Mapmaking - The Science of Navigation - page 114

FIGURE 4.12. A Dymaxion-type map, resulting from projection onto a dodecahedron.
Which way is up? Thanks to Carlos Furuti ( www.progonos.com/furuti/MapProj/Normal/
ProjPoly/projPoly3.html) for kindly creating this image.
For example, there is only one type of conic projection that is equal-area,
and only one that is conformal. Other projections produce good properties
locally, or along a chosen meridian, or around the equator. Many projec-
tions are chosen as a compromise: they are distortion-free nowhere but
su√er from low distortion over a wide area. A popular example today is the
Winkel Tripel projection, which dates back to 1921 (fig. 4.13). It is currently
the preferred choice for the National Geographic Society world maps.
One example of a projection developed for a very specific purpose is the
space oblique Mercator projection, developed by the U.S. Geological Survey.
This projection produces no distortion along the ground track beneath an
orbiting satellite and only small distortion in a limited swath of the earth's
surface close to the ground track. Therefore, a remote-sensing satellite can
image the earth beneath it, and the data can be turned into a low-distortion
map by using this new type of projection.
The Miller projection is a version of the Mercator that is slightly modi-