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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.
The angular velocity of the Earth is defined to be ω = 72.921 15 × 10 −6 rad/s. [ 11 ] This leads to several computed parameters such as the polar semi-minor axis b which equals a × (1 − f ) = 6 356 752 .3142 m , and the first eccentricity squared, e 2 = 6.694 379 990 14 × 10 −3 .
Vincenty's formulae are two related iterative methods used in geodesy to calculate the distance between two points on the surface of a spheroid, developed by Thaddeus Vincenty (1975a). They are based on the assumption that the figure of the Earth is an oblate spheroid, and hence are more accurate than methods that assume a spherical Earth, such ...
Going the "long way round" on a great circle between two points on a sphere is a geodesic but not the shortest path between the points. The map t → t 2 {\displaystyle t\to t^{2}} from the unit interval on the real number line to itself gives the shortest path between 0 and 1, but is not a geodesic because the velocity of the corresponding ...
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude. [1] It is the simplest, oldest and most widely used type of the various spatial reference systems that are in use, and forms the basis for most others.
A tunnel between points on Earth is defined by a Cartesian line through three-dimensional space between the points of interest. The tunnel distance D t = 2 R sin D 2 R {\displaystyle D_{\textrm {t}}=2R\sin {\frac {D}{2R}}} is the great-circle chord length and may be calculated as follows for the corresponding unit sphere:
A map from this sphere to a unit sphere of dimension n − 1 can be constructed by dividing each vector on this sphere by its length to form a unit length vector, which is a point on the unit sphere S n−1. This defines a continuous map from S to S n−1. The index of the vector field at the point is the degree of this map. It can be shown ...
The Universal Transverse Mercator (UTM) is a map projection system for assigning coordinates to locations on the surface of the Earth. Like the traditional method of latitude and longitude, it is a horizontal position representation, which means it ignores altitude and treats the earth surface as a perfect ellipsoid. However, it differs from ...