Common Coordinate Systems

Common Coordinate Systems

The following coordinate systems that are mostly used now a days

Latitude-longitude

Latitude-Longitude is not a two-dimensional coordinate system but is commonly referred to as one. Lines of latitude run eastwest parallel to the equator. Longitude lines run north-south and converge at the poles. Therefore, the length of one degree of longitude varies depending upon the latitude at which it is measured. For example, one degree of longitude at the equator is 111 kilometers in length, but the length of one degree of longitude converges to zero at the poles. Latitude-longitude is measured in degrees, minutes, and seconds, and because degrees aren’t associated with a standard length, they can’t be used as an accurate measure of distance or area. A common coordinate in latitude-longitude for South Carolina is 82.2 degrees west latitude and 34.2 degrees north longitude. In this example, the minutes and seconds are shown as decimals of one degree (i.e., decimal degrees). A great deal of commercially available data is packaged in latitude-longitude because it is by definition, not projected That way, the user can project it to whatever projection they are working in.

Universal Transverse Mercator (UTM)

Although UTM is technically a projection and NOT a coordinate system, it is commonly referred to as a coordinate system. This is because UTM is a set of zones with altered offsets and is based on the Transverse Mercator projection. It is used on the United States Geologic Survey (USGS)
Topographic maps. UTM Units must be in feet or meters, but is most often in meters.
Most of the data available from the College of Liberal Arts GIS data server is available in UTM, zone 17 with map units being in meters.

State Plane Coordinate System

Another common coordinate system is the state plane coordinate system. It divides all fifty states into zones. Each state is represented by anywhere from 1 to 10 zones. The shape of the zone(s) that cover the state determine which projection to use. Two projections are used most often:
lambert conic conformal for states with an east-west orientation like Tennessee, and Transverse Mercator for states with a north-south orientation like California. State Plane units must be in feet or meters but are most often in feet. South Carolina is mapped into one zone and is projected using the Lambert Conic Conformal projection. A common coordinate for SC data in the State Plane Coordinate System in feet is (1,600,000, 400,000).