Graticule is the network of lines of latitude and longitude upon which a map is drawn.

Imaginary lines around Earth that form a grid.

A network of parallels and meridians on a map chart.

While sometimes described as a grid, a graticule is not necessarily a grid, and there are several different ways to describe coordinates within the graticule. A common example of a graticule is a grid of lines on a map which corresponds to longitude and latitude.


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Utm:The Universal Transverse Mercator coordinate system.

The UTM system divides the surface of Earth between 80°S and 84°N latitude into 60 zones, each 6° of longitude in width and centered over a meridian of longitude. Zone 1 is bounded by longitude 180° to 174° W and is centered on the 177th West meridian. Zone numbering increases in an easterly direction.

Geoid: Earth is not an perfect shape it is ellipsoidal. The ellisoidal earth is the geoid. The geoid surface is irregular, without landmasses.

The geoid

Ellipsoid: A three-dimensional mathematical model which approximates the shape of the geoid. Many different ellipsoids have been developed for continents or individual countries to minimize local deviations from the geoid. The standard global ellipsoid is the World Geodetic System of 1984 (WGS 84). …

{x^2 \over a^2}+{y^2 \over b^2}+{z^2 \over c^2}=1,