From a point of referring to the line from the north, according to a clockwise direction to the target level of the direction angle between the lines, called azimuth.
         Since each point has really north, magnetic north and vertical coordinates of the North three different means to the line of the north, therefore, from a point to a goal, have three different azimuth.
         (1) true azimuth. Point to a point in the direction of the Arctic line to the line called True North, and longitude, also called the true meridian. From a point of true north to the money, depending on the direction of a clockwise direction to the target angle sailor between money and told the true azimuth of the point. Often used in precision measurement.
         (2) The Earth is a big magnet, the location of the Earth's magnetic poles are constantly changing, a point to the direction of magnetic north is called magnetic north line to line, also called the magnetic meridian. Topographic map in the north and south magnetic map of the southern profile, magnetic north of a straight line between two points, the radial magnetic maps. From a point of magnetic north from the line, depending on the direction of a clockwise direction to the target level of inter-line angle, called the point of the magnetic azimuth.
         (3) azimuth coordinates. The coordinates of a point from the vertical line from the north, depending on the direction of a clockwise direction to the target level of inter-money angle, called the coordinates of the point azimuth.
Azimuth in the mapping, geological and geophysical exploration, aviation, navigation, and artillery fire when the troops marched, are widely used. Different azimuth can be converted into each other.