Page 63 - 4670

severally defined by the various nations and organizations that adopt
them.
Coordinates can be plane or curvilinear, two-dimensional or
three-dimensional, or even one-dimensional. Many basic coordinate

systems are used to represent points in two-dimensional or three-
dimensional space.
Two-dimensional coordinate systems include:

- Cartesian coordinate system;
- Polar coordinate system;
- Parabolic coordinate system;
- Bipolar coordinates;

- Elliptic coordinates.
Three-dimensional systems include:
- Bipolar cylindrical coordinates;

- Cylindrical coordinate system;
- Spherical coordinate system;
- Parabolic cylindrical coordinates;

- Oblate spheroidal coordinates;
- Ellipsoidal coordinates and others.
These three-dimensional and two-dimensional systems used in

analytical geometry are often referred to as Rectangular and Plane
Cartesian systems respectively. René Descartes introduced the system
of coordinates based on orthogonal axes.
The simplest datum is an Earth Centered, Earth Fixed cartesian

datum (ECEF), whose origin is the center of mass of the Earth. Main
units are meters. It is characterized by the three right-handed
orthogonal axis X, Y, Z.

– The Z axis coicincides with the Earth’s rotation axis.
– The (X,Y) plane coincides with the equatorial plane.
– The (X,Z) plane contains the Earth’s rotation axis and the prime
meridian.

The Prime Meridian is the origin for longitudes.
The Equator is the origin for latitudes.
Geodetic latitude - angle from the equatorial plane to the vertical

direction of a line normal to the reference ellipsoid.
Geodetic longitude - angle between a reference plane and a plane
passing through the point, both planes being perpendicular to the

equatorial plane.

63