Has a false origin located 500000 m west of the central. Make a note of the ellipsoid used and the projection parameters central meridian, reference latitude, standard parallel 1, standard parallel 2, false easting and false northing. False origin metres 200 000 w 250 000 s 600 000 w 750 000 s 500 000 w 0 s table 1. A false origin is established w and s of the zone coordinates are read to the e and n of the false origin 2,065,000 feet e. Page 79 discuss map scale and the basics of coordinate systems. This gives cartographers a map to work with always in meters. State plane coordinate system state cartographers office.
Map projection definition of map projection by the free. The utm coordinate system is a universally used plane coordinate system except for polar regions. The origin of the graticule 0,0 is defined by where the equator and prime meridian intersect. It is perpendicular to the direction of gravity pull. In regards to map projections, a false origin is an adjustment of that original origin at 0,0 to a different location either east or north of the zone from which measurements are being taken. Map projection earth surface in reality is a curved surface with no perfect geometrical shape. A false origin is used in order to make finding map coordinates easier on a map. Universal transverse mercator utm zones false northing, false easting. The location of the map projection origin on the surface, and.
It is used for road maps and weather maps azimuthal planar projection. How universal transverse mercator utm works gis geography. To ensure that the northing and easting coordinates on a map are not negative, map projections may set up a false origin, specified in terms of false northing and false easting values, that offset the true origin. A map projection is a systematic transformation of the latitudes and longitudes of positions on the surface of the earth to a. False northing gis definition,meaning online encyclopedia. This puts the origin for the southern hemisphere very near the south pole uses a transverse mercator projection centered on the zones central meridian exhibits minimal distortion farm service agency production emergencies and compliance division washington dc subject. The equal earth map projection is a new equalarea pseudocylindrical projection for world maps. The geoid is defined as the surface of the earths gravity field, which is approximately the same as mean sea level. Each map projection has a set of parameters that you must define. Map projections are introduced on pages 1012, and pages.
Measure northings in feet from origin measure eastings in feet from origin. The globe is then divided into four geographical quadrants that are based on compass bearings from the origin. The central meridian and latitude of origin were from the above table. Map projection parameters irish grid ig originated as a classically derived transverse mercator projection, the ig was defined to meet the above criteria. Map projection definition and meaning collins english. Mapping in a globe is an easy way to map the earth. North and south are above and below the equator, and west and. It is important to remember that the look of a projected graticule depends on several projection parameters, including latitude of projection origin, central meridian, standard lines, and others. This booklet provides a conceptual introduction to map projections and geographic reference systems. Geographic coordinate system gis wiki the gis encyclopedia. A map projection is the mathematical algorithm used for this transformation.
Arctoolbox permits the transformation of data from one map projection to another. At the conclusion of this session, you will be able to. Since the mass of the earth is not uniform at all points, and the direction of gravity changes, the. North and south are above and below the equator, and west and east are to the left and right of the prime meridian.
False northing northing at the projection natural origin. It became the standard map projection for nautical purposes because of its ability to represent lines of constant course, known as rhumb lines or loxodromes, as straight segments that conserve the angles with the meridians. Also, a coordinate reference system may use more than one map projection. Coordinate systems, projections, and transformations. Usually it is brought down to the lower left of the map so all of the x,y coordinates are positive. D h maling, coordinate systems and map projections. The mercator uses an upright cylinder for its map projection. Map projection coordinate systems wiley online library. The universal polar stereographic map is normally limited to 84 north in the north polar aspect and 80 south in the south polar aspect. The scale factor was computed as shown in the equation above. The false origin may be aligned to a known realworld coordinate or not, but for the purposes of data capture, bearings and distances may be measured using the local coordinate system rather than global coordinates. The definition of the map projection for projected coordinate systems. Map projection parameters map projection parameters include standard lines standard parallels and standard meridians, principal scale, scale factor, central lines, false easting, and false northing.
Measurement as well as sharing of data and details is always difficult if a map is represented on globe. Understand the difference between map projections and coordinate systems. False northinga linear value applied to the origin of the. The norwegian mapping authority has provided an alternative map projection more suitable for construction projects. Understanding map projections landing page for kartoweb. The parameters specify the origin and customize a projection for your area of interest. Most local surveyors are well served by using map projections such as the state plane. Origin longitude 70 10 00 w central meridian false northing 0. Introduction to maps,coordinate system and projection system. Choose the appropriate projection and datum for your map. False easting gis definition,meaning online encyclopedia.
Nj state plane coordinate systems one or more zones for each state. It generally does not maintain true directions, but angles and shapes are maintained at infinitesimal scale. In cartography, a map projection is a way to flatten a globes surface into a plane in order to make a map. A geographic coordinate system gcs includes information about the datum, spheroid, prime meridian, and angular unit of measure, usually in degrees. Final primary and contiguous county designations for crop year 2012 for all crop disaster losses keywords. Develop a rudimental knowledge of map projections and datums. Scroll down to view details of the projection parameters and associated ellipsoids. The mercator projection is a cylindrical map projection presented by the flemish geographer and cartographer gerardus mercator in 1569. This handbook is intended to be a coordinate reference systems user manual.
Angular parameters use the geographic coordinate system units, while linear parameters use the projected coordinate system units. The false easting is the xcoordinate value assigned relative to this origin. For the transverse mercator projection used in utm, the parameters associated are the latitude and longitude of the natural origin, the and false easting, and an overall scale factor. As its name implies, this map projection uses a cone as its developable surface. Then, using the map projection conversion from a commercial software package, a transverse mercator projection was defined. Map projections, map projections flashcards quizlet.
Like zones in the state plane coordinate system, this map projection shows a limited area of the united states. The origin of a grid is a fixed point from where measurements are taken, typically found at the x, y coordinates 0,0. Customized map projections may look entirely different from the archetypes described above figure 16. Map projection mathematical geometric method for projecting spherical. Map of earth showing lines of latitude horizontally and longitude vertically, robinson projection. A geodetic datum and any adjustments to that datum see pages 58 2. Hit projection, select projections of the united states, and among the choices offered, select the albers equalarea conic projection. The false easting and false northing the units reference ellipsoid 36 37. Similar to the utm, this projection has a false easting and a false northing. Projections are like political parties, they distort everything.
This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. 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. The 1975 mapping adjustment resulted in alteration of the scale factor on the central meridian to 1. The origin at the intersection of meridians is assigned a false easting and false northing of 2,000,000 meters. Mercator projection an overview sciencedirect topics.
The universal transverse mercator is horrible for smallscale lessdetailed maps like world atlases and perfect for mapping narrow regions. Distances are accurate along the central meridian if the scale factor is 1. The peal projection engine acronym list pe projection engine gcs, geogcs geographic coordinate system pcs, projcs projected coordinate system vcs, vertcs vertical coordinate system. Listed below are map projections relevant to new south wales. Utm zones are flattened using the transverse mercator projection, and a rectangular grid network of straight horizontal and vertical lines is superimposed on each zone. This map projection is practical for nautical applications due to its ability to represent lines of constant course, known as rhumb lines, as straight segments that conserve the angles with the meridians. Lecture 2 map projections and gis coordinate systems. Local coordinate systems are often used for largescale small area mapping. A map projection by itself isnt enough to define a projected coordinate system.
The first handbook provided background material on map projections and. A false easting and northing are used in the universal transverse mercator coordinate system to prevent the use of negative numbers. The northing false origin for vicgrid94 has been adopted as 2,500,000 metres south of the intersection of the parallel of latitude 37o s and the central meridian rather than the 4,500,000 specified for the original vicgrid. This booklet provides a conceptual introduction to.
Additional information is available in the gda2020 technical manual, on icsms australian. Choosing a map projection the choice of map projection is made to give the most accurate possible representation of the geographic information, given that some distortion is inevitable. Map projections distortions projection refers to the notion of shining light through the earth surface and projecting latitudes, longitudes and geographic features onto a developable surface. Exercise in map projections university of texas at austin. 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.
The utm projection flattens the sphere 60 times by shifting the cylinder central meridian 6 for each zone. Although meridians inside the zone and on zone boundaries converge towards. False northing is a linear value applied to the origin of the y coordinates. The projection is conformal, so angles are preserved but distances are distorted. Our gnss publications contain several publications related to datums, transformations and projections.
The 1975 mapping adjustment resulted in alteration of the scale. In the process of projection the earth is represented by a model an ellipsoid. The shape of the earth and the geodetic datum concept are covered on pages 46. Map projection formed by projecting points and lines from globe onto cone, it is accurate of small areas but has lots of distortion for large areas.
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