And so when a map projection or when we use map projection, will always have distortion of the shape, the area, the distance, and direction. To sort the list, click the headline in the table head. The recommendations below are a simplification of whats on the web. Map scale is concerned with reducing geographical features of interest to manageable proportions, coordinate systems help us define the positions of features on the surface of the earth, and map projections are concerned with moving from. Map projections are often named after the mathematician or inventor responsible for arithmetic formula. Handbook for transformation of datums, projections, grids. Geological survey have designed projections for their specific needs such as the space oblique. In addition, a number of map projections are based on polyhedra. Scale changes in one direction to be offset by scale changes in the other direction. Although they can represent size, shape, distance and directions of the earth features with reasonable accuracy, globes are not.
Cylindrical wrap a piece of paper around the earth to form a cylinder that touches the equater all the way around the earth. Circumference of lines of latitude getting smaller, maps width. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. A projection is a way to make a flat representation of the earth. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. We hope that the following list of synonyms for the word map projection will help you to finish your crossword today. We hope that the following list of synonyms for the word map projection will help you to. It is perpendicular to the direction of gravity pull. In effect, a projection is a systematic method of drawing the earths meridians and parallels on a flat surface. Given a cylindrical projection, the x scale must increase away from equator. Map projections page 6 north american datums there are two geodetic datums in common use in north america.
Bills quick guide to map projections simple rules for simple maps a full catalog of all the projections available in arcgis is available on my website. The north american datum of 1927 nad27 is an example of a regional datum, in which the ellipsoid clarke 1866 is tied to an initial point of reference on the surface. Since the earth is roughly the shape of an oblate spheroid, map projections are necessary for creating maps of the earth or parts of the earth that are represented on a plane such as a piece of paper or a computer screen. It defines the origin and orientation of latitude and longitude lines. 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. Be sure to include information about the surface and distortion characteristics, and examples of instances where these projections are used.
Over the years since its first appearance, datums and map projections has become a key book for many students and professionals around the world. Map projections coach grigg ap human geography golf. The revisions take into account the huge advances in geometrical geodesy which have occurred since the early years of satellite geodesy. While retaining the benefits of the first edition clear presentation assuming no prior knowledge, a problemsolving approach, practical examples and. The post1973 editions of the alaska map e more nearly approximate an equidistant conic map projection. The beginning of the book contains substantial introductory information about map projection families and distortions. For remote sensing, gis and surveying has become a key book for many students and professionals around the world. Coordinate systems, map projections, and geographic datum. Snyder, 1987 an album of map projections usgs pp 1453, j.
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. The study of map projections is the characterization of these 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. If youre interested, take a look here for a much more extensive and technical introduction to projections. Some projections have equalarea properties, while others provide for conformal delineations in which, for small areas, the shape is. Geodesy, coordinate systems, and map projections objectives introduce the main concepts of geodesy coordinate systems, datums, ellipsoids, and geoids describe map projections and coordinate systems we use in gis two key questions what is the shape of the earth, and where are things on the earth.
An album of map projections should enable read ers to sharpen and in some cases to correct their knowledge of the distances, directions, and relative areas of the world. Learn quiz map projections with free interactive flashcards. Map projections are important in creating maps with map projections distorting the surface in some way. They are used to classify the majority of projections, including some that are not analytically geometrically constructed. Datums, coordinate systems, coordinate reference systems and datum transformations dean c. Although there has been no dearth of valuable books describing a wide range of map projec tions, an album of map projections is the. Some projections have equalarea properties, while others provide for conformal delineations in which, for small areas, the shape. Its theme a practical guide to coordinate reference systems is as important now as when it was first published, probably more so when we consider the ever growing use of satellite navigation. The geoid, ellipsoid, spheroid and datum what are map projections. The issues in the different types of map projections are issues of scale. Map scale is concerned with reducing geographical features of interest to manageable proportions, coordinate systems help us define the positions of features on the surface of the earth, and map projections are concerned with moving from the threedimensional world to the two dimensions of a flat map or display, all of which are discussed in. Since its introduction in 1903, the swiss national survey has used the uniform map projection swiss grid. Because earth has a curving, notquite sphericial shape, planar maps of.
Coordinate systems and map projections 2nd edition. A map projection is a geometric function that transforms the earths curved, ellipsoidal surface onto a flat, 2dimensional plane. And now we can project and unproject massive quantities of coordinates, transforming them backward and forward from latitude and longitude assuming this or that earth model to overlay precisely with data that are stored in some other coordinate space. Map projections are attempts to portray the surface of the earth or a portion of the earth on a flat surface. The separately named largescale projections that are the focus of the epsg database, for example, are almost all just parameterizations of smallscale projections. More precisely, a map projection requires a transformation from a set of two independent coordinates on the model of the earth the latitude. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. This is a digital copy of a book that was preserved for. Map projections page 3 introduction to map projections although earth images and map data that you use are typically rendered onto flat surfaces such as your computer screen or a sheet of paper, the earths surface obviously is not flat. It is also modeled more accurately as an oblate spheroid or an ellipsoid.
The goal here is to make quick, easy reference maps for illustrations, not to cover every special case or technicality. Types of map projections many types of map projections are being used for map making. Pdf map projections download full pdf book download. A coordinate system is a reference system used to represent the locations of geographic features, imagery, and observations, such as global positioning system gps locations, within a common geographic framework. Map projections are a systematic transformation of longitudes and latitudes of a location on the surface of the sphere. Articulate the leader in rapid elearning and communications. Advances in smallscale map projection research openedition. A practical guide to coordinate reference systems, datums and map projections. Because there is no limit to the number of possible map projections, there can be no comprehensive list. 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. The first half of the book focuses on datums, exploring different coordinate systems and datums, including two and threedimensional representations of earth. Pdf, 1997 cegis map projection bibliography usgs, database, 2011 map projections a working manual usgs pp 95, j. This bestselling title has become a vital text for students an. Iliffe 2008 paperback iliffe, jonathan, lott, roger on.
Coordinate systems enable geographic datasets to use common locations for integration. Map projection crossword answers, clues, definition. After watching this video, you will be able to explain what a map projection is, what a map scale is, and why they need to be carefully chosen when creating a map. The show link will display the projection in single view mode. Maps were devised because they are much easier to use, store, and transport than globes, and they facilitated the development of much larger scaled representations than was the case with a globe. Map projections is about presenting the round earth on a flat surface.
There is no limit to the number of possible map projections 1 projections are a subject of several pure mathematical fields, including differential geometry, projective geometry, and manifolds. Equivalent or equal area projections a map areaof a given size, a circle three inches in diameter for instance, represents same amount of earth space no matter where on the globe the map area is located. Although the earth is best represented by a spheroid, the earth is sometimes treated as a sphere to make mathematical calculations easier. In ms word, describe the map projections you chose. Types of map projections the number of map projections made possible is limitless, and hundreds have been published. The central focus of this book is on the theory of map projections. Among the most important cartographic considerations are map scale, coordinate systems, and map projections. The computer has also been used to evaluate and compare distortion on various map projections tobler, 1964. Understanding datums, coordinate systems and map projections. A datum provides a frame of reference for measuring locations on the surface of the earth. Lecture 2 map projections and gis coordinate systems. The final product to email will be a winzip file e. This is the winkel tripel projection, invented in 1921.
Reference systems of maps and geographic information. Some truedirection projections are also conformal, equal area, or equidistant. Map projection map projection is a letter phrase starting with m and ending with n synonyms, crossword answers and other related words for map projection. A coordinate system, datum, and map projection are. Datums, coordinate systems, coordinate reference systems. Snyder, pdf, 1997 cegis map projection bibliography usgs, database, 2011 map projections a working manual usgs pp 95, j. It is more accurite than a map with less distortion that a map has, it shows accurite shapes and sizes, and also shows accurite imformation for distances and directions between two points. Apr 25, 2017 what are the different types of map projections. Equations are furnished for map projections and datums commonly used within the army, and references are provided for other, less commonly encountered, map projections and datums. New zealand map grid nzmg has been the map projection used for general mapping. 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. This publication is a major revision of usgs bulletin 1532, which is titled map. Map projections are based on developable surfaces, and the three traditional families consist of cylinders, cones, and planes.
A map is a projection of data usually from the real earth. Creating map projections used to be a very hard thing to do. Shine a light from the center of the earth, trace the image that is projected onto the paper, and then take the paper o. 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. Maps are a twodimensional representation of a threedimensional world. Only the tm and utm projections are considered in this paper. Planar, azimuthal or zenithal projection conic projection cylindrical projection mathematical or. Datums and map projections provides clear, accessible explanations of the terminology, relationships, transformations, and computations involved in combining data from different sources. However, map projection refers specifically to a cartographic projection. 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.
A revised and expanded new edition of the definitive english work on map projections. The only accurate representation of the earth is a globe. Jan 22, 2011 the usgs has posted a scanned file of john p. 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. Today, it is usually the job of the cartographer or editor to choose a suitable map projection, taking into account the purpose of the map. The widelyused topographical maps published prior to sep 2009 use nzmg. Feb 21, 2011 equivalent or equal area projections a map areaof a given size, a circle three inches in diameter for instance, represents same amount of earth space no matter where on the globe the map area is located. Geodesy, coordinate systems, objectives and map projections. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. A map projection is the mathematical transformation of coordinates on a.
Although the earth is best represented by a spheroid. A map projection is used to portray all or part of the round earth on a flat surface. While retaining the benefits of the first edition clear presentation assuming no prior knowledge, a problemsolving approach, practical examples and the. This is a summary of map projections that have articles of their own on wikipedia or that are otherwise notable. Map projections map projections are mathematical formulas used to transfer shapes from an oval surface the earth surface more accurately, a model of it onto a flat surface. A scale tells you the ratio of a distance on the map to the actual distance in.
There are many different ways of display the geography of the world, with the robinson and mercator projections amongst the most popular. Choose from 500 different sets of quiz map projections flashcards on quizlet. To make these representations, the cartographer must calculate geographic features so that they are represented as close to real as possible. Number of pages cartography datums projections 170 geodesy coordinates 16.