Whenever you make a map, youre abstractinginformation about the real world and placing iton to a flat plane such as a computer screen or a piece of paper. A practical guide to coordinate reference systems, datums and map projections. Learn the latest gis technology through free live training seminars, selfpaced courses, or classes taught by esri experts. This is a difficult process, but at least you can choose what coordinate system to use. Learn about geographic coordinate systems and map projections and how to work with them in arcgis pro. Working with map projections and coordinate systems in. Buy coordinate systems and map projections, second edition on free shipping on qualified orders. Sep 15, 2017 working with map projections and coordinate systems in arcgis duration. The most critical issue in dealing with map projections is knowing what the projection is and having the correct coordinate system information associated with a dataset. The earth exists in threedimensions but, other than globes, most representations of the earth, such as maps, are two dimensional. Map projections and coordinate systems gis courses. I set the projection of arcmap dataframe to projected coordinate system web mercator and changed the display values from meters to decimal degrees. Spatial data has coordinate systems, geographic coordinate systems, or projected coordinate systems defined.
The earth has a circumference of around 24,900 miles, but is around 27 miles wider than it is tall. This projection is based on the mathematics of a cone intersecting a sphere. Projections and coordinate systems may seem complex and arcane to you, but as you become more familiar with gis and gis datasets, you will become more capable of handling different coordinate systems and projections. As described under map projections, traditional coordinate systems are based on a flat coordinate system. This lectures a quick overview of what projections and coordinate systems are. Identifying coordinate system of shapefile when unknown. Map projections are the means by which data about the 3. There are many different coordinate systems, based on a variety of geodetic datums, projections, and units in use geographic coordinate systems no projection. Coordinate systems and map projections 2nd edition. A map projection is a geometric function that transforms the earths curved.
Within or on top of the projection is a coordinate system containing the x and y location values, which incorporates the ellipsoid shape of the earth, datum known base values, and units e. The process of converting a threedimensional space to a twodimensional map is called projection. The revisions take into account the huge advances in geometrical geodesy which have occurred since the early. Select a suitable map projection or coordinate system summary. Work undertaken in the usa and ussr on the creation of suitable map projections obtained through numerical analysis has been included. Purchase coordinate systems and map projections 2nd edition. Map projections and coordinate systems clarke major. This pdf file lists map projections supported in arcgis desktop version 10. Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles, and areas across the two dimensions. The course format includes detailed information on how these concepts are applied to different regions of the pacific islands. How is the 3d surface of the earth modeled onto a 2d surface. There are several ways to refer to a coordinate system. Understanding coordinate systems and projections for arcgis duration. In this third module, were going to start off with talking all about projections.
When we use the term map projection, were referring to the relationship between the rows and columns of data in the 3d grid to the latitudelongitude of the earth. Types of coordinate systems there are two common types of coordinate systems used in gis. Gis positional data are primarily printed maps which have been digitized. Geographic coordinates, latitude and longitude, are in fact not considered projected. Though it displays latlon values, i think it is projected coordinate system. Map projections are introduced on pages 1012, and pages.
A global or spherical coordinate system such as latitudelongitude. 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. D surface of the earth and its features are transformed onto a flat plane for the. D h maling a revised and expanded new edition of the definitive english work on map projections.
Understanding projections and coordinate systems important knowledge to have, especially if you deal with many different sets of data that come from different sources. Gis data differs from other data types, primarily because it contains geographic coordinates describing the location of the data on the earth. Commonly used coordinate systems can be exported to a favorites folder. May 02, 2011 working with map projections and coordinate systems in arcgis. Nearly all projections are applied via exact or iterated mathematical formulas that convert between geographic latitude and longitude and projected x an y. Join adam wilbert for an indepth discussion in this video understanding projection and coordinate systems, part of learning arcgis. The physical location of this folder is the application data\esri\desktop10. Commonly used projections and coordinate systems in bc are utm and bc albers. Select a suitable map projection or coordinate system. Theres something wrong with your datas coordinate system, but what to do.
A projected coordinate system is always based on a geographic coordinate system that is based on a sphere or spheroid. Mar 16, 2015 there are many different coordinate systems, based on a variety of geodetic datums, projections, and units in use geographic coordinate systems no projection. Terminology what all those words really mean geodesy the shape of the earth geographic coordinate systems datums map projections projected coordinate systems working with projections in arcgis understanding coordinate systems for arcgis 3. This type of figure is termed an oblate ellipsoid or spheroid, and is the threedimensional shape. These are measures of the angles in degrees from the center of the earth to a point on the earths surface when the earth is modeled as a sphere. Pdf reference surfaces, coordinate systems and projections are the prerequisites for the geospatial analysis of planetary surfaces. Gallery of map projections pdf versions of numerous projections. Introduction to coordinate systems and projections fondren. Understanding projections and coordinate systems important knowledge to have, especially if you deal with many different sets of. Projected coordinate systems indicate where something is on a map or other representation of the surface of the planet while we live in a threedimensional world, our experience of and interaction with the world at human scale is often perceived of and represented in two dimensions. Where is the coordinate systems folder, and where are the projection files at arcgis for desktop 10.
Pdf map projections in planetary cartography researchgate. Ellipsoidal coordinate systems reference a mathematically derived spheroidal or ellipsoidal volumetric surface. Maling gis applications spring 2004 objectives malings assumption. Projected coordinate systems, map projections, parameters, and linear units of measure current as of arcgis version 9. Oct 08, 20 presentation objectives understand basic concepts on coordinate systems for the gis user. Exploring map projections created using d3, map projection transitions provides an excellent way to visualize a wide range of map projections. Map projection, coordinate system and datum youtube. Presentation objectives understand basic concepts on coordinate systems for the gis user. And projected coordinate systems that sacrifice some specificity, but built on top of those geographic coordinate systems, so that we can display and analyze.
Gis needs to be able to register data from different. These show up as distortions of area, shape, direction, distance, and scale. Projected coordinate systems a map projection is the systematic transformation of locations on the earth latitudelongitude to planar coordinates the basis for this transformation is the geographic coordinate system which references a datum map projections are designed for specific purposes. Projections and coordinate systems using corpscon, the projector. Coordinate systems and map projections, second edition. Coordinate systems, map projections, and geographic datum.
And many gps users never consider that there may be other coordinate system that would better meet their needs. Some basic ideas about the mathematics of map projections. Introduction to coordinate systems and projections. The basic concepts behind map projections explained. The geometry of the earth has been discussed, studied, and imagined forever. 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. The earth is a spheroid it is round like a ball or sphere but flattened by slightly by the centrifugal force of rotation. Although for many mapping applications the earth can be assumed to be a perfect sphere, there is a difference between the distance around the earth between the poles versus the equator. Dana, department of geography, the university of texas at austin, and were developed as part of the geographers craft project at the university of texas at austin. Understanding coordinate systems and projections for arcgis. The earth exists in threedimensions but, other than globes, most representations of the earth are two dimensional. A map projection is the mathematical process of taking a view of a spherical globe and drawing that information on a flat piece of paper. If youve taking the specialization with us, you may recall that we discussed this in the first course, but this will be an indepth, more technical overview of projections and coordinate systems.
With a smallscale map, your choice of map projection determines the overall appearance of the map. 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 ensure data lines up correctly. Projections transformation of curved earth to a flat map. The book concludes with a chapter on the abuse and misrepresentation of map. No matter how you try, the resulting maps always have distortions. The appearance, classification and naming of map projections. Coordinate systems and map projections ebook, 1992. Under related information below, click the link titled projections table 2009 to access. This is changing somewhat as more data are collected by gps. A map projection is the mathematical transformation of the earth to a flat surface.
For remote sensing, gis and surveying has become a key book for many students and professionals around the world. A revised and expanded new edition of the definitive english work on map projections. Extension in arcview, and project in arcinfo marylands stateplane coordinate system is based on a lambert conformal conic projection. Spheroid or ellipsoid based systems, local systems. Coordinate systems enable geographic datasets to use common locations for integration. In the first extension we introduce optimal map projections by variational. Most gps receivers come out of the box set to use latitudelongitude coordinates.
Nov 14, 2019 to select a map projection, determine which of the properties is the most important for the project, and select the coordinate system or map projection that best preserves that property. 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. Since the planet earth isnt flat, some distortions ofthe data will inevitably occur during the transformation process. The circumference of the earth is about 0th smaller around the poles. This article applies to only arcgis for desktop versions 10. Geographic and projected coordinate systems keys to creating and understanding maps. Resources are available for professionals, educators, and students. We introduce the mapping from a left riemann manifold to a right one specified. Projections and coordinate system linkedin slideshare.
You can add coordinate references by either comparing known features with another map that has coordinate information or by locating several know point in the field and surveying them with your gps receiver. Where is the coordinate systems folder, and where are. While retaining the benefits of the first edition clear presentation assuming no prior knowledge, a problemsolving approach, practical examples and the combination of gpsderived data from other. Projections and coordinate systems are a complicated topic in gis, but they form the basis for how a gis can store, analyze, and display spatial data.
Analytical derivation of some map projections including examples of pseudocylindrical and polyconic projections is also covered. 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. Coordinate systems, on the other hand, are how we locate a point on. The signs of x,y coordinates in a projected coordinate system. Working with map projections and coordinate systems in arcgis duration. Some people casually refer to any coordinate system as a projection, but this is not strictly true.
The figures on this page are the intellectual property of peter h. Any planar coordinate system is based on a map projection, which is the orderly transfer of positions or places on the surface of the earth to c orresponding points on a twodimensional surface, like a sheet of paper. A geographic coordinate system is a method for describing the position of a geographic location on the earths surface using spherical measures of latitude and longitude. Intro to coordinate systems and utm projection duration. The revisions take into account the huge advances in geometrical geodes, isbn 9780080372341 buy the coordinate systems and map projections ebook. Each method of map projections are based on different equations and different spheres or spheroids, in order to serve different purposes. Working with map projections and coordinate systems in arcgis. A projected coordinate system is defined on a flat, twodimensional surface. Coordinate systems and map projections 2nd edition elsevier. The process of projection involves distorition of area, distance, shape, and angles. Map projections cartographic information systems erik w.
Various map projections try to minimize the distortions,but no projection can eliminate all distortions at once. Sep 20, 2019 this selfpaced, online training teaches the fundamental concepts of map projections, datums, and coordinate systems and demonstrates how to use them using esris arcgis. While retaining the benefits of the first edition clear presentation assuming no prior knowledge, a problemsolving approach, practical examples and. Download the list of supported geographic and vertical coordinate systems. For example, with some projections, lines of latitude and longitude will appear curved. Overview of projections and coordinate systems classifying. Coordinate systems, projections, and transformations. The shape of the earth and the geodetic datum concept are covered on pages 46. We talked about geographic coordinate systems that tie everything back to our spherical model of the earth. Arcgis pro and arcmap will projectonthefly to make your data draw with whatever coordinate system your map is using, and it will draw in the right place. Most coordinate systems used on the earth consist of two. Geographic and projected coordinate systems keys to. Understanding map projections, datums, and coordinate systems.