A horizontal geodetic datum based on an ellipsoid that has its origin at the earth's center of mass. Examples are the World Geodetic System of 1984, the North American Datum of 1983, and the Geodetic Datum of Australia of 1994.

When you need to accurately enter latitude and longitude coordinates in a GIS, the first step is to give it a datum. A geodetic datum uniquely defines all locations on Earth with coordinates. “Where would you be on Earth without having a reference to it?”

However, as the sophistication of satellite geodesy increased, the need for a truly global, geocentric datum became obvious. The horizontal and vertical information were no longer separate. Since satellites orbit around the center of mass of the earth, a position derived from space-based geodesy can be visualized as a vector originating from ...

The Modern Geocentric Datum. 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.

An earth-centered, or geocentric, datum uses the earth's center of mass as the origin. The most recently developed and widely used datum is WGS 1984. It serves as the framework for locational measurement worldwide.

A local datum aligns its ellipsoid to closely fit the earth's surface in a particular area. A point on the surface of the ellipsoid is matched to a particular position on the surface of the earth (the origin point of the datum).

2025年2月1日 · Yes, the North American Datum of 1983 (NAD83) is indeed geocentric. This means that it is based on a reference ellipsoid that has its origin at the center of the Earth’s mass. This is a fundamental characteristic that distinguishes it from older datums like NAD27.

The first official geodetic datum in the United States was the New England Datum, adopted in 1879. It was based on surveys in the eastern and northeastern states and referenced to the Clarke 1866 Ellipsoid.

On the right, the reference ellipsoid more closely fits the geoid overall. This is a geocentric datum, which is ideal for global mapping projects. The reference ellipsoid on the right is also centered at the center of Earth’s mass, which is important for GPS positioning.

Horizontal Datum = 1) shape and size of reference ellipsoid AND 2) location of ellipsoid center relative to center of mass of earth (geocenter).