Dec 03, 2011 common map projections what are some common map projections and what agencies use them. Coordinate systems either geographic or projected provide a framework for defining realworld locations. Implicit with any gis data is a spatial reference system. Some basic ideas about the mathematics of map projections. Download the list of supported geographic and vertical coordinate systems. A datum is a specific, known point on or in the earth that is used for reference. Understanding coordinate systems and projections for arcgis 1. A coordinate is a set of two or more numbers that specifies the position of a point, line, or other geometric figure in relation to some reference system. This book explains in a clear and complete manner the terms and concepts of map projections and how they can be applied to your data.
Intro to coordinate systems and utm projection youtube. A projected or planimetric coordinate system that maps locations on the. The map of massachusetts in unprojected decimal degrees of longitude and latitude note the proportion of the lines and the circle. Understanding coordinate systems and map projections. Projected coordinate systems, map projections, parameters, and linear units of measure current as of arcgis version 9. Presented by john schaeffer juniper gis services, inc. This handbook provides methods and parameter values to shift positions between many geodetic datums and provides methods for converting between geodetic coordinates, cartesian coordinates, and map projection coordinates. However, if you want to make sure that all of the data you are using in a project has the same coordinate system for consistency and accuracy in analysis and editing, or to minimize. Handbook on geographic information systems and digital. This short book starts with an overview of geographic and projected coordinate systems then discusses geographic transformations. Knowledge of scale factors is fundamental in understanding map projections and. A gcs includes an angular unit of measure, a prime meridian, and a datum based on a. Understanding and using geometry, projections, and spatial reference systems in arcgis author. The shape of the earth and the geodetic datum concept are covered on pages 46.
If layers in a map have different coordinate systems defined from those of the map or local scene itself, a transformation between the. Types of coordinate systems there are two common types of coordinate systems used in gis. Coordinate systems, projections, and transformationsproperties of. This powerpoint is available at gis linkspresentations understanding coordinate systems for arcgis 2. 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.
A tutorial on map projections and geographic coordinate systems. In short, a projection is used to flatten the ellipsoidal shape of the earth to rectangular coordinate system e. Page 79 discuss map scale and the basics of coordinate systems. Each position has two values that reference it to that central location. Understanding coordinate systems and projections for. Understanding projections and coordinate systems important knowledge to have, especially if you deal with many different sets of data that come from different sources. Understanding coordinate management in the geodatabase. Chapter 9 coordinate systems intro to gis and spatial. Map projections are introduced on pages 1012, and pages. Articulate the leader in rapid elearning and communications. Map projections, a working manual, usgs professional paper.
Coordinate systems and map projections 2nd edition. 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. Understanding difference between coordinate system and. Geographic coordinate systems are based on a spheroid and utilize angular units degrees.
Coordinate systems, projections, and transformations. Certification of completion esr certifies that has successfully completed the esr e sri training and education mtraining. Conceptual summary of projections aa coo d ate syste sn coordinate systems xy coordinates derived via projection from latlong t iti 2 dfl t lines of latitude and longituderepresent position on 2d flat map surface spheroid. Coordinate systems, map projections, and geographic datum. Purchase coordinate systems and map projections 2nd edition. 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. 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 coordinate system is a reference framework that defines the position of features in either two or threedimensional space. Lecture 2 map projections and gis coordinate systems. Coordinate systems the nature of geographic information.
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. In a projected coordinate system, locations are identified by x,y coordinates on a grid, with the origin at the center of the grid. 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. Each geometric approach is called a map projection, since it. Understanding map projections introduces and illustrates what geographic and projected coordinate systems are and the elements that make up each.
Whats the difference between a projection and a datum. Understanding and using geometry, projections, and spatial. A projected coordinate system based on a map projection such as transverse mercator, albers equal area, or robinson, all of which along with numerous other map projection models provide various mechanisms to project maps of the earths spherical surface onto a twodimensional cartesian coordinate plane. Understanding coordinate systems and projections for arcgis. The appearance, classification and naming of map projections. Overview of projections and coordinate systems classifying. In arcgis, the coordinate system is used as the method to automatically integrate the geographic locations from different datasets into a common coordinate. Coordinate systems can be horizontal, defining where features are across the globe, or vertical, defining how high or deep features are relative to a surface. Specify a coordinate systemproperties of maps arcgis pro. A clear understanding of the different coordinate systems and datums in use today and the appropriate transformations between these is therefore essential to ensure rigorous consideration of. Projected coordinate systems it also referred to as rectangular coordinate systems such as planar, cartesian, and grid coordinate system it converts earths curved surface onto a flat map surface the x value is given first and called easting, then the y value is given and called northing 35 36.
Coordinate systems can be defined in both maps and scenes. The employed plane coordinate system is either projected or geographic. There are plenty of datasets that do not include such machine readable metadata. Understanding coordinate systems and projections for arcgis duration. 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. State plane coordinate system fips, zones and the fifty states, learn all about. Oct 08, 20 presentation objectives understand basic concepts on coordinate systems for the gis user. Do all your shapefiles have to be a projected coordinate. A projected coordinate system based on a map projection such as transverse mercator, albers equal area, or robinson, all of which along with numerous other map projection models provide various mechanisms to project maps. This chapter introduces geodesy, the science of measuring the shape of the earth, and map projections, the transforma. 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.
Understanding datums, coordinate systems and map projections. These are often referred to arcgis 10 what are map projections. Geographic and projected coordinate systems keys to. Government acquire greater than restrictedlimited rights.
Join adam wilbert for an indepth discussion in this video understanding projection and coordinate systems, part of learning arcgis. Handbook for transformation of datums, projections, grids qe51ud01 and common coordinate systems 6. The geometry of the earth has been discussed, studied, and imagined forever. Projections transformation of curved earth to a flat map.
Army topographic engineer center report number 7701 telegraph road tecsr7 alexandria, va 223153864 9. 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. It can consist of a simple arbitrary reference system such as a 10 m x 10 m sampling grid in a wood lot or, the boundaries of a soccer field or, it can consist of a geographic reference system, i. The difference is that wgs 84 is a geographic coordinate system, and utm is a projected coordinate system. Understanding projection and coordinate systems linkedin. Conceptual summary of projections aa coo d ate syste sn coordinate systems xy coordinatesderived via projection from latlong t iti 2 dfl t lines of latitude and longituderepresent position on 2d flat map surface spheroid. Maps and scenes use coordinate systems to locate and display data correctly on the earths surface and relative to one another.
The drawing at the bottom of figure 339 shows lines estimating approximately equal scale distor tion for a transverse mercator projection centered on the usa. Understanding and using geometry, projections and spatial reference systems in arcgis. Spatial data can also be expressed using projected coordinate systems pcs. Datums, coordinate systems, coordinate reference systems. Understanding and using geometry, projections, and spatial reference systems in arcgis. From the perspective of a geographic software design three coordinate systems can potentially be addressed. 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. Presentation objectives understand basic concepts on coordinate systems for the gis user. 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. Projected coordinate systems are based on a plane the spheroid projected onto a 2d surface and utilize linear units feet, meters, etc. The course format includes detailed information on how these concepts are applied to different regions of the pacific islands. So we should get used to understanding map projections and their properties. Join adam wilbert for an indepth discussion in this video, understanding projection and coordinate systems, part of arcgis essential training. In order to properly display, interpret, analyze, and combine spatial data sets, every.
Spatial data has coordinate systems, geographic coordinate systems, or projected coordinate systems defined. Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles, and areas across the two dimensions. This includes cad data and data and shape files created with arcmap before 2002. Join adam wilbert for an indepth discussion in this video, understanding projection and coordinate systems, part of learning arcgis. Understanding difference between coordinate system and projection. Geographic and projected coordinate systems keys to creating and understanding maps.
The gcs tells your data where to draw on the earth, and the projection tells the map how to distort the earth onto a flat surface. Working with map projections and coordinate systems in arcgis. Understanding map projections and coordinate systems 18 course hours january 7, 2011. A working manual available online scanned file from the usgs of john p. The remaining half of the book presents attributes of over sixty supported map projections in arcgis. Projected coordinate systems are derived from map projections and geographic coordinate systems from latitude and longitude degrees. A global or spherical coordinate system such as latitudelongitude. This selfpaced, online training teaches the fundamental concepts of map projections, datums, and coordinate systems and demonstrates how to use them using esris arcgis.
Gis works with spatial data, and, with using this data that needs to be placed at locations. The state grids have been merged into countrywide grids. Coordinate systems enable geographic datasets to use common locations for integration. Ellipsoidal coordinate systems reference a mathematically derived spheroidal or ellipsoidal volumetric surface. The definition of the map projection for projected coordinate systems. Working with map projections and coordinate systems in. Understanding map projections, datums, and coordinate systems. A gcs is often incorrectly called a datum, but a datum is only one part of a gcs. Coordinate systems are referenced to the physical earth surface through the use of datums. Each differ either in the order of the coordinate tuple or in the direction of increasing values. Map projections and coordinate systems gis courses.
Coordinate systems enable you to integrate datasets within maps as. Learning the basic properties and uses of coordinate systems understanding the difference between geographic coordinates and projected coordinates getting familiar with different types of map projections managing and troubleshooting coordinate systems of feature classes and images. Join adam wilbert for an indepth discussion in this video understanding projection and coordinate systems, part of arcgis essential training. Datums, projections, and coordinate systems us fish and wildlife. In this third module, were going to start off with talking all about projections.
The techniques for combining two source projections to. You will need to understand the building blocks of how to define and visualize a location. A map projection is simply a method for converting, or projecting, the threedimensional surface of. A projected coordinate system is always based on a geographic coordinate system that is based on a sphere or spheroid. Projected coordinate systems are sometimes referred to as map projections. The objective of this section is to describe and discuss the concepts of map scale, coordinate systems, and map projections and explain why they are central to maps, mapping, and geographic information systems giss. Handbook for transformation of datums, projections, grids. It is extremely important that you gain an understanding of coordinate systems and map projections. The goal was to merge dissolve these shapefiles of burn area for this time frame and calculate the. Question asked by mctraverso on may 22, 2017 latest reply on jun 2. A projected coordinate system is defined on a flat, twodimensional surface. Intro to coordinate systems and utm projection middlebury remote sensing. The ancient greek philosophers tried to picture a pure geometrical model.
Do all your shapefiles have to be a projected coordinate system in order to calculate geometry. A coordinate system defines where a particular location is on the map or specifies. Lab 3 understanding coordinate systems and map projections 662014 page 5 of 28 3. Heres the recipe for a projected coordinate system.
1080 717 911 1346 266 534 379 639 45 1208 1290 1213 731 916 319 1054 1304 10 265 1249 853 1324 1372 538 254 432 149 1089 1468 708 543 1439 1534 849 42 1071 898 188 714 1360 1337 593 1428 1075 572 1431 430 1087 951 40 419