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The definition of NAVD 88 uses the Helmert orthometric height, which calculates the location of the geoid (which approximates MSL) from modeled local gravity. [citation needed] The NAVD 88 model is based on then-available measurements, and remains fixed despite later improved geoid models. [citation needed]
The new gravimetric geoid model is the product of the Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project. These new reference frames are intended to be easier to access and to maintain than NAD 83 and NAVD 88, which rely on physical survey marks that deteriorate over time. [2]
The system is based on the datums NAD 83 and NAVD 88. [3] In 2024 or 2025, [needs update] the NSRS will be modernized with a focus on Global Navigation Satellite Systems (GNSS) and geoid use. It will use the following four frames of reference, each representing a tectonic plate: [4] [5] North American Terrestrial Reference Frame of 2022 (NATRF2022)
The North American-Pacific Geopotential Datum of 2022 (NAPGD2022) will separately define the height system of the United States and its territories, replacing NAVD88. [3] It will use a geoid model accurate to 1 centimeter (0.4") to relate orthometric height to ellipsoidal height measured by GPS, eliminating the need for future leveling projects.
In North America elevations are given using either Sea Level Datum of 1929, also called the National Geodetic Vertical Datum of 1929 (NGVD 29) or the North American Vertical Datum of 1988 (NAVD 88). Confusion often occurs when a user sees an elevation value using the older datum. Some may assume the elevation is incorrect and in fact the reader ...
Satellite geodesy is geodesy by means of artificial satellites —the measurement of the form and dimensions of Earth, the location of objects on its surface and the figure of the Earth 's gravity field by means of artificial satellite techniques. It belongs to the broader field of space geodesy. Traditional astronomical geodesy is not commonly ...
Geodesy. EPSG Geodetic Parameter Dataset (also EPSG registry) is a public registry of geodetic datums, spatial reference systems, Earth ellipsoids, coordinate transformations and related units of measurement, originated by a member of the European Petroleum Survey Group (EPSG) in 1985. Each entity is assigned an EPSG code between 1024 and 32767 ...
v. t. e. A spatial reference system (SRS) or coordinate reference system (CRS) is a framework used to precisely measure locations on the surface of Earth as coordinates. It is thus the application of the abstract mathematics of coordinate systems and analytic geometry to geographic space. A particular SRS specification (for example, " Universal ...