Chapter 4: Grid Coordinate systems
We call a planerectangular coordinate system based upon and mathematically placed on a map projection a grid
If you superimpose a square grid on the map, with divisions on a horizontal xaxis and a vertical yaxis
where the axes cross at the system’s origin, you’ve established the familiar Cartesian coordinate system.
Grid coordinate systems based on the Cartesian coordinate system are especially handy for map
analysis procedures as finding the distance or direction between locations or determining the area of a
mapped feature like a lake.
Universal Transverse Mercator system (UTM)
The best known grid coordinate system of international scope is UTM system. The UTM grid
extends around the world from 84˚N to 80˚S. Sixty northsouth zones are used, each six degrees
Each zone is individually numbered from west to east, starting with Zone 1 from 180˚W to
An easting is simply the eastwest xcoordinate in a grid coordinate system—that is, it is the
distance east from the origin. In both the northern and southern hemispheres, an easting value of
500,000 meters is assigned to the central meridian of each UTM zone. This value called the false
easting, is added to al