Universal Transverse Mercator
Universal Transverse Mercator (UTM) system is a specialized application of the Transverse Mercator projection. The globe is divided into 60 north and south zones, each spanning 6° of longitude. Each zone has its own central meridian. Zones 1N and 1S start at -180° W. The limits of each zone are 84° N and 80° S, with the division between north and south zones occurring at the equator. The polar regions use the Universal Polar Stereographic coordinate system.
The origin for each zone is its central meridian and the equator. To eliminate negative coordinates, the coordinate system alters the coordinate values at the origin. The value given to the central meridian is the false easting, and the value assigned to the equator is the false northing. A false easting of 500,000 meters is applied. A north zone has a false northing of zero, while a south zone has a false northing of 10,000,000 meters.
Cylindrical projection. See the Transverse Mercator projection for the methodology.
Lines of contact
Two lines parallel to and approximately 180 km to each side of the central meridian of the UTM zone.
The central meridian and the equator.
Conformal. Accurate representation of small shapes. Minimal distortion of larger shapes within the zone.
Minimal distortion within each UTM zone.
Local angles are true.
Scale is constant along the central meridian but at a scale factor of 0.9996 to reduce lateral distortion within each zone. With this scale factor, lines lying 180 km east and west of and parallel to the central meridian have a scale factor of one.
Designed for a scale error not exceeding 0.1 percent within each zone. Error and distortion increase for regions that span more than one UTM zone. UTM is not designed for areas that span more than a few zones.
Data on a spheroid or an ellipsoid cannot be projected beyond 90° from the central meridian. In fact, the extent on a spheroid or ellipsoid should be limited to 12–15° on both sides of the central meridian. Beyond that range, data projected to the Transverse Mercator projection may not project back to the same position. Data on a sphere does not have these limitations.
A new implementation called Transverse_Mercator_complex has been added to the Projection Engine. It accurately projects to and from Transverse Mercator up to 80° from the central meridian. Because of the more complex mathematics involved, performance is affected.
Uses and applications
Used for United States topographic quadrangles, 1:100,000 scale.
Many countries use local UTM zones based on the official geographic coordinate systems in use.
Large-scale topographic mapping of the former Soviet Union.
Use the ZONE subcommand. If ZONE is not specified, the parameters are:
If the zone is not specified and the latitude is negative, a false northing of 10,000,000 meters is used.