Introduction to map design introduction this document is intended to help people without formal training in map design learn to produce maps for publication or electronic display using arcview, a desktop geographic information system gis. Distance, shape, direction, or size may be distorted by a projection. Cartography definition, types and elements the international cartographic association defines cartography as the discipline dealing with the conception, production, dissemination and study of maps. The purpose of this publication is to assist countries by providing a reference document that focuses on digital mapping aspect when conducting population and housing censuses.
These maps are defined by the cone constant, which dictates the angular distance between meridians. 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. The shape of the earth and the geodetic datum concept are covered on pages 46. The data for both these maps comes from the same source. These are distinguished by their different format for representing information. Comparing map projections to the globe answer key analyze the maps on the map projections handout and a globe to complete the charts below. Map projections define the spatial relationship between locations on earth and their relative locations on a flat map are mathematical expressions which transform the spherical earth to a flat map cause the distortion of one or more map properties scale, distance. Arcgis server handles reprojecting the data converting it to the requested spatial reference on the fly.
The mercator projection is one of the most common cylindrical projections, and the equator is usually its line of tangency. Imaginary lines of sight called projectors the two broad types of projections, both with several subclassifications, are parallel projection and perspective projection. Basically, however, there are three classes of map projections. Imagine a map projection as an attempt to reconstruct your face in two dimensions. Georeferencing, map projections, cartographic conceptsmap projections coordinate systemsdatum. If north or south is straight up, the aspect is said to be equatorial.
The mercator projection is a cylindrical projection that was developed for navigation purposes. This approximates the view of the earth from the sun on the winter solstice at noon in cambridge, ma. There are several types of map projections, as well as several methods used to achieve these projections. Page 79 discuss map scale and the basics of coordinate systems. What is a map projection map projection definition. We examine how to map spherical and ellipsoidal earth onto 2dimensional space, and compare two paths one can take between two points on the earth. Arcgis allows you to use thousands of different spatial references and offers many tools for working with spatial references because many governments, militaries, and other. Map projection concepts projection is a fundamental component of mapmaking map projection. The light source metaphor revisitedbringing an old. This orthographic projection of the earths surface creates a twodimensional representation of a threedimensional surface. Rather, it is the outcome of a series of highly problematic temporary settlements that divide and connect things up into different kinds of. The map may declare its sources, accuracy, publication date and authorship, and so forth.
Projections to create maps, cartographers project the round earth onto a flat surface making a map projection. The map of massachusetts in unprojected decimal degrees of longitude and latitude note the proportion of the lines and the circle. Map projections explained a beginners guide youtube. Map makers attempt to transfer the eartha round, spherical globeto flat paper. It is the only projection that can accurately represent both areas and true direction from the center of the projection. Some common examples are cones, cylinders, and planes. Globe mercator mollweide robinson lines of longitude are parallel to one another and. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane.
To use these maps, you need to know how to read a map scale and a map legend, or key. The concept of map projection yaaka digital network. Secondly, conic map projections include the equidistant conic projection, the lambert conformal conic, and albers conic. Universal transverse mercator utm utm projection is used to define horizontal, positions worldwide by dividing the surface of the earth into 6o zones, each mapped by the transverse mercator projection with a central meridian in the center of the zone. A systematic analysis of distortions in map projections notes for a course in map projections in the department of surveying engineering university of new brunswick introduction if we 1 ived on a flat earth there would be. Introduction to gis basics, data, analysis case studies. Map projections massachusetts institute of technology. The mercator projection was used for its portrayal of direction and. The example shown above is the polyconic projection, where parallels are all nonconcentric circular arcs, except for a straight equator, and the centers of these circles lie along a central axis.
A datum provides a frame of reference for measuring locations on the surface of the earth. Because maps are flat, some of the simplest projections are made onto geometric shapes that can be flattened without stretching their surfaces. When the central axis of the developable surface is oriented eastwest, the projection s aspect is. Understanding map projections landing page for kartoweb. Examples of the various types of concept maps are presented on the following pages.
It can also be defined as the transformation of spherical. Secondly, static images only provide one view on the construction process. Projection, the mental process by which people attribute to others what is in their own minds. These maps provide information about humanmade features as well as some natural features. Learn what a map projection is, why they are used and what impact they have on maps gis systems. The mercator map projection is one of the most well known cylindrical map projections. Map projection can be best visualized by imagining a light bulb. Click over each in order to open a special window that. Scale increases perpendicular to the radii toward the periphery. Map projection is the process of systematically transforming positions on the earths spherical surface to a flat. Please note though that the topic of projections is extremely broad, and this article can do no more than touch on a few important topics. Click on skip the slideshow to start your elearning session immediately.
Learning more about map projection and coordinate system concepts. Parallel projection parallel projection is a type of projection where the line of sight or projectors are parallel and are perpendicular to the. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. This paper provides an overview of the mercator 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. Some map projections preserve none of the properties described above, but instead seek a compromise that minimizes distortion of all kinds.
A spheroid with a defined origin and orientation w. This is the most profound single fact about map projections they distort the worlda fact that you will investigate in more detail in module 4, understanding and controlling distortion. The graticule of a geographic coordinate system is projected onto a cylindrical projection surface. Traditionally, the role of maps in the census has been to support enumeration and to present aggregate census results in cartographic form. Scale and symbols on maps the maps most people use are road and city maps like the ones above. A map projection is used to portray all or part of the round earth on a flat surface. For example, individuals who are in a selfcritical state, consciously or unconsciously, may think that other people are critical of them.
Map projections are introduced on pages 1012, and pages. Georeferencing, map projections, cartographic concepts. Geological survey have designed projections for their specific needs such as the space oblique. A map projection provides a way to represent the curved surface on the plane of the map. In this case, as in all cases we will deal with in this study, the projection surface is a plane. Map projection is the method of transferring the graticule of latitude and longitude on a plane surface. Handbook on geographic information systems and digital. Coordinate systems, also known as map projections, are arbitrary designations for spatial data. Map projections displaying the earth on 2 dimensional maps the world from space projection from esri, centered at 72 west and 23 south. Map projection definition of map projection by the free. It is not possible to obtain di erent views to get a comprehensive understanding of the mapping process.
We will taker a closer look at the popular mercator projection and examine how the projection. Converting a sphere to a flat surface results in distortion. The concept was introduced to psychology by the austrian psychoanalyst sigmund freud 18561939, who borrowed the word projection from neurology, where. The earths reference surface projected on a map wrapped around the globe as a cylinder produces a cylindrical map projection. A map projection systematically projects locations from the surface of a spheroid to representative positions on a flat surface using mathematical algorithms. In general, the projection surface may be another curved 3d surface and we use this general concept in the theoretical development that follows. A gis is a system for the display, analysis, storage and retrieval of information about places on the earth. The spatial or map extent covered by the dataset often referred to as the spatial domain learning more about coordinate systems here is a series of links to help you learn more about applying map projections and coordinate systems in your work. A relates distances on a map to actual distances on earths surface. Projections projections transform points in nspace to mspace, where m map points from 3space to the projection plane pp along projectors emanating from the center of projection cop. The lambert azimuthal equalarea projection is mathematically based on a plane tangent to the earth.
Kinds of concept maps there are four major categories of concept maps. If it is your first time using the course, start with part 1. 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. The importance of map projections by sarah lyle on prezi. 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. The orthographic projection distorts distance, shape, and the size of areas. As a result, the purpose of the map usually dictates which projection is used.
Map makers have devised methods for taking points on the curved surface of the earth and projecting them onto a flat surface. In looking at these two paths, we will investigate how latitude and longitude play an. Elements of map projection with applications to map and chart construction by deetz, charles henry, 1864. These methods enable map makers to control the distortion that. 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. Maps and map reading are essential skills that all of the armed forces need.
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