Coordinate Systems Georeferencing System: o Once we agree on the size and shape of the Earth, we can develop measurement systems. The two important measurement systems are: Geographic Coordinate Systems: Latitude/Longitude angular measurements for an ellipsoidal earth Cartesian Coordinate System: X, Y (easting, northing) distance measurement systems for a flat earth Earth Coordinate Geometry o The locations of any objects can be precisely determined with coordinate systems developed based on earth and plane coordinate geometry o Earth coordinate system: Longitude latitude (in decimal degrees) Degrees, minutes, seconds o Determining locations on the earth is based on sexagesimal (1 o =60’ , 1’=60”) scale. That is, a circle is 360 degrees, each degree into 60 minutes, and each minute into 60 seconds Earth Coordinate Geometry: o Lines that measure position north/south are called parallels: Parallels: Are of differing length – shorter away from the equator Are parallel to one another Are nearly equally spaced Range from 0 0 – 90 0 (N: + , S: -) o Lines that measure position east/west are called meridians: Meridians: Are equal in length Are spaced widest at the equator with convergence to the points of the poles Range from 0 0 – 180 0 (E: + , W: -) Latitude : is the location on the earth’s surface between the equator and either the North or the South pole The angle for a point is equal to the angle between the equator and the radius from the earth center to the point on the surface An imaginary plane is passed through a point and parallel to the equatorial plane, this will intersect the Earth surface and form a parallel of latitude Latitude is represented with degree, minute, and seconds, labeled with a capital N or S, that is, the positional north or south of the equator o For example: 45 0 30’30”
Longitude : using the same sexagesimal system as latitude, measures location east (+) or west (-) of the prime meridian that has 0 degree of longitude. The maximum of longitude is 180 degrees W or E.
- Fall '18
- Geodesy, Geographic coordinate system, Earth Coordinate Geometry