Editing Projected coordinate system (section)

==History==
[[File:Spanggur Lake basin (US AMS, 1954).jpg|thumb|upright=1.1|1954 AMS map of a portion of the disputed [[Aksai Chin]] region, showing the  [[Military Grid Reference System|MGRS]] grid in blue.]]
The [[map projection]] and the [[geographic coordinate system]] (GCS, latitude and longitude) date to the [[Hellenistic period]], proliferating during the [[Enlightenment Era]] of the 18th century. However, their use as the basis for specifying precise locations, rather than latitude and longitude, is a 20th century innovation.

Among the earliest was the [[State Plane Coordinate System]] (SPCS), which was developed in the United States during the 1930s for surveying and engineering, because calculations such as distance are much simpler in a [[Cartesian coordinate system]] than the three-dimensional trigonometry of GCS. In the [[United Kingdom]], the first version of the [[Ordnance Survey National Grid|British National Grid]] was released in 1938, based on earlier experiments during [[World War I]] by the [[British Army|Army]] and the [[Ordnance Survey]].<ref name="russell">{{cite web |last1=Russell |first1=Don |title=Understanding Maps: The British National Grid |url=https://www.uncharted101.com/understanding-maps-the-british-national-grid/ |website=Uncharted 101 |access-date=21 December 2021}}</ref>

During [[World War II]], modern warfare practices required soldiers to quickly and accurately measure and report their location, leading to the printing of grids on maps by the U.S. [[Army Map Service]] (AMS) and other combatants.<ref name="raisz1948">{{cite book |last1=Raisz |first1=Erwin |title=General Cartography |date=1948 |publisher=McGraw-Hill |pages=225–229}}</ref> Initially, each [[theater of war]] was mapped in a custom projection with its own grid and coding system, but this resulted in confusion. This led to the development of the [[Universal Transverse Mercator coordinate system]], possibly adopted from a system originally developed by the German [[Wehrmacht]].<ref name="buchroithner">{{cite journal |last1=Buchroithner |first1=Manfred |last2=Pfahlbusch |first2=René |title=Geodetic grids in authoritative maps – new findings about the origin of the UTM Grid |journal=Cartography and Geographic Information Science |date=2017 |volume=44 |issue=3 |pages=186–200 |doi=10.1080/15230406.2015.1128851|s2cid=131732222 }}</ref> To facilitate unambiguous reporting, the alphanumeric [[Military Grid Reference System]] (MGRS) was then created as an encoding scheme for UTM coordinates to make them easier to communicate.<ref name="raisz1948"/>

After the War, UTM gradually gained users, especially in the scientific community. Because UTM zones do not align with political boundaries, several countries followed the United Kingdom in creating their own national or regional grid systems based on custom projections. The use and invention of such systems especially proliferated during the 1980s with the emergence of [[geographic information systems]]. GIS requires locations to be specified as precise coordinates and performs numerous calculations on them, making Cartesian geometry preferable to spherical trigonometry when computing power was at a premium. In recent years, the rise of global GIS datasets and [[satellite navigation]], along with an abundance of processing speed in personal computers, have led to a resurgence in the use of GCS. That said, projected coordinate systems are still very common in the GIS data stored in the [[spatial data infrastructure]]s (SDI) of local areas, such as cities, counties, states and provinces, and small countries.