Читать книгу Geography For Dummies - Jerry T. Mitchell - Страница 85

Generally speaking, map projections belong to one of three families: azimuthal, cylindrical, and conic (see Figure 4-4).

 Azimuthal (or planar): A flat piece of paper (or plane, hence planar) is placed against the globe. The globe is then projected onto the flat paper, rendering a flat map.

 Cylindrical: A paper cylinder is placed over a globe. The globe is projected onto the paper. The cylinder is then cut vertically and unwrapped from the globe, yielding a flat map of the world.

 Conical: A conical paper hat is placed on the globe. The portion of the globe under the hat is projected onto the paper. The paper is cut in a straight line from its edge to the tip of the cone. The cone is then opened up and put down flat.

(© John Wiley & Sons Inc.)

FIGURE 4-4: Families of map projections.

This reminds me to remind you that the process of projection does not literally involve projecting a globe onto a flat surface. Instead, mathematical formulas are used to plot the locations of lines (latitude, longitude, continental boundaries, and so on) on maps. Thanks to satellite imagery, you can now check the accuracy of your work in a way that was never possible before.