Geodetic surveying is a specific type of surveying that takes the curvature of the Earth into account. These surveys cover large areas of land and provide high levels of accuracy.
Providing that a survey area covers up to 100 square miles, plane surveying is a useful survey technique. Plane surveys ignore any curvature of the Earth's surface. Lines between two points are straight lines and all angles are plane angles. Plane surveys are economical and are suitable for most major construction projects, like highways, bridges and factories. However, for plane surveys to be accurate, control points must exist between those straight lines. This is where geodetic surveying is useful.
Geodetic surveys cover much larger land areas and take the curvature of the Earth's surface into account. All lines in geodetic surveys are arcs and angles are spherical angles. These measurements are useful for making corrections for curvature on maps and plans. Geodetic surveys also provide the series of control points across the Earth's surface that make accurate plane surveys possible.
In the United States, the National Oceanic and Atmospheric Administration - NOAA - operates the National Geodetic Survey. This effort provides the backbone of all positioning projects in the nation. The National Geodetic Survey also maintains and provides access to the National Spacial Reference System, a consistent and definitive coordinate system with information on data such as latitude, longitude, gravity and shorelines.