Creating a map involves fitting the round, three-dimensional world onto a flat, two-dimensional surface. Using mathematics, mapmakers have created a variety of less-than-perfect solutions to this problem.

These solutions, known as map projections, can produce different maps depicting a particular place with very different appearances. On a flat map, conceptions of size, shape and distance are compromised in the projection process. All flat maps contain some type of distortion, but a conscientious cartographer chooses a projection that best correlates with their purpose for the map. When a cartographer chooses to draw a map on a small scale (that is, showing a greater amount of space in less detail), the map becomes more distorted since the difficulty of factoring in the curve of the earth becomes greater. On the other hand, a larger-scale map (which focuses on a smaller amount of space) offers fewer projection problems because there is less curvature to take into account.


Roll over the links below to compare the Cassini and Central Projections.

Mercator Projecton

Central Projection

Cassini Projection Oregon Public Broadcasting, CASSINI PROJECTION WORLD MAP (2006) Courtesy of Southern Oregon ESD and the U.S. Department of Education, copyright 2007.

This projection accurately represents continent shapes along the central meridian, making it appropriate for topographic mapping along this latitude. However, shapes become distorted toward the top and bottom of the map.

Central Projection Oregon Public Broadcasting, CENTRAL PROJECTION WORLD MAP (2006) Courtesy of Southern Oregon ESD and the U.S. Department of Education, copyright 2007.

This projection is highly distorted in many respects. However, any straight line drawn on this map will always be the shortest route between two points.