, like a computer screen or a piece of paper. Geological survey usgs now uses several of the more common projections for its published maps. 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.
Additionally, it will describe the custom map projection used by alliant energy in its corporate gis. Map projections used by the us geological survey usgs. A great variety of map projections has been devised to provide for the various properties that may be desired in maps. It is called orthophanic meaning right appearing as it uses tabular coordinates rather than mathematical formulas to make the map look right no point is completely free of distortion and there is considerable distortion near the poles. Pseudocylindrical projection outlines tend to be barrelshaped rather than rectangular. 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. Pdf the recently introduced adaptive composite map projection. A projection showing accurate areas is called an equalarea map. Adaptive composite map projections accepted author. At larger scales, a combination of the lambert cylindrical, the polar. Ardenclose novelty projection eastern hemisphere ardenclose novelty projection world ardenclose novelty projection world lambda2. The term map projection can be thought of literally as a projection. Map projections cylindrical projection a cylindrical projection map is the most common type of map that we see. Little deformation at the standard line equator but high distortion near the poles.
This is a summary of map projections that have articles of their own on wikipedia or that are otherwise notable. Map projections are roughly classi ed into the types of surfaces that the globe is projected onto. Another name for this map is a planar map how is an azimuthal map projection constructed. Over the years, cartographers have developed several ways to transfer the curved surface of earth onto flat maps. Training manual user guidemanual user guidemanual pdfs pyqgis. In romania, over time many cartographic projections were. Because there is no limit to the number of possible map projections, there can be no comprehensive list. The show link will display the projection in single view mode. After decades of using only one map projection, the polyconic, for its mapping program, the u. Cylindrical projection definition of cylindrical projection. A map projection is a way to flatten a globes surface into a plane in order to make a map.
The simplest approach is to ignore the problem of the earths shape, and this is a frequently employed solution to the problem. The purpose of this project is to complete the project assignments. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. It is perpendicular to the direction of gravity pull. Between those scales, choosing to use a sphere or spheroid will depend on. Gis positional data are primarily printed maps which have been digitized. 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 for the curvature of the earth to be taken into consideration. Map projection concerns the science of mathematical cartography, the techniques by which the earths dimensions, shape and features are translated in map form, be that twodimensional paper or two or three dimensional electronic representations. Often inappropriately used as a world map in atlases and wall chart. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. The best known map projection is named for its inventor, gerardus mercator, who developed it in 1569. A map projection is a systematic transformation of the latitudes and longitudes of positions on the surface of the earth to a.
For larger scale maps, including topographic quadrangles and the state base map series, conformal projections such as the transverse mercator and the. Map projection definition of map projection by the free. Map projections a map is a flat representation of earths curved surface. The projected graticule shown above is the result of an azimuthal equidistant projection in its normal polar aspect. To make these representations, the cartographer must calculate geographic features so that they are represented as close to real as possible. A map projection is the mathematical transformation of coordinates on a.
This means different y scales in different parts of the map what is the xscale factor. The relationship between a distance portrayed on a map and the same distance on the earth all three properties can be controlled through the scale factor scale factor grid projection length datum length scale factor is a ratio of a length on projection surface to the. The cylindrical equal area map projection is an example of an equal area. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Selecting a map projection c a rt o g ra p h ers a t n a t io n a l geo gra p h ic d is c us s h o w t h ey s elec t a n a p p ro p ria t e ma p p ro jec t io n f o r t h e s ep t emb er 2012 is s ue. This is changing somewhat as more data are collected by gps. However, instead of projecting a light, cartographers use mathematical formulas to create projections. The following picture shows a global map created by merging local maps of two robots. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the shape of the geoid is irregular. Modified polyconic, international map of the world series 111.
Three large families of map projection, plus several smaller ones, are generally acknowledged. Maps are a twodimensional representation of a threedimensional world. Composite map projections combine several projections that are. At this scale, the difference between a sphere and a spheroid is not detectable on a map. A map projection in which the surface features of a globe are depicted as if projected onto a cylinder, typically positioned with the globe centered. 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. It became the standard map projection for navigation because of its unique property of representing any course of constant bearing as a straight segment. A map projection may combine several of these characteristics. Projection converting digital map from longitudelatitude to twodimension. The following formulas combine these steps in a form which may be. All cylindrical projections fill a rectangular plane. When the central axis of the developable surface is oriented eastwest, the projections aspect is. A map projection s aspect is its orientation on the page or display screen. It is also modeled more accurately as an oblate spheroid or an ellipsoid.
For larger scale maps, including topographic quadrangles and the state base map series, conformal projections such as the transverse mercator and the lambert conformal conic are used. Arno peters, a german historian and journalist, in 1973. Imagine placing the movie screen around the globe in a cylinder shape. A world map that isnt quite right when it comes to any individual criteria, but isnt as terribly wrong in any of them, either, as other formulae used to create projections. Distortion ellipses help us to visualize what type of distortion a map projection has caused, how much distortion occurred, and where it occurred. Given a cylindrical projection, the x scale must increase away from equator. Cylindrical projections if we want to understand the properties that a map has, it helps to rst understand what type of map projection we are dealing with. Apr 25, 2017 mercator projection is an example of cylindrical projection which became a standard map projection because of its ability to represent lines of steady course. This booklet provides a conceptual introduction to.
The three main families of map projections unwrapping the sphere to a plane. Planar projections are also called azimuthal because every planar projection preserves the property of azimuthality, directions azimuths from one or two points to all other points on the map. Cylindrical projection definition is a projection as of a sphere or a spheroid on the surface of a cylinder. The shape of the earth and the geodetic datum concept are covered on pages 46. Maps were devised because they are much easier to use, store, and transport than globes, and they facilitated the development of much larger. An azimuthal map is constructed by the projection of part of the globe onto a flat surface which touches the globe at only one point. Circumference of lines of latitude getting smaller, maps width staying constant. Some projections have equalarea properties, while others provide for conformal delineations in which, for small areas, the shape is.
Objectives coordinate systems and map projections for gis. In effect, a projection is a systematic method of drawing the earths meridians and parallels on a flat surface. Only a globe can represent accurately the shape, orientation, and relative area of the earths surface features. To sort the list, click the headline in the table head. The modern topographic map was also created to the scale 1. Notice that areas close to the equator have very little distortion. Mapmakers have developed hundreds of map projections, over several thousand years.
Types of map projections many types of map projections are being used for map making. These methods enable map makers to control the distortion that. Permission is granted to copy, distribute andor modify this document under the terms of the gnu free documentation license, version 1. They are basically classified into four groups in accordance with the map projection theory or the types of surfaces that are tangent with the globe. What are cylindrical map projections used for normally. Pdf a new pseudocylindrical equalarea projection for adaptive. Peter gervai, openstreetmap editor, answered this question in aug 23 2d paper maps try to represent a 3d nonflat object, which is not really possible without errors. The only map projection that shows true compass bearings for navigation of straight lines. In all the map projections we will be dealing with, the datum surface is a 3dimensional surface, either a sphere or ellipsoid, representing the earth. What is a map projection map projection definition. His major aim in developing this projection was to create a map on which the size of countries were accurately represented unlike on the mercator projection. The projection that results is depicted in this image. Coordinate reference system crs, map projection, on the fly.
The central focus of this book is on the theory of map projections. A family of map projections that includes as special cases mollweide projection, collignon projection, and the various cylindrical equalarea projections. An area shown on a map may be distorted in size, shape, distance, or direction. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. Some of the different types of map projections include cylindrical. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. The downsides of cylindrical map projections are that they are severely distorted at the poles. Proper usage and audio pronunciation plus ipa phonetic transcription of the word map projection. Mercator projection is an example of cylindrical projection which became a standard map projection because of its ability to represent lines of steady course. Transferring a curved surface to a flat map results in a distorted image of the curved surface.
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