Shine a light from the center of the earth, trace the image that is projected onto the paper, and then take the paper o. The degree and kinds of distortion vary with the projection used in making a map of a particular area. This types of maps and maps skills pack is an asset for any teacher integrating technology in their classroom or practicing distance learning. Types of maps thematic special purpose, single topic, statistical maps. This booklet provides a conceptual introduction to map projections and geographic reference systems. In the following section on projection categories, the earth is taken as a sphere in order to simplify the discussion. It is perpendicular to the direction of gravity pull. The post1973 editions of the alaska map e more nearly approximate an equidistant conic map projection. Projections are chosen based on the needs of the map or data analysis and on the area of the world.
Although not required, you should transform your data into the. In cartography, a map projection is a way to flatten a globes surface into a plane in order to. 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. Typically, the extents are stored in a file known as world file and they have extensions like. Graphical projection has an important role in machine drawing and design.
Data management tools projections and transformations. Wrap a piece of paper around the globe to form a cone. Planar, azimuthal or zenithal projection conic projection cylindrical projection mathematical or conventional projection. Improve your knowledge of map projections in this interactive quizworksheet combo. Description of three different types of map projections. However, to maintain accuracy for largerscale maps scales of 1. Use the printable worksheet to pinpoint study points to look. A tutorial on map projections and geographic coordinate systems. Feb 21, 2011 conformal projections retain correct angular relations in transfer from globe to map. National and statelevel projectiosn of dentists and dental. Types of map projections based on developable surface one way of classifying map projections is by the type of the developable surface onto which the reference sphere is projected.
In this post we are looking forward to see the list of vector data file formats in gis. In gis, we require some data formats to express the geographical features, which mainly are of two types raster and vector data formats. 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. 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. If layers in a map have different coordinate systems defined from those of the map or local scene itself, a transformation between the coordinate systems might be necessary to.
The spatial or map extent covered by the dataset often referred to as the spatial domain learning more about coordinate systems. Pdf in this paper, we introduce some known map projections from a model of the earth to a. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. Here is a series of links to help you learn more about applying map projections and coordinate systems in your work. Because there is no limit to the number of possible map projections, there can be no comprehensive list. Map projections differ in the way they handle four. Pdf in this paper, we introduce some known map projections from a model of the earth to a flat sheet of paper or map and derive the plotting equations. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. Prerequisite skills this booklet assumes that you have completed the exercises. Selecting the right map projection is one of the important first considerations for accurate gis analysis. Map projections part of your analysis model may involve a map projection transformation. Mathematical calculations are used to convert the coordinate system used on the curved surface of earth to one for a flat surface. This is the longitude grid for southern california.
A georeference contains 2 types of information image extents and projection. The study of map projections is the characterization of these distortions. When you look at a machine, you see that the machine has planes based on parallel lines. The beginning of the book contains substantial introductory information about map projection families and distortions.
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. However, map projection refers specifically to a cartographic projection. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. Spatial data has coordinate systems, geographic coordinate systems, or projected coordinate systems defined. There are many different ways of display the geography of the world, with the robinson and mercator projections amongst the most popular.
Start studying ap human geography test 1 types of map projections. Most gis software, including qgis would be able to use information stored in the world files as long as they are stored in the same directory as the original. As an example of how it works, lets look at the entries for the british national grid mentioned in map projections. Some of the different types of map projections include cylindrical, pseudocylindrical, conic, and pseudo conical. 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. At this scale, the difference between a sphere and a spheroid is not detectable on a map. Although the earth is best represented by a spheroid. Types of map projections the number of map projections made possible is limitless, and hundreds have been published. Map projections are one of the fundamental concepts of geography and cartography.
Scale changes in one direction to be offset by scale changes in the other direction. A map projection is used to portray all or part of the round earth on a flat surface. Map projections is about presenting the round earth on a flat surface. Types of map projections portland state university. Scale same in any direction around a point, but scale changes from point to point. Projections are useful for a limited set of purposes or scales. Sep 20, 2015 description of three different types of map projections. But proper understanding of the concepts and access to the right tools will make it much easier to deal with projections. Sep 20, 2017 working with this kind of data requires some foundational information so this will cover the basics of geospatial data, then we will explore the file types, tools and programs. The gis project maintains links to the individual data files the data is not embedded in the map document itself gis formats, like shapefile shp, have many files that are linked together and must stay together in order to function descriptions of the files you create and use arccatalog. Young scholars pretend to be cartographers and specify which types of map projections would be the most valuable for their clients.
The projection that results is depicted in this image. Tobler took time to study the manuscript for the first edition, and we appreciate their suggested additions and corrections. Imagine placing the movie screen around the globe in a cylinder shape. A developable surface is a geometric shape that can be laid out into a flat surface without stretching or tearing. Dec 03, 2011 map projections are one of the fundamental concepts of geography and cartography.
Ap human geography test 1 types of map projections flashcards. Apr 25, 2017 there are many different ways of display the geography of the world, with the robinson and mercator projections amongst the most popular. Projections coordinate systems working with map projections in wms objectives learn how to wor k with projections in wms, and how to combine data from different coordinate systems into the same wms project. Ap human geography test 1 types of map projections. The map projection configuration files define the projection systems that are supported in analyzer. Geodesy, coordinate systems, objectives and map projections. Jan 22, 2011 the usgs has posted a scanned file of john p. Map projectionspdf versions of numerous projections. Introduction to geospatial data types, tools and programs. Map projections are important in creating maps with map. Use this lesson to teach geography classes about types of maps and map projections with great examples and an easytofollow companion worksheet.
Name date comparing map projections to the globe analyze the maps on the map projections handout and a globe to complete the charts below. Always a good idea to have the help box open at all times. Many common map projections are classified according to the projection surface used. The problem with projections and the reason why there are so many types is that it is very difficult to represent the curved 3d surface of the earth on a flat 2d surface of a map. Types of map projections there are three main types of map projections a. The map of massachusetts in unprojected decimal degrees of longitude and latitude note the proportion of the lines and the circle. Coordinate systems, projections, and transformations. A scale tells you the ratio of a distance on the map to the actual distance in real life. Working with this kind of data requires some foundational information so this will cover the basics of geospatial data, then we will explore the file types, tools and programs. Types of map projections many types of map projections are being used for map making. They do the globe projector activity in the xpedition hall and take notes on the different map projections. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane.
Finally, projections are based on local needs and standards. 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. This topic shows how to use the map function to view projections, and how to warp a map image to a map projection. In this paper, we introduce some known map projections from a model of the earth to a flat sheet of paper or map and derive the plotting equations for these projections. 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. Spatial thinkingwhy we use maps in geography map projectiondistortions in map projections goodes. Map projections or coordinate reference system crs often cause a lot of frustration when working with gis data. Notice that areas close to the equator have very little distortion. Some analysis tools that involve distance or area calculations will require your data to be in a projected coordinate system. Likewise, frequently used projections can be saved by rightclicking on the projection and selecting add to favorites which will then show the projection under the favorite projections folder. Various types of projection can be used to understand a 3d structure. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Geol 3050 gis for geologists exercise 5 exercise 5.
The alaska map e was adapted from a set of transverse mercator projections 8 wide and approximately 18 long, repeated east and west of an arbitrary point of origin until a projection 72 wide was obtained. Large areas tend to look more like they do on the globe than is true for. The following concepts are addressed in the powerpoint. Prerequisite tutorials introduction to wms required components gis map time 1525 minutes v. 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. These data sources also has multiple file formats in them which are often used to express the geographical features. Just like there are many geographic coordinate systems, there are many different map projections as welleach preserves the spatial properties of data shape, area, distance, and direction differently. Map projections cylindrical projection a cylindrical projection map is the most common type of map that we see. Map projections coach grigg ap human geography golf. Oct 01, 2015 types of map projections many types of map projections are being used for map making. Map projections a map projection is a set of rules for transforming features from the threedimensional earth onto a twodimensional display. Each of the main projection typesconic, cylindrical, and planarare.
Map projections are a systematic transformation of longitudes and latitudes of a location on the surface of the sphere. National and statelevel projections of dentists and dental hygienists in the u. The projection parameters these depend on the locality. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Shine a light from the center of the earth, trace the image that is projected onto the paper, and then take. No flat representation of the earth can be completely accurate, so many different projections have been developed, each suited to a particular purpose. Projections a projection is the means by which you display the coordinate system and your data on a flat surface, such as a piece of paper or a digital screen. Here we discuss the important types of projections, including their advantages and disadvantages. Idls map function allows you to view more than 30 different map projections. The problem with projections and the reason why there are so many types is that it is very difficult to represent the curved 3d surface of the earth on a.
Cylindrical wrap a piece of paper around the earth to form a cylinder that touches the equater all the way around the earth. Maps were devised because they are much easier to use, store, and transport than globes, and they facilitated the development of much larger. Name the coordinate systems of the files that are plotting on top of each other. 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. A map projection is used to convert data from a geographic coordinate system to a projected planar coordinate system. Between those scales, choosing to use a sphere or spheroid will depend on. Worksheets on map projections teachers pay teachers. Teaching map skills and how to read different types of maps is an essential skill that spans across many grade levels. 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. This is a summary of map projections that have articles of their own on wikipedia or that are otherwise notable. Understanding map projections landing page for kartoweb. Except where otherwise noted, images on this site are by tobias jung and are licensed under cc bysa 4. National and statelevel projectiosn of dentists and. The conic projection is most accurate at the line where the paper touched the earth.
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