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The World Geographic Reference System (GEOREF) is a geocode, a grid-based method of specifying locations on the surface of the Earth. GEOREF is essentially based on the geographic system of latitude and longitude , but using a simpler and more flexible notation .
Example: grid with coordinates (φ,λ,z) where z is the elevation. A standard Geoid surface. The z coordinate is zero for all grid, thus can be omitted, (φ,λ). Ancient standards, before 1687 (the Newton's Principia publication), used a "reference sphere"; in nowadays the Geoid is mathematically abstracted as reference ellipsoid.
Geodetic latitude and geocentric latitude have different definitions. Geodetic latitude is defined as the angle between the equatorial plane and the surface normal at a point on the ellipsoid, whereas geocentric latitude is defined as the angle between the equatorial plane and a radial line connecting the centre of the ellipsoid to a point on the surface (see figure).
The United States National Grid (USNG) is a multi-purpose location system of grid references used in the United States. It provides a nationally consistent "language of location", optimized for local applications, in a compact, user friendly format. It is similar in design to the national grid reference systems used in other countries.
If the reference direction is north (either true north, magnetic north, or grid north), the bearing is termed an absolute bearing. In a contemporary land navigation context, true, magnetic, and grid bearings are always measured in this way, with true north, magnetic north, or grid north being 0° in a 360-degree system. [5]
For example, a truncated grid reference may be used where the general location is already known to participants and may be assumed. [10] Because the (leading) most significant digits specify the part of the world and the (trailing) least significant digits provide a precision that is not needed in most circumstances, they may be unnecessary for ...
A spatial reference system (SRS) or coordinate reference system (CRS) is a framework used to precisely measure locations on the surface of Earth as coordinates.It is thus the application of the abstract mathematics of coordinate systems and analytic geometry to geographic space.
The Earth-centered, Earth-fixed coordinate system (acronym ECEF), also known as the geocentric coordinate system, is a cartesian spatial reference system that represents locations in the vicinity of the Earth (including its surface, interior, atmosphere, and surrounding outer space) as X, Y, and Z measurements from its center of mass.