Some basic ideas about the mathematics of map projections. Introduction to coordinate systems and projections. Map projection calculations are complicated elevation is always handled separately anyway benefits ecef is scalable from small to big and viceversa straight forward computation between two 3d cartesian coordinate systems the conversion is conformal ecef to topocentric is valid for any celestial body. An ellipsoid or sphere together with its position relative to the centre of the earth defines a datum.
Geodesy, coordinate systems, objectives and map projections. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. A datum is a set of parameters defining a coordinate system. Your organization mandates using a particular projected coordinate system for all maps. Projected coordinate systems are derived from map projections and geographic coordinate systems from latitude and longitude degrees. Projected coordinate systems, map projections, parameters, and linear units of measure. On smallscale maps, where a small distance on the map represents a considerable distance on the earth, distortion may have a bigger impact, especially if you use your map to compare or measure shape, area, or distance.
Spatial data has coordinate systems, geographic coordinate systems, or projected coordinate systems defined. For example, with some projections, lines of latitude and longitude will appear curved. Some people casually refer to any coordinate system as a projection, but this is not strictly true. Datums tell us the latitudes and longi tudes of features on an ellipsoid. Projections transformation of curved earth to a flat map. The course format includes detailed information on how these concepts are applied to different regions of the pacific islands. Geographic and vertical coordinate system tables note. A gcs includes an angular unit of measure, a prime meridian, and a datum based on a. The basis for this transformation is the geographic coordinate system which references a datum map projections are designed for specific purposes. The definition of the map projection for projected coordinate systems. Lecture 2 map projections and gis coordinate systems. 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.
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. Only the tm and utm projections are considered in this paper. Learn about geographic coordinate systems and map projections and how to work with them in arcgis pro. Map projections and geodetic coordinate systems gis. Objectives coordinate systems and map projections for gis. The process of projection involves distorition of area, distance, shape, and angles. Understanding map projections, datums, and coordinate systems.
Circumference of lines of latitude getting smaller, maps width staying constant. 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. Similar systems based on angles from baselines are often referred to as polar systems. Georeferencing, map projections, cartographic conceptsmap projectionscoordinate systems. A map projection is the systematic transformation of locations on the earth latitudelongitude to planar coordinates. Understanding projections and coordinate systems important knowledge to have, especially if you deal with many different sets of data that come from different sources. 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. Select a suitable map projection or coordinate system.
This article describes the theory behind datums, projections and coordinate systems, and highlights the importance of using the correct one for a given purpose. Sep 15, 2017 introduction to geographic information systems 25,349 views 30. Georeferencing, map projections, cartographic conceptsmap projectionscoordinate systemsdatum. What it wont do is the geographicdatum transformation part if. Articulate the leader in rapid elearning and communications. Introduction to coordinate systems and projections fondren. A projected or planimetric coordinate system that maps locations on the earths three. 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. Download coordinate systems and map projections book pdf free download link or read online here in pdf. Maling gis applications spring 2004 objectives malings assumption. Coordinate systems geographic coordinates latitude and longitude geocentric coordinates x, y, z mass centre of the earth cartesian coordinates datums horizontal and vertical references ellipsoid geoid mean sea level vertical elevation geoid undulation role of gravity map projections properties.
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. 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. The figures on this page are the intellectual property of peter h. The study of map projections is the characterization of these distortions. Coordinate systems are referenced to the physical earth surface through the use of datums. 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. Coordinate systems and map projections 2nd edition.
Given a cylindrical projection, the x scale must increase away from equator. Read online coordinate systems and map projections book pdf free download link book now. 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. Download as ppt, pdf, txt or read online from scribd. Due to the irregular shape of the earth, different map projections are used projections can be used with different datums projection is a. Coordinate systems and map projections, second edition. Application of remote sensing and geographical information system in civil engineering date. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. Georeferencing, map projections, cartographic concepts. Brown abstract the mapmisc package provides functions for visualising geospatial data, including fetching background map layers, producing colour scales and legends, and. Geodesy, map projections and coordinate systems synopsis.
A datum is simply a foundation and reference for spatial measurements. However, map projection refers specifically to a cartographic projection. Maps, coordinate reference systems and visualising. Understanding coordinate systems and map projections. Cilconical map plane is tangent along a line, most commonly a parallel of latitude which is then the maps standard parallel cone is cut along a meridian, and the meridian opposite the cut is the maps central meridian alternatively,y, y cone may intersect secant tog, globe. Units of measurement typically feet or meters for projected coordinate systems or decimal degrees for latitudelongitude.
Coordinate systems and map projections 2nd edition elsevier. Gis data differs from other data types, primarily because it contains geographic coordinates describing the location of the data on the earth. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. Purchase coordinate systems and map projections 2nd edition. Select a suitable map projection or coordinate system summary. 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.
Map projections can be generally classified according to what spatial attribute they preserve. All books are in clear copy here, and all files are secure so dont worry about it. There are several ways to refer to a coordinate system. 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. The signs of x,y coordinates in a projected coordinate system. Coordinate systems, map projections, and geographic datum. July 24th 30th, 2010 projections and coordinate systems page 2 projections, spheroids, datums and coordinate systems we are trying to represent a 3we are trying to represent a 3dimensional, roundish, lumpy earth on a flat map we cant do this unless we project this roundish object onto a flat surface a round planet on a flat map.
Geographic coordinates, latitude and longitude, are in fact not considered projected. Arcmap will reproject all layers that have coordinate systems that arent the same as the data frames. The appearance, classification and naming of map projections. Coordinate systems, projections, and transformations. Buy coordinate systems and map projections, second edition on free shipping on qualified orders. 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. With a smallscale map, your choice of map projection determines the overall appearance of the map. A gcs is often incorrectly called a datum, but a datum is only one part of a gcs.
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. Coordinate systems and map projections pdf book manual. Gis positional data are primarily printed maps which have been digitized. Download the list of supported geographic and vertical coordinate systems.
Dec 03, 2011 common map projections what are some common map projections and what agencies use them. Projections and coordinate systems apostol panayotov, phd february 2014. Map projections and coordinate systems gis courses. This means different y scales in different parts of the map what is the xscale factor. Understanding projections and coordinate systems important knowledge to have, especially if you deal with many different sets of. The shape of the earth and the geodetic datum concept are covered on pages 46.
The terms datum, projection and coordinate system are often misinterpreted and misunderstood. Understanding datums, coordinate systems and map projections. This is changing somewhat as more data are collected by gps. 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.
Page 79 discuss map scale and the basics of coordinate systems. 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. Earth, datum, projections, maps and coordinate systems 2 3. Map projection, coordinate system and datum youtube. It is perpendicular to the direction of gravity pull. Gis needs to be able to register data from different. Coordinate systems enable geographic datasets to use common locations for integration. Geodesy, map projections and coordinate systems synopsis of class 6, gis in water resources, fall 2011 the fundamentals of the material to be covered in this class are sufficiently extensive that this synopsis extends to three pages, rather than the two pages used. A working manual available online scanned file from the usgs of john p. A coordinate system, datum, and map projection are all components of the coordinate reference system for a spatial object. 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. 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. Copies of the standards for flood risk analysis and mapping. The earth exists in threedimensions but, other than globes, most representations of the earth are two dimensional.
Introduction to geographic information systems 25,349 views 30. Map projection, data frame and coordinates system geonet. The process of converting a threedimensional space to a twodimensional map is called projection. 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. Ellipsoidal coordinate systems reference a mathematically derived spheroidal or ellipsoidal volumetric surface. Georeferencing, map projections, cartographic concepts map. Maps, coordinate reference systems and visualising geographic data with mapmisc by patrick e. Pdf coordinate systems and map projections rcz uz on.
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