GIS’s Roots in Cartography
The Shape of the Earth, Datums, Map Projections, and Coordinate Systems

History: What is the Shape of the World?

Eratosthenes (276 - 196 BC)

Eratosthenes’ Planar Map of the World

Ptolemy (2nd century, BC)

Rebirth of Geographic Thought

Twentieth Century Additions

The Earth’s Shape

Commonly Used Datums

Datum Shifts

The Map Projection Process

Types of Map Projections

Projection Distortion (1)

You Can’t Have It All!

Compromise Projections

Projections that Preserve Area

Projections that Preserve Shape
 (“Conformal Projections”)

Projections that Preserve Neither!
(Compromise Projections)

Which Projection Should We Use?

Projection Distortion (2)

More Information on Map Projections

Coordinate Systems (1)

Coordinate Systems (2)

Coordinate Systems for the Earth

Geographic Coordinates

Duncan Hall, in decimal degrees

UTM Coordinates

Duncan Hall, in UTM

Nifty DD        UTM Converters

Military Grid

State Plane Coordinate System

How Many Different Ways Can You Say “Here!”?

Map Scales (1)

Map Scales (2)

Vertical Exaggeration