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Learn about the current and historical vertical datums for the United States and its territories. A vertical datum is a surface of zero elevation to which heights are referenced.
- National Geodetic Survey
Geodetic Tool Kit; Geodetic Software; Web Services; Vertical...
- Datum Tutorial
Geodetic Datums. Referenced Ellipsoid. GEOID. Horizontal...
- Datums
National Geodetic Survey Datums, Frames and Projections...
- National Geodetic Survey
Originally known as Sea Level Datum of 1929, NGVD 29 was determined and published by the United States Coast and Geodetic Survey and used to measure the elevation of a point above and depression below mean sea level (MSL).
- Background
- Recommended Datums
- Datum Documentation
- Placement of Documentation
- Additional Information
- Frequently Asked Questions About Datums
- GeneratedCaptionsTabForHeroSec
Scientists frequently use geospatial data obtained from multiple sources, and datums commonly must be standardized before datasets that are referenced to different or unknown datums can be used. The North American Datum of 1927 (NAD 27) and the National Geodetic Vertical Datum of 1929 (NGVD 29) are considered superseded as the national standards. T...
The NAD 83 and the NAVD 88 are the recommended datums to use in USGS publication series information products. The use of these datums establishes a common reference for all horizontal and vertical data in the NSRS for the conterminous United States and Alaska. The NAD 83 and the NAVD 88 datums also provide the necessary linkages for Global Position...
Include datum documentation in a USGS publication series information product according to the following criteria. 1. The product refers to an altitude or an elevation (orthometric height). 1.1. State the vertical datum name and year in that document. 1.2. Example: "Vertical coordinate information is referenced to the North American Vertical Datum o...
Place the documentation in a USGS publication series information product according to the following criteria. 1. The product has a traditional book-report layout with front matter. 1.1. State the datum information (as described in "Datum Documentation" above) immediately following the conversion factors. If a vertical datum reference is needed with...
If the datum used for existing data is not apparent: 1. Refer to the required metadata that accompanies the dataset. 2. Query the dataset by using your geospatial software package. 3. Refer to the header file for the dataset. 4. Visually compare the dataset in question to a dataset of known datum. 5. Inspect information on the map or illustration s...
Refer to the following frequently asked questions (FAQs) about using and documenting horizontal and vertical datums in USGS publication series information products. Additional FAQs about datums are available at NOAA National Adjustment of 2011 (NA2011) Project Frequently Asked Questions (FAQs)web page. 1. Is the use of NAD 83 and NAVD 88 required?N...
Learn how to use and document the North American Vertical Datum of 1988 (NAVD 88) and other vertical datums in USGS publication series information products. Find links to NGS and NOAA resources for more information about datums and geoid models.
Nov 4, 2020 · Learn how the NAVD 88, the standard for accurate measurement of elevation across large distances in the U.S., was created and will be replaced by a new system. The article traces the evolution of geodetic surveying and leveling from 19th century to present.
The vertical datum is similarly "realized" through a collection of specific points on the Earth with known heights either above or below a nationally defined reference surface (e.g., mean sea level). Geodetic vertical datums are generally used to express land elevations.
