Scale and True Scale?

Abstract

According to Snyder (1987), no map projection shows scale correctly throughout the map, but there are usually one or more lines on the map along which the scale remains true. By choosing the locations of these lines properly, the distortions elsewhere may be minimized, although some distortions may still be large, depending on the size of the area being mapped and the projection. Some projections show true scale between one or two points and every other point on the map, or along every meridian. These are called equidistant projections.