Importance of map projection pdf

Road distance map of the united states student drawing. Map elements are the title, map body, map border, legend, scale, north arrow and the acknowledgement. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. As these terms have a significance meaning and importance while georeferencing how we will see down the line. A projection is a way of keeping the distortion of a flat map. The second chapter discusses, inter alia, costbenefit analysis of an investment in digital cartography and gis, plans for census cartographic process, digital map database development, quality assurance, database maintenance, and use of gis during census enumeration. Each projection preserves, compromises, or approximates basic metric properties in different ways. Map production means arranging map elements on a sheet of paper. Learn what a map projection is, why they are used and what impact they have on maps gis systems. It is thanks to the coordinates that we can create overlays in a gis and perform analyses that incorporate data from more than one.

The ellipses show how imaginary circles on the globe are deformed because of a particular. All projections involve some degree of distortion, and those showing the entire earth involve a large degree. Maps and map reading are essential skills that all of the armed forces need. What is the importance of map projection in geographic. Types of map projections the number of map projections made possible is limitless, and hundreds have been published. But until modern times, the map was printed as a document. In section 2 we examine one type of map construction. Overview, classi cation and selection of map projections for geospatial applications resulting in a disastrous map, there by deval uating the message the map attempts to communicate. 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. Pseudoconic projection is one of the oldest map types and although they were used by ptolemy, they are seldom seen today. An orthographic projection map is a map projection of cartography.

In reality once you decided which projection you are going to work with, to have all your data with the same projection or to transform data that is in another projection is very simple. The importance of map projections by sarah lyle on prezi. This is because two major data distributors distribute their data in these projections. Lecture 2 map projections and gis coordinate systems.

A sphere, unlike a polyhedron, cone, or cylinder, cannot be reformed into a plane. A gis without coordinates would simply be a database like microsoft excel or access. These maps will focus on an important location as their central point and use an appropriate. The mapmaker must select the one best suited to the needs, reducing distortion of the most important features. No projection allows us to flatten the globe without distorting it. Map projections distortions projection refers to the notion of shining light through the earth surface and projecting latitudes, longitudes and geographic features onto a developable surface. In case we want to draw a map of the world on paper, we need to exploit and apply a given projectio. It is the only projection that can accurately represent both areas and true direction from the center of the projection.

The importance of the map projection has long been recognized in large scale mapping and in analytical and mathematical cartography. The lambert azimuthal equalarea projection is mathematically based on a plane tangent to the earth. The mapmaker must select the one best suited to the needs, reducing distortion of the most important. The circle gives the impression that worcester is approximately the same distance from boston as new hampshire, and that the state is nearly five times longer, east to west, as it is northtosouth. A map projection without distortions would correctly represent shapes, angles. The various features shown on a map are represented by conventional signs or symbols. In order to portray the surface of a round body on a twodimensional flat plane, you must first define a developable surface i. Geospatial users have a wide variety of projections too choose from. While the peters projection map is superior in its portrayal of proportions and sizes, its importance goes far beyond questions of cartographic accuracy it challenges our view of the world. This process is typically, but not necessarily, a mathematical procedure some methods are graphically based. Dec 19, 20 before i move to georeferencing, i would like to explain few geospatial terminologies like spatial data, coordinate system, datum and map projection.

Map projection study guide by smayk includes 14 questions covering vocabulary, terms and more. Apr 25, 2017 pseudoconic projection is one of the oldest map types and although they were used by ptolemy, they are seldom seen today. The point of perspective for the orthographic projection is at infinite distance. Pdf a projection aspect is usually defined in references as the relation to the so called auxiliary surface. Measures of latitude and longitude expressed in degrees, minutes and seconds cannot be used as a distance measure.

Compare it with the following map made with a mollweide projection. The concept of map projection yaaka digital network. The last few decades have seen numerous attempts to create automated map projection selection. For example, colors can be used to indicate a classification. Every projection has its own set of advantages and disadvantages. Generally the azimuthal equidistant map projection portrays less than one. Distortion ellipses help us to visualize what type of distortion a map projection has caused, how much distortion occurred, and where it occurred. Many other projections are used, for example, the conic projection, drawn from a point directly above the north or south pole. 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. The next map is an azimuthal map projection with all places shown at their correct direction from seattle. A map projection is one of many methods used to represent the 3dimensional surface of the earth or other round body on a 2dimensional plane in cartography mapmaking. Vice versa, an areapreserving projection can not be conformal, resulting in shapes and bearings distorted in most places of the map.

Scale represents the ratio of a distance on the map to the actual distance in the real world. Therefore we must use a projection and none are really true to the actual spherical location. It is important for a gis analyst to have a thorough understanding of map projections and coordinate systems. Invented in the 16th century, the projection is that of the sphere on a cylinder tangent to the equator. The surface of a sphere cannot be represented as a flat map. As shown below, some states are covered with a single zone while others are divided into multiple zones. The importance of this map is that it is conformal.

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. For example, the basic mercator projection is unique. This booklet provides a conceptual introduction to map projections and geographic reference systems. The importance of horizontal and vertical datums in. Jan 06, 2017 learn what a map projection is, why they are used and what impact they have on maps gis systems. Pdf overview, classification and selection of map projections for. Generally speaking, a datum is a base value to which all other values relate. Each zone is based upon a unique map projection that minimizes distortion in that zone to 1 part in 10,000 or. Which projection to use depends on the purpose of the map. The map of massachusetts in unprojected decimal degrees of longitude and latitude note the proportion of the lines and the circle.

The albers projection is an example of a conic map projection. Map projections help us to transform and project the shape of the earth from one form to another. The mercator projection is still widely used, especially when northsouth dimensions are of chief importance. Scale is displayed in map units meters, feet or degrees. Mercator projection with norway relegated to the top, to a polarcentric projection which gave a better image of norway. Map projections a map projection is used to portray all or part of the round earth on a flat surface. Because earth has a curving, notquite sphericial shape, planar maps of. Handbook on geographic information systems and digital mapping. The azimuthal map projection is angular given three points on a map a, b, and c the azimuth from point b to point c dictates the angle someone would have to look or travel in order to get to a. Map projections essaysmap projection can be defined as the spatial relationship between features on the earths surface and their representation on a flat map. A tutorial on map projections and geographic coordinate systems. The resulting map projection illustrates the distortion introduced by the road system.

The importance of map projection in world map teaching at. Dec 27, 2002 a map projection is one of many methods used to represent the 3dimensional surface of the earth or other round body on a 2dimensional plane in cartography mapmaking. They can also be used to mark a location where valuables have been left, as. When projected directly onto the mapping plane it produces an azimuthal or zenithal or planar map projection. Both projections are appropriate based on the distributors interests. Projected on a map formed into a cone gives a conical map projection. The peters map, the work of the german historian arno peters, provides a helpful corrective to the distortions of traditional maps. Before i move to georeferencing, i would like to explain few geospatial terminologies like spatial data, coordinate system, datum and map projection. If you thought that our discussion of map projections in class was merely academic, the following series of steps should drive home the fact that a failure to understand the projection of a map can lead to a very major blunder. Look at the relative sizes of africa and greenland in both maps.

You could say that the distance from london to moscow, idaho is 117 degrees and 1 minute, however this would be. 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. While the peters projection map is superior in its portrayal of proportions and sizes, its importance goes far beyond questions of cartographic accuracy. There are many ways to apportion the distortion, and so there are many map projections. Today i was explaining somebody about the consequences of messing up the geographic coordinate systems and projection when you are working with gis data. Sep 03, 20 the world is globe shaped, a map is flat. It is perpendicular to the direction of gravity pull. This compares and transforms the earths 3d terrain to a flat 2d surface. Anaximander, eratosthenes, apolonious and hipparchus played an important role in the development of cartography. We will taker a closer look at the popular mercator projection and examine how the.

The mercator projection was used for its portrayal of direction and shape, so it was helpful to the sailors of that time. A map represents the horizontal projection of the area surveyed and not the actual area. Like the stereographic projection and gnomonic projection, orthographic projection is a perspective or azimuthal projection, in which the sphere is projected onto a tangent plane or secant plane. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. Although the earth is best represented by a spheroid, the earth is sometimes treated as a sphere. Surveying also includes the technique of establishing points by predetermined angular and linear measurements. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. Because degrees of latitude and longitude dont have a standard length, you cant measure distances or areas accurately or display the data easily on a flat map or computer screen.

From the plans, sections, and maps prepared by surveying, the area and volume of a particular plot of land can be calculated. Scale increases perpendicular to the radii toward the periphery. The di culty was deciding not only how to map from 3dimensions to 2dimensions but also deciding which way was most e ective and useful. Peters projection map, widely used in educational and.

Map was drew on the paper or other material sheepskin upper roads, settlements and natural elements, etc. The state plane projection is the best overall projection for massachusetts. A map projection is a geometric function that transforms the earths curved, ellipsoidal surface onto a flat, 2dimensional plane. Map projection definition of map projection by the free. Although the earth is best represented by a spheroid, the earth is sometimes treated as a sphere to make mathematical calculations easier. The scale of a map on any projection is always important and often crucial to the maps usefulness for a given purpose. Map projection pdf importance of map projection uses of map projection conic map projection cylindrical map projection azimuthally map projection. In the process of projection the earth is represented by a model an ellipsoid. 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. Mar 21, 2011 today i was explaining somebody about the consequences of messing up the geographic coordinate systems and projection when you are working with gis data. The mercator projection is a cylindrical projection that was developed for navigation purposes. We will taker a closer look at the popular mercator projection and examine how the projection.

This booklet provides a conceptual introduction to. Handbook on geographic information systems and digital. With an accurate map, however, travelers can get to their destinations in the safest and fastest way possible. Armed forces military maps show the earth drawn to scale as you would see it from above the military uses the universal transverse mercator utm and the universal polar stereographic ups grid system.

These maps had to be created by hand at first and were made during long and tedious journeys. The importance of the correct use of projections in gis data. A map projection is a mathematical transformation of a sphere earth to a flat surface map. Take a look at the following map of the world, made using the well known mercator projection. A map is a visual representation of an entire area or a part. Scale distortions on map projections map projections without distortions would represent the correct distance, direction, shapes, and areas on a map. We refer to them often while we travel or have used them in schools and in our daily lives for information, but what exactly is a map.

Understanding this, you will agree that a map intended to be used for interpreting shapes and directions should. The importance of map human use map already has a very long history. Datums to be usable, for example in a gis environment, a coordinate value referencing a position on the earths surface needs to be tied to a datum. Map projections explained a beginners guide youtube.