Horizontal (Datum/Control)
Refers to the network of known horizontal geographic positions used as references for mapping and spatial accuracy.
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What is Horizontal (Datum/Control)?
A reference framework known as "horizontal datum/control" is used to pinpoint exact positions on the surface of the Earth in terms of latitude and longitude (horizontal position). Control points are surveyed sites with precise, known coordinates that act as reference markers, whereas a horizontal datum is a mathematical representation of the Earth that serves as a foundation for measuring geographic coordinates.
Control points and horizontal datums work together to allow:
Reliable surveying and mapping
Regular alignment of spatial data
Combining several datasets from various sources
Typical examples are the NAD83 and WGS84 datums. In order to guarantee geographic correctness and consistency, horizontal control is crucial in geodesy, building, navigation, and GIS.
Related Keywords
In mapping and surveying, a horizontal datum is a reference system that specifies the exact location of points on the surface of the Earth. Based on a particular model of the Earth's form (ellipsoid) and position with respect to the planet's centre, it determines the origin, direction, and scale for latitude and longitude coordinates.
Typically expressed in terms of latitude and longitude (or x and y in a projected coordinate system), horizontal control point coordinates specify the exact geographic location of reference points on the surface of the Earth. These points provide spatial precision and consistency between measurements by acting as fixed references for engineering, mapping, and surveying operations.
Geographic coordinates are defined using horizontal datums, such as WGS84 (World Geodetic System 1984) and NAD83 (North American Datum 1983). While WGS84 is a global datum used for GPS and global mapping, NAD83 is mostly used in North America and is based on the approximate form of the Earth for the continent. Although the two datums are similar, they differ slightly in their geocentric origins and reference ellipsoids, which might cause shifts of a few meters when converting between them.
A reference framework for precisely measuring and charting locations on the Earth's surface is provided by a geodetic horizontal datum. It guarantees uniformity in location across maps, satellite data, and engineering projects, making it crucial for surveying, navigation, GIS, and remote sensing. Horizontal datums facilitate accurate geospatial analysis, infrastructure planning, and the smooth integration of spatial datasets by specifying latitude, longitude, and the shape of the Earth.