- Purpose and function. The National Geodetic Survey is an office of NOAA's National Ocean Service. Its core function is to maintain the National Spatial Reference System (NSRS), "a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States".
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Aug 21, 2020 · NOAA’s National Geodetic Survey (NGS) provides the framework for all positioning activities in the Nation. The foundational elements of latitude, longitude, elevation, and shoreline information impact a wide range of important activities.
The National Geodetic Survey ( NGS ), formerly the United States Survey of the Coast (1807–1836), United States Coast Survey (1836–1878), and United States Coast and Geodetic Survey ( USC&GS) (1878–1970), is a United States federal agency that defines and manages a national coordinate system, providing the foundation for transportation and communication; mapping and charting; and a large number of applications of science and engineering.
The mission of the National Geodetic Survey (NGS) is to define, maintain and provide access to the National Spatial Reference System (NSRS) (PDF, 123 KB). The NSRS provides a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States and its territories.
- Role of NGS
- History of NHMP
- Science of Height Modernization
- Applications and Benefits of Height Modernization
- Additional Information
The NGS mission is to define, maintain, and provide access to the National Spatial Reference System(NSRS) to meet our nation’s economic, social, and environmental needs. The vertical component of the NSRS is the vertical datum, which is a collection of specific points on the Earth with known heights or elevations above or below a reference surface approximating mean sea level. Round brass disks (bench marks) set in concrete or bedrock or stainless steel rods driven to refusal are most often used to mark positions in the vertical datum. The traditional method for determining the elevation of these vertical bench marks is differential leveling, but the advanced technology of Global Navigation Satellite System(GNSS) has begun to replace this classical technique of vertical measurement in many situations. The goals of the National Height Modernization Program(NHMP) are to provide access to accurate, reliable heights nationally; to develop standards that are consistent across the nation;...
Since the first general adjustment of the geodetic leveling network was completed in 1900, NGS has been responsible for defining the official, legal vertical reference frame in the United States. In 1929, NGS compiled all of the existing vertical bench marks and created the National Geodetic Vertical Datum of 1929 (NGVD 29). Since then, movements of the Earth’s crust have changed the elevations of many bench marks, and other bench marks have been disturbed or destroyed as communities expand or roadways widen. In 1988, the vertical control network, including several thousand kilometers of new leveling, was again mathematicallyadjusted to remove inaccuracies and to correct distortions. The new datum, called the North American Vertical Datum of 1988 (NAVD 88), was defined through the leveling network and is the official vertical datumfor civilian surveying and mapping activities in the United States performed or financed by the Federal Government. During the 1980’s and 1990’s, there we...
The current Height Modernization program uses orthometric heights from traditional leveling and ellipsoid heights from GNSS to create a geoid height model referenced to the NAVD 88. Conventional geodetic leveling is precise but labor intensive, so it is not feasible or practical to level across the country today as has been done in the past; additionally, leveling yields cross-country error build-up. It is possible to obtain accurate heights through GNSS, and NGS has published guidelines that define equipment requirements, field procedures and data collection parameters, basic control requirements, and processing and analysis procedures. Accuracy of GPS-derived orthometric heights depends on both the accuracy of the geoid modeland the accuracy of the NAVD 88 control. NGS makes a gravitational geoid model based on gravity data collected from a variety of sources and a “Hybrid” model that builds on the gravitational model using GNSS on bench marks to enable a fit to NAVD 88. The early...
Accurate, reliable, and up-to-date heights are essential for a wide range of activities. Traditional users include surveyors and engineers who manage construction and infrastructure projects such as bridges, dams, and levees. Emergency managers need accurate heights to plan and monitor evacuation routes, and there are a multitude of applications for accurate heights in flood or inundation mapping and modeling. Scientistsneed accurate heights to monitor and model changes in heights when studying crustal motion, subsidence, isostatic readjustment and seasonal changes like frost heave. Agriculture is a relatively new user community, but it uses accurate heights to more efficiently control equipment and apply fertilizer. Natural resource managers can use heights to manage restoration projects, complete natural resource inventories, or monitor erosion and/or sea level change. Finally, the increased use of Geographic Information Systems(GIS) has resulted in greater demand for both elevati...
To learn more about projects that have already been completed, check out our regional and state partnersweb pages and resources. To learn more about the science of geodesy, check out the NGS website and the NOS Education site.
Between 1987 and 1997, the National Geodetic Survey, in cooperation with other Federal, State and local surveying agencies conducted a resurvey of the United States using Global Positioning System (GPS) observations often referred to as the High Accuracy Reference Networks (HARNs).
A set of accurately measured points is the basis for the National Spatial Reference System (NSRS), which allows differents kinds of maps to be consistent with one another. Many organizations use geodesy to map: the U.S. shoreline, determine land boundaries and improve transporation and navigation safety.
Active Geodetic Control (CORS) Adjust Leveling (LOCUS) Survey Mark Datasheets; Process GPS Data (OPUS) Calibration Base Lines (CBLs) User-submitted Survey Projects (Bluebooking) GRAV-D; Geoid Slope Validation Survey (GSVS) Height Modernization; Leveling; Mark Recovery; NAD 83(2011) epoch 2010.00 coordinates on passive control; Publication Library
Jul 01, 2020 · The National Geodetic Survey (NGS), an office of NOAA's National Ocean Service, manages a network of Continuously Operating Reference Stations (CORS) that provide Global Navigation Satellite System (GNSS) data consisting of carrier phase and code range measurements in support of three dimensional positioning, meteorology, space weather, and geophysical applications throughout the United States, its territories, and a few foreign countries.
The purpose of the Geodetic Survey section is to establish precisely located monuments on the North Carolina Grid System and Bench Marks referenced to a vertical datum (NGVD 1929 and NAVD 1988).
Process your GNSS data in the National Spatial Reference System. ... Survey Planning and Data ... National Geodetic Survey / Last modified by NGS.OPUS V 2.6 May ...