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A waypoint is a reference point in physical space used for purposes of navigation, otherwise known as a landmark. ==Concept== Waypoints are sets of coordinates that identify a point in physical space. Coordinates used can vary depending on the application. For terrestrial navigation these coordinates can include longitude and latitude. Air navigation also includes altitude. Waypoints have only become widespread for navigational use by the layman since the development of advanced navigational systems, such as the Global Positioning System (GPS) and certain other types of radio navigation. Waypoints located on the surface of the Earth are usually defined in two dimensions (''e.g.,'' longitude and latitude); those used in the Earth's atmosphere or in outer space are defined in at least three dimensions (four if time is one of the coordinates, as it might be for some waypoints outside the Earth). Although the term ''waypoint'' has only entered common use in recent years, the equivalent of a waypoint in all but name has existed for as long as human beings have navigated. Waypoints have traditionally been associated with distinctive features of the real world, such as rock formations, springs, oases, mountains, buildings, roadways, waterways, railways, and so on. Today, these associations persist, but waypoints are more often associated with physical artifacts created specifically for navigation, such as radio beacons, buoys, satellites, control points, etc. In the modern world, waypoints are increasingly abstract, often having no obvious relationship to any distinctive features of the real world. These waypoints are used to help define invisible routing paths for navigation. For example, artificial airways—“highways in the sky” created specifically for purposes of air navigation—often have no clear connection to features of the real world, and consist only of a series of abstract waypoints in the sky through which pilots navigate; these airways are designed to facilitate air traffic control and routing of traffic between heavily traveled locations, and do not reference natural terrain features. Abstract waypoints of this kind have been made practical by modern navigation technologies, such as land-based radio beacons and the satellite-based GPS. Abstract waypoints typically have only specified longitude and latitude or UTM coordinates plus the reference datum, and often a name if they are marked on charts, and are located using a radio navigation system such as a VOR or GPS receiver. A waypoint can be a destination, a fix along a planned course used to make a journey, or simply a point of reference useful for navigation. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「waypoint」の詳細全文を読む スポンサード リンク
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