1. Coordinates

2. Space is important How can we represent this space numerically? 2D and 3D

3. 3D Coordinate System

4. Spherical Coordinates 3D only Does not ignore curvature of Earth Uses two angles of rotation (Lat/Lon) and radius to specify locations

5. Longitude aka Meridian Measures East-West Vary from +180° E to -180° W Meridians 0° -10° -20° -30° -40° -50° -60° -70° -80° -90° -100° -110° -120° -130° -140° -150°10° 20° West East

6. Latitude aka Parallels Measures North-South Vary from +90° N to -90° S North Pole 90° Parallels 80° N 70° 60° 50° 40° 30° 20° 10° 0° 10° 20° 30° S Equator

7. Spherical Coordinate Representation Both latitude and longitude are typically represented in two ways Degrees, Minutes, Seconds (DMS) -34°23’45.23”, +124°12’45.32” Decimal Degrees (DD) used by computers -34.395897, 124.212589

8. 2D Coordinate Systems

9. Define spatial location and extent Define spatial location and extent 2D (x,y) 3D (x,y,z) Cartesian Coordinates

10. GIS data typically uses Cartesian system Ignores curvature of Earth For small areas, usually acceptable

11. Cartesian Coordinate Representation Many possible representations Could even make your own Common Representations State Plane Coordinate System (SPCS) Universal Transverse Mercator Coordinate System (UTM)

12. State Plane Coordinate System Set of 126 geographic zones Designed for specific regions of USA Useful because… Simple calculations Accurate within zones Comes in NAD27 and NAD83 flavors Coordinates represented in Feet

13. State Plane Coordinate System Each state may have multiple State Plane zones Provides a common coordinate reference for horizontal coordinates over county areas while limiting error to specified maximums Based on two types of map projections Lambert conformal conic Transverse Mercator

15. Universal Transverse Mercator Coordinate System A set of 60 zones across the World Useful because… Simple calculations Accurate within zones Coordinates represented in Meters

16. Universal Transverse Mercator (UTM) Global coordinate system Divides Earth into zones that are 6° wide and extend from 80°S to 84°N Numbered from 1 to 60 heading East from 180°W Zones also split into North and South at Equator UTM is common for data and study areas that cover large regions Coordinates always positive and specified in Eastings (Y), and Northings (X)