1. Different Map Projections There’s more than one way to skin a sphere.

2. Map-Making You can’t take a sphere and roll it out and make it into a two-dimensional map without some distortion. Distortion means something is not quite accurate. When a map is created, one of the following (at least) is going to be distorted: – Area/Size, Shape, Direction, or Distance

3. Basic Projections Types of projections include conic, cylindrical, planar, and oval, as the following examples show.

5. Mercator – The Mercator projection has straight meridians and parallels that intersect at right angles. Scale is true at the equator or at two standard parallels equidistant from the equator. There is extreme area distortion in the higher latitudes. The projection is often used for marine navigation because all straight lines on the map are lines of constant azimuth.

7. Peters – Peters: The Peters projection is a cylindrical equal- area projection that de-emphasizes area exaggerations in high latitudes by shifting the standard parallels to 45 or 47 degrees.

9. Robinson Robinson: The Robinson projection is based on tables of coordinates, not mathematical formulas. The projection distorts shape, area, scale, and distance in an attempt to balance the errors of projection properties.

11. Goode’s Homolosine Equal-Area Projection: It is an example of an oval projection and shows area accurately, but it gives the impression that the earth has been torn, peeled, and flattened like an orange. There are interruptions in the oceans. It distorts proximity, distance, direction, and shape in some areas.

13. Lambert Azimuthal Equal Area: The Lambert azimuthal equal-area projection is sometimes used to map large ocean areas. The central meridian is a straight line, others are curved. A straight line drawn through the center point is on a great circle.

15. Lambert Conformal Conic: Area, and shape are distorted away from standard parallels. Directions are true in limited areas. Used for maps of North America.

17. What are the pros and cons of each? -Mercator? -Robinson? -Peters? -Miller? -Lambert?

18. “Life By the Numbers: Shape of the World” Video -This video from Safari Montage describes some of the uses and projections of maps

19. Choice of Maps National Geographic has wrestled for decades with the choice of a projection for reference maps of the world. In 1922 the Society adopted the Van der Grinten projection, which encloses the world in a circle. Our cartographers switched in 1988 to the Robinson projection, on which the high latitudes are less distorted in size (but more so in shape). A decade later, the Society began using the Winkel Tripel projection, which provides a better balance between size and shape.

20. Van der Grinten map http://en.wikipedia.org/wiki/Van_der_Grinten_projection http://www.nationalgeographic.com/features/2000/projections/ax/content_frame.html

21. Robinson Projection http://www.nationalgeographic.com/features/ 2000/projections/ax/content_frame.html

22. Winkel Tripel Projection Map http://en.wikipedia.org/wiki/Winkel_tripel_projection

23. Winkel Tripel Projection Neither equal-area or conformal Distorted in all four areas some Less than Robinson’s “Pleasant” and “right” treatment and presentation of the earth Used by National Geographic today From around 1921