{"id":6292,"date":"2024-06-05T00:45:33","date_gmt":"2024-06-05T07:45:33","guid":{"rendered":"https:\/\/pointonenav.com\/?p=6292"},"modified":"2024-06-19T18:18:35","modified_gmt":"2024-06-19T18:18:35","slug":"world-geodetic-system","status":"publish","type":"post","link":"https:\/\/pointonenav.com\/news\/world-geodetic-system\/","title":{"rendered":"WGS84: What is the World Geodetic System 1984"},"content":{"rendered":"
The World Geodetic System (WGS) is a standard that defines Earth-centered, Earth-fixed (ECEF) models, Earth gravitational, and <\/span>World Magnetic models.<\/span><\/a> In 1983, a new realization of WGS\u2014WGS84\u2014was developed from modifications of the Navy Navigation Satellite System (NNSS). Today, that realization is used worldwide for global positioning and navigation in automotive and mobile devices.<\/span><\/p>\n This article will provide a detailed exploration of World Geodetic Systems (WGS) and explain their importance in specific fields such as <\/span>construction surveying and mapping<\/span><\/a>. It will also clarify some technical WGS terms and demonstrate how WGS determines location.\u00a0<\/span><\/p>\n Finally, we\u2019ll explore other related geographic coordinate systems and address frequently asked questions about WGS84 and other World Geodetic Systems.<\/span><\/p>\n <\/p>\n WGS84 is a three-dimensional coordinate reference frame and the current world geodetic system standard used in navigation, mapping, drones, self-driving cars, robotics, satellite communications, and geospatial analysis. It comprises an ellipsoid, a horizontal datum, a vertical datum, and a coordinate system that accurately determines geographical locations.<\/span><\/p>\n For example, geodesists use WGS84 to define the coordinates of various locations on the Earth's surface so that they can say that a particular state or country is located at specific latitude and longitude coordinates.\u00a0<\/span><\/p>\n Before becoming the accurate and reliable standard today, WGS 84 has undergone several <\/span>updates<\/span><\/a>. The first is WGS84 (G730), followed by WGS84(G873), then WGS84(1150), and the current WGS84(G1674), with each version becoming more accurate.\u00a0<\/span><\/p>\n The WGS84 standard is the same one used with GPS devices, but people often confuse the WGS84 coordinate system with GPS, since GPS\/GNSS can be used with any datum.<\/span><\/p>\n GPS\/GNSS can be used with any datum as they are fundamentally designed to be datum-agnostic. But how do the coordinates provided by global positioning systems differ from those of the world geodetic system?\u00a0<\/span><\/p>\n Simply put, GPS coordinates can be converted to match different datums depending on the app's requirements or geographical area, but WGS84 remains consistent and is universally applied in GPS technologies. Also, while GPS typically provides raw satellite data that may initially reference a slightly different version of the WGS84 or other datums, WGS84 provides the standardized datum framework that aligns these coordinates globally.\u00a0<\/span><\/p>\n For survey and geodetic tasks requiring high precision, like <\/span>RTK surveying<\/span><\/a>, a consistent, standardized coordinate reference system (CRS) such as WGS84 is absolutely necessary. Why? It supports <\/span>absolute and relative navigation<\/span><\/a> by providing a common reference framework for accurate positioning and data comparison across different geographic locations. This means construction surveyors and geospatial analysts can access precise measurements quickly. WGS84 is also used in other fields, such as robotics and self-driving cars.<\/span><\/p>\n <\/p>\n Coordinate reference systems use coordinates to define how two-dimensional projected maps relate to true locations on the Earth. For instance, CRS uses ellipsoids and geoids to model the Earth's size and shape so users can achieve precise navigation.\u00a0<\/span><\/p>\n But do coordinate reference systems need standardization? Can you use any coordinate reference system on your GPS device? Let\u2019s explain.\u00a0<\/span><\/p>\n Ellipsoids provide a mathematical representation of the Earth\u2019s shape, while geoids show the Earth\u2019s mean sea level (elevation information), which is used for measuring precise surface elevations.\u00a0<\/span><\/p>\n Various coordinate reference frames and systems use ellipsoids to establish a base model of the Earth against which positional measurements are taken. These reference frames include WGS84, <\/span>NAD83<\/span><\/a>, ETRS89, GRS80, and many others. Each of these coordinate reference frames mentioned has its ellipsoid, with the world geodetic system of 1984 ellipsoid being the most popular one used as a reference surface for GPS coordinates.\u00a0<\/span><\/p>\n On the other hand, geoids adjust the height calculations provided by ellipsoids to account for local variations in the Earth's gravity, which impacts sea levels and, thus, the actual height of locations. Together, ellipsoids and geoids create a detailed, accurate mapping and geographic data analysis system.<\/span><\/p>\n Geoids are also important in land surveying, topographic mapping, <\/span>agricultural farm mapping<\/span><\/a>, and navigation as they convert ellipsoidal heights to orthometric heights, which engineers, architects, and construction workers can use.<\/span><\/p>\n A horizontal datum is a reference system that provides the longitude and latitude coordinates that determine exact locations on the Earth's surface. These datums measure movement in the earth's crusts, which can be further used to predict geological events and assess risk areas for engineering projects.\u00a0<\/span><\/p>\n CRS uses horizontal datums to reference geodetic measurements to rectangular coordinates. This means converting complex spherical measurements into simpler, planar grids, and it is necessary for accurately mapping and modeling the Earth for various applications such as navigation and environmental management.<\/span><\/p>\n While horizontal datums deal with latitude and longitudes, vertical datums reveal elevation and depth data. Instead of measuring movements in the earth\u2019s crust, these datums provide a reference point for height measurements necessary for constructing accurate topographical maps and models.\u00a0<\/span><\/p>\n CRS uses vertical datums to accurately measure heights below or above a surface, which is usually the sea level, and ensure consistent and reliable elevation readings across different geographic regions and over time.<\/span><\/p>\n Units in geodesy and coordinate reference systems are basically degrees, and these are how the data obtained from geographic measurements such as GPS readings are presented. Here\u2019s an example: if a GPS device measures the longitude of a particular location, it might display that longitude as 34.0522 degrees West.<\/span><\/p>\n <\/p>\n Here\u2019s how GPS devices and mapping applications use WGS84 to determine geographic locations using an ellipsoid model, a horizontal, and a vertical datum.<\/span><\/p>\n GPS and mapping applications use the WGS84 Unified Ellipsoid Model as a reference surface to arrive at the correct coordinates for a particular location. How? GPS devices usually have receivers that detect signals from multiple satellites orbiting the Earth, including the Global Positioning System (GPS) from the United States, GLONASS from Russia, Galileo from the European Union, and BeiDou from China.\u00a0<\/span><\/p>\n The signals from these major constellations interact with the ellipsoid model to compute accurate locations. GPS devices can translate satellite signals into precise ground coordinates by knowing the device\u2019s position in reference to the WGS84 ellipsoid. GPS devices can also use <\/span>RTK corrections<\/span><\/a> to derive an even more accurate result up to 1 cm accuracy.<\/span><\/p>\n While the ellipsoid model is a reference surface and the basis for many geodetic datums, the horizontal datum establishes the measurement framework for precisely calculating longitude and latitude. With this, GPS devices can accurately determine precise geographic positions.<\/span><\/p>\n The horizontal datum measures latitude and longitude, so if you want to assess elevation accurately, you\u2019ll need a vertical datum. Vertical datums measure heights above or below a reference surface. However, most GPS devices have built-in support for horizontal and vertical data, so you won\u2019t need to configure these settings manually.<\/span><\/p>\n <\/p>\n WGS84 is the most widely used geographic coordinate system, but there are also GRS 80, WGS72, NAD83, EPSG:3857, and EPSG:4326.<\/span><\/p>\n WGS72 is the World Geodetic System of 1972, created by the U.S. Department of Defense. While it is no longer in use, it is one of the earlier versions of WGS before WGS84. It was a military standard datum used to produce three-second digital elevation models, which are now used to enhance historical data comparison and analysis.<\/span><\/p>\n The Geodetic Reference System 1980 is the IAG's chosen standard for geodesy, earth science, and <\/span>inertial navigation applications<\/span><\/a>. It is the standard reference ellipsoid for the earth\u2019s size and shape adopted by the International Union of Geodesy and Geophysics in 1979.\u00a0<\/span><\/p>\nWhat is WGS84?<\/span><\/h2>\n
WGS84 vs GPS\u00a0<\/span><\/h3>\n
What are coordinate reference systems? How do they work?\u00a0<\/span><\/h2>\n
Ellipsoid or Geoid\u00a0<\/span><\/h3>\n
Horizontal Datum\u00a0<\/span><\/h3>\n
Vertical Datum\u00a0\u00a0<\/span><\/h3>\n
Units<\/span><\/h3>\n
How WGS84 Determines Location\u00a0<\/span><\/h2>\n
WGS84 Unified Ellipsoid Model<\/span><\/h3>\n
WGS84 Horizontal Datum\u00a0<\/span><\/h3>\n
WGS84 Vertical Datum\u00a0\u00a0<\/span><\/h3>\n
Related Geographic Coordinate Systems\u00a0<\/span><\/h2>\n
WGS72<\/span><\/h3>\n
GRS80<\/span><\/h3>\n