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Ellipsoidal height is the vertical distance between a point on the Earth's surface and the reference ellipsoid, which is a mathematically defined surface approximating the shape of the Earth. It is crucial in geodesy and GPS applications, where precise positioning is required, but it does not account for local variations in the Earth's gravity field, unlike orthometric height which relates to sea level.
Concept
Geodesy is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space. It plays a crucial role in navigation, mapping, and understanding Earth's physical properties and changes over time.
A reference ellipsoid is a mathematically defined surface that approximates the shape of the Earth, used as a model for geodetic calculations and mapping. It simplifies the complex shape of the Earth into an ellipsoidal form, which accounts for the equatorial bulge due to rotation, providing a standardized frame of reference for geographic and geodetic data.
The Global Positioning System (GPS) is a satellite-based navigation system that provides geolocation and time information to a GPS receiver anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. Originally developed for military use, GPS has become an essential tool for various civilian applications, including navigation, mapping, and timing services.
Orthometric height is the height of a point above the geoid, which is considered the true physical surface of the Earth. It is crucial in geodesy and surveying as it provides a more accurate representation of elevation compared to ellipsoidal height, which measures from a mathematical model of the Earth's surface.
Concept
The geoid is a model of Earth's shape that represents the mean sea level across the globe, accounting for gravitational variations. It serves as a reference surface from which to measure elevations and is crucial for accurate geodetic and oceanographic applications.
A vertical datum is a reference surface used to measure elevations and depths, serving as a baseline for geospatial data. It is crucial for ensuring consistency in elevation data across different geographic locations and applications, such as mapping, construction, and navigation.
Earth's gravity field is the force that attracts objects towards the center of the Earth, influencing everything from the motion of satellites to ocean tides. It varies slightly across the planet due to factors like Earth's rotation, the distribution of mass in its interior, and topographical features like mountains and valleys.
The Geodetic Coordinate System is a method used to precisely pinpoint locations on the Earth's surface by utilizing a spherical or ellipsoidal model of the Earth. It uses latitude, longitude, and sometimes height above a reference ellipsoid to define positions in a three-dimensional space, essential for navigation, mapping, and geospatial analysis.
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