About map projectionthe classification of map projection. Each of the main projection typesconic, cylindrical, and planarare. Projected on a map formed into a cone gives a conical map projection. We will taker a closer look at the popular mercator projection and examine how the projection. Every projection has its own set of advantages and disadvantages. Map projections displaying the earth on 2 dimensional maps the world from space projection from esri, centered at 72 west and 23 south. The map projection is classified depending on the type of projection surface on which the globe is projected conceptually. A map projection describes how points on a plane, such as the pixels on your screen, correspond to points on the surface of the earth. In order to portray the surface of a round body on a twodimensional flat plane, you must first define a developable surface i. The definition of the map projection for projected coordinate systems.
Also concerned with the interpretation of mapped patterns. Scale increases perpendicular to the radii toward the periphery. The name of the projection is the shape that the image is projected onto. Some projections are suited for mapping large areas that are mainly northsouth in extent, others for large areas that are mainly eastwest in extent, and still others for large areas that are oblique to the equator. Other measurement system properties such as a spheroid of reference, a datum, and projection parameters like one or more standard parallels, a central meridian, and possible shifts in the x and ydirections. Manishika explains the meaning of projection, the various types of projection conical, cylindrical and planar, preservation of distortions conformal, equal area and. Types of cylindrical map projections you may know include the popular mercator projection, cassini, gausskruger, miller, behrmann, hobodyer, and gallpeters. Map projections a map projection is used to portray all or part of the round earth on a flat surface. 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. Many common map projections are classified according to the projection surface used. The three classes of map projections are cylindrical, conical and azimuthal. Projections projections transform points in nspace to mspace, where m pdf and djvu format. All map projections distort the surface in some fashion. The beginning of the book contains substantial introductory information about map projection families and distortions.
Worksheets on map projections teachers pay teachers. Because there is no limit to the number of possible map projections, there can be no comprehensive list. Map projections are often named after the cartographer who developed them, after the method used. The mapmaker must select the one best suited to the needs, reducing distortion of the most important. Map projections without distortions would represent the correct distance, direction, shapes, and areas on a map. Direction and shape are good at the equator to about latitude 40 44 n and s. Spatial thinkingwhy we use maps in geographymap projectiondistortions in map projectionsgoodes.
Map projection definition of map projection by the free. Types of maps and map projections powerpoint and worksheet. The art and science of making maps, including data compilation, layout, and design. Until a generation ago this was the ubiquitous general purpose world map.
The map user should always be aware of various types of distortions to minimize their influence on how the map is perceived. Some truedirection projections are also conformal, equal area, or equidistant. Map projections explained a beginners guide youtube. The mollweide projection is an equalarea, pseudocylindrical map projection generally used for global maps of the world or night sky.
Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. This is a summary of map projections that have articles of their own on wikipedia or that are. They then examine the distortions of different map projections while comparing land and ocean to its representation on a globe. The mercator map projection is one of the most well known cylindrical map projections. This is a summary of map projections that have articles of their own on wikipedia or that are otherwise notable. There are several map projections which preserve some of the properties of the sphere at the expense of others. A map projection is the mathematical transformation of coordinates on one surface, in our case the ellipsoidal reference surface of the earth, to coordinates on the projection plane. It is also modeled more accurately as an oblate spheroid or an ellipsoid.
Geol 3050 gis for geologists exercise 5 exercise 5. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. The conic projection is most accurate at the line where the paper touched the earth. For example, the basic mercator projection is unique. Learn what a map projection is, why they are used and what impact they have on maps gis systems. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. The lambert azimuthal equalarea projection is mathematically based on a plane tangent to the earth. Most popular world maps employ a projection that compromises among these conflicting goals. Since our original data is in a geographic coordinate system, we want to change it to a real projection. Wrap a piece of paper around the globe to form a cone. Types of map projections many types of map projections are being used for map making. There are dozens of different world map projections.
Shine a light from the center of the earth, trace the image that is projected onto the paper, and then take. Pdf the equal earth map projection is a new equalarea pseudocylindrical projection for world maps. A stone tablet found in a cave in abauntz in the navarra region of. Now it is out of favor because it greatly exaggerates. Use this lesson to teach geography classes about types of maps and map projections with great examples and an easytofollow companion worksheet. In truth, the area of map projections is highly complex and the enthusiast can easily lose themselves in many hours of reading. To change a projection, you need to first have a coordinate system defined. Ppt map projections and types powerpoint presentation. Planar, azimuthal or zenithal projection conic projection cylindrical projection mathematical or conventional projection. Its main purpose is to compute distortion grids and other types of visualizations that. Map projection a map projection is a systematic transformation of the latitudes and longitudes of locations on the surface of a sphere or an ellipsoid into locations on a plane. 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. Map projections massachusetts institute of technology. Pseudoconic projection is one of the oldest map types and although they were used by ptolemy, they are seldom seen today.
This booklet provides a conceptual introduction to. Before addressing the specific types of transformations. Types of map projections the number of map projections made possible is limitless, and hundreds have been published. Understanding map projections landing page for kartoweb. Simply, it is placing the spherical earth onto a plane flat surface. A sphere, unlike a polyhedron, cone, or cylinder, cannot be reformed into a plane. The degree and kinds of distortion vary with the projection used in making a map of a particular area. The map scale may be expressed in three ways and the pictorial representation of these three types is shown in the figure. The earths surface projected on a map wrapped around the globe as a cylinder produces the cylindrical map projection. It is the only projection that can accurately represent both areas and true direction from the center of the projection.
Equal areasa map projection is equal area if every part, as well as the whole, has the same area as the corresponding part on the earth, at the same reduced scale. This booklet provides a conceptual introduction to map projections and geographic reference systems. A tool is built on top of the interactive map projections system that provides a new method of visualizing map projection distortion. A map projection is the method to represent the spherical surface or object like that in two dimensional plane or flat surface. Secondly, conic map projections include the equidistant conic projection. In the end each and every map projection has a place, and there is no limit to the amount of projections that can be created. A map projection is a systematic transformation of the latitudes and longitudes of locations on the surface of a sphere or an ellipsoid into locations on a plane. So therefore, there are both distortion and projection. Many map projections can then be grouped by a particular developable surface. Which projection is most suitably used for which area. It is perpendicular to the direction of gravity pull. Each of the main projection types conic, cylindrical, and planarare.
Map projections and types 1 map projections and types 2 cartography. A map projection is used to portray all or part of the. Map projections are created for certain purposes and should be used for those purposes. Pdf in this paper, we introduce some known map projections from a model of the earth to a. Investigating map projections students use oranges to investigate the effects of changing a 3d surface to a 2d surface. This approximates the view of the earth from the sun on the winter solstice at noon in cambridge, ma. So in this case we added the layer with the lambert projection. The following concepts are addressed in the powerpoint. When projected on a planar map it produces an azimuthal or zenithal map projections. Although the earth is best represented by a spheroid, the earth is sometimes treated as a sphere.
Investigating map projections national geographic society. 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. Most sold by the map center use one of the following five. Learn vocabulary, terms, and more with flashcards, games, and other study tools. 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. It is also known as the babinet projection, homalographic projection, homolographic projection, and elliptical projection.
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