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Difference between WGS84 and NAD83
The World Geodetic System 1984 (WGS84) and the North American Datum 1983 (NAD83) are two geodetic coordinate reference systems used for position on the earth's surface.
It is important to use the correct reference frame for a given application, as using the wrong one can result in significant positioning errors. WGS84 is the reference frame used by GPS devices, whereas NAD83 is used by mapping and surveying applications in North America.
Read this article to find out more about WGS84 and NAD83 and how they are different from each other.
What is WGS84?
WGS 84 determines the Earth's orientation in space by describing its rotation and position relative to the celestial sphere with a set of parameters. The rotational velocity of the Earth, its orientation relative to a fixed reference frame, and the position of the Earth's centre of mass are among these factors.
WGS 84 contains a global network of ground control points that offer constant and accurate measurements of the earth's surface. These ground control points are used to precisely locate a GPS receiver and calculate the coordinates of features on the earth's surface.
WGS84 is the standard reference system for many mapping and navigation applications, such as aviation, maritime navigation, and surveying. GPS satellites use WGS-84 as the reference system for their orbital features and clock corrections, allowing GPS receivers to identify their position on the Earth's surface with pinpoint accuracy.
The WGS 84 ellipsoid is the mathematical model of the Earth's shape that is used as a reference surface for geographic coordinates. The semi-major axis and flattening of an ellipsoid are both measured in metres. The semi-major axis represents the ellipsoid's equatorial radius, whereas the flattening represents the difference between the polar and equatorial radii divided by the equatorial radius.
Overall, WGS-84 is important in enabling accurate and dependable navigation and mapping around the world. It is constantly maintained and updated to account for changes in the Earth's shape and mass distribution, ensuring that it remains a reliable reference system for many years to come.
What is NAD83?
NAD83 (North American Datum 1983) is a geodetic reference system used in North America for mapping and surveying. It is the primary reference system for all mapping and surveying activities in Canada, the United States, and Mexico and is based on a network of survey markers.
NAD83 is based on a survey marker network that was developed across North America between 1984 and 1991. These markers were used to create a geodetic reference frame that accounts for the flaws in the Earth's form caused by local variations in gravity and tectonic plate movement. As a result, NAD83 is more accurate in North America than the WGS84 system.
The NAD83 reference system is composed of several components −
The NAD83 ellipsoid − This is the mathematical model of the Earth's shape that is used as a reference surface for geographic coordinates. The NAD83 ellipsoid is similar to the WGS84 ellipsoid but has a slightly different shape that accounts for irregularities in the Earth's shape caused by local variations in gravity.
The NAD83 datum − This is a frame of reference used to connect the NAD83 coordinate system to the Earth's surface. The NAD83 datum is a collection of geodetic control points developed across North America using high-precision surveying techniques. The NAD83 coordinate system was adjusted using these control points to account for irregularities in the Earth's shape caused by local variations in gravity and other factors.
The NAD83 transformation parameters − These equations are used to convert coordinates between the NAD83 and WGS84 reference systems. The transformation parameters account for changes in orientation and position between the two reference systems and are used to ensure that coordinates in one system can be accurately transformed to coordinates in the other.
Difference between WGS84 and NAD83
The following table highlights the major differences between WGS84 and NAD83 −
Characteristics |
WGS84 |
NAD83 |
|---|---|---|
Definition |
WGS84 is a worldwide reference frame system. |
NAD83 (North American Datum 1983) is a geodetic reference system used in North America for mapping and surveying. |
Stands for |
World Geodetic System |
North American Datum |
Ellipsoid |
Oblate spheroid with a semi-major axis of 6,378,137m and flattening of 1/298.257223563 |
It is quite similar to WGS84 but slightly has different shapes that take into account local variations in gravity. |
Usage |
It is used by the United States Department of Defence. |
It is used in the U.S., Canada, Central America, and Mexico. |
Applications |
It is suitable for global navigation and mapping, including GPS, GLONASS, Galileo, and other global positioning systems. |
It is widely used in North America for navigation, mapping, surveying, and other geospatial applications that include land-use planning, environmental monitoring, and emergency response. |
Compatibility |
WGS-84 is compatible with many of the global positioning systems and mapping software. |
NAD83 is not compatible with WGS84 and may cause problems when integrating data from different sources or using different mapping software. |
Conclusion
In conclusion, WGS84 and NAD83 are two geodetic reference systems that are used for mapping and navigation. WGS 84 is a global reference system based on a mathematical model of the earth's shape, whereas NAD 83 is a North American geodetic reference system based on a network of survey markers.
The primary difference between the two reference systems is their origin and how they account for the curvature of the Earth, irregularities in its shape, and the movement of tectonic plates. These differences can have significant practical consequences for applications requiring great precision.
To ensure accurate and consistent results, it is important to use the suitable reference system for a given application. In addition, without sufficient conversion, any coordinates calculated in one system may not be directly comparable to coordinates in the other system. As a result, it is important to understand the differences between the two systems and the best conversion methods to use.
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