Geodetic datum - Wikipedia
A geodetic reference datum is a known and constant surface which is used to describe the location of unknown points on Earth. Since reference datums can have different radii and different center points, a specific point on Earth can have substantially different coordinates depending on the datum used to make the measurement.
Geodetic Datums: NAD 27, NAD 83 and WGS84 - GIS Geography
Geodetic datums form the basis of coordinates of all horizontal positions on Earth. We reference all coordinates on Earth to a horizontal datum. The North American Datum of 1927 (NAD27) is one of the main three geodetic datums in North America.
Datums and Reference Frames | Datums | National Geodetic …
2023年12月7日 · A geodetic datum or reference frame is an abstract coordinate system with a reference surface (such as sea level) that serves to provide known locations to begin surveys and create maps.
What is a datum? | NGS Facts | NGS INFO - About Us | National Geodetic …
A geodetic datum is an abstract coordinate system with a reference surface (such as sea level) that serves to provide known locations to begin surveys and create maps. In this way, datums act similar to starting points when you give someone directions.
What are Geodetic Datums? | Video Library | NGS Training and …
2022年8月10日 · National Geodetic Survey educational video explaining the basic concepts behind geodetic datums, where they are used, and why it is important to know about and use the correct datums.
Lesson 5: Geodetic Datums - John A. Dutton e-Education Institute
Three distinct figures are involved in a geodetic datum for latitude, longitude, and height: the geoid, the reference ellipsoid, and the topographic surface. Due in large measure to the ascendancy of satellite geodesy, it has become highly desirable that they share a common center.
Understanding Geodetic Datums: Importance and Applications
2024年9月9日 · A geodetic datum is a fundamental reference framework used in mapping and surveying. It serves as a standard point or surface from which measurements are taken. Think of it as a base point that helps surveyors establish locations accurately on …
2.3: Datums, Coordinate Systems, and Map Projections
2023年5月21日 · A datum serves this purpose and specifies precisely the orientation and origins of the lines of latitude and longitude relative to the center of the earth or spheroid. Depending on the need, situation, and location, there are several datums to choose from.
World Geodetic System (WGS84) - GIS Geography
Horizontal datums precisely specify each location on Earth’s surface in latitude and longitude or other coordinate systems. For instance, NAD27, NAD83, and WGS84 are examples of geodetic datums. Using geographic coordinate systems, we can define positions on Earth.
World Geodetic System - Wikipedia
The World Geodetic System (WGS) is a standard used in cartography, geodesy, and satellite navigation including GPS. The current version, WGS 84, defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum, and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM).