Coordinate Systems

• Geographic Coordinate System
  • Uses latitude and longitude and is expressed in decimal degrees
• Projected Coordinate System
  • Uses linear units
  • Projects the earth onto a flat surface

Datums

• A datum mathematically defines the shape and size of the earth and it’s orientation in space
• A transformation is a mathematical calculation used to convert coordinates referenced to one datum to coordinates referenced to another datum.

Projections

• A projection is the process by which we translate (or project) the spherical globe onto a flat surface.
• The object onto which maps are projected (i.e. cylinder, cone, or plane) affects the way the map appears.
• All map projections maintain certain properties while distorting others.

---