1.3 Principles of Cartography – It’s a ‘Square World’! Or is it?

Above shows the hierarchy of mapping.

The foundation is the datum. Geographic coordinates (latitude and longitude) describe points in the datum. These are then converted into Projection coordinates.

Without knowledge of the datum, projection coordinates are not unique and can easily be wrongly mapped.

Why is it necessary to project geographic coordinates? We do this for three primary reasons:

• Ease of communication
• Ease of computation
• Presentation and Planning