Map Projections Basic Principles 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. This type of figure is termed an oblate ellipsoid or spheroid, and is the three-dimensional shape obtained by rotating an ellipse about its shorter axis.
The NOAA website states the system to have been developed by the United States Army Corps of Engineersstarting in the early s,  and published material[ specify ] that does state an origin apparently based on that account.
From onward the US Army employed a very similar system, but with the now-standard 0. For the remaining areas of Earth, including Hawaiithe International Ellipsoid  was used.
For different geographic regions, other datum systems e.
ED50, NAD83 can be used. Prior to the development of the Universal Transverse Mercator coordinate system, several European nations demonstrated the utility of grid-based conformal maps by mapping their territory during the interwar period.
Calculating the distance between two points on these maps could be performed more easily in the field using the Pythagorean theorem than was possible using the trigonometric formulas required under the graticule-based system of latitude and longitude. The transverse Mercator projection is a variant of the Mercator projectionwhich was originally developed by the Flemish geographer and cartographer Gerardus Mercatorin This projection is conformalwhich means it preserves angles and therefore shapes across small regions.
However, it distorts distance and area. Each of the 60 zones uses a transverse Mercator projection that can map a region of large north-south extent with low distortion. Distortion of scale increases to 1.
The scale is less than 1 inside the standard lines and greater than 1 outside them, but the overall distortion is minimized. For more on its history, see Clifford J. However, it is often convenient or necessary to measure a series of locations on a single grid when some are located in two adjacent zones.
Around the boundaries of large scale maps 1: Ideally, the coordinates of each position should be measured on the grid for the zone in which they are located, but because the scale factor is still relatively small near zone boundaries, it is possible to overlap measurements into an adjoining zone for some distance when necessary.
Latitude bands[ edit ] Each zone is segmented into 20 latitude bands. Latitude bands "A" and "B" do exist, as do bands "Y" and "Z". They cover the western and eastern sides of the Antarctic and Arctic regions respectively.
A convenient mnemonic to remember is that the letter "N" is the first letter in "northern hemisphere", so any letter coming before "N" in the alphabet is in the southern hemisphere, and any letter "N" or after is in the northern hemisphere.
Notation[ edit ] The combination of a zone and a latitude band defines a grid zone. The zone is always written first, followed by the latitude band. For example, see image, top righta position in Toronto, OntarioCanadawould find itself in zone 17 and latitude band "T", thus the full grid zone reference is "17T".
The grid zones serve to delineate irregular UTM zone boundaries. They also are an integral part of the military grid reference system. A note of caution: A method also is used that simply adds N or S following the zone number to indicate North or South hemisphere the easting and northing coordinates along with the zone number supplying everything necessary to geolocate a position except which hemisphere.
However, this method has caused some confusion since, for instance, "50S" can mean southern hemisphere but also grid zone "50S" in the northern hemisphere. Exceptions[ edit ] These grid zones are uniform over the globe, except in two areas. The three grid zones 32X, 34X and 36X are not used.The Universal Transverse Mercator (UTM) system is a specialized application of the transverse Mercator projection.
The globe is divided into 60 north and south zones, each spanning 6° of longitude. Each zone has its own central meridian. The Transverse Mercator projection illustrated above (Figure ) minimizes distortion within UTM zone Fifty-nine variations on this projection are used to minimize distortion in the other 59 UTM zones.
In every case, distortion is no greater than 1 part in 1, The Universal Transverse Mercator (UTM) projection is a specialized application of the transverse Mercator projection.
The globe is divided into 60 north and south zones, each spanning 6° of longitude. The syntax is rutadeltambor.com_latlon(EASTING, NORTHING, ZONE NUMBER, ZONE LETTER). The return has the form (LATITUDE, LONGITUDE).
Since the zone letter is not strictly needed for the conversion you may also the northern parameter instead, which is a named .
UTM - Universal Transverse Mercator UTM Projection. As the name suggests, the Universal Transverse Mercator projection is based on the cylindrical Transverse Mercator projection. The cylinder in the Transverse Mercator projection is tangent along a meridian (line of longitude) or it is secant, in which case it cuts through the earth at two standard meridians.
OVERVIEWUTM coordinates are based on a family of Transverse Mercator map projections (two for each UTM zone, with one for each N/S hemisphere).
The earth is divided into 60 zones, each 6° wide in longitude (with the exception of a few non-standard-width zones for Svalbard and southwest of .