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Cylindrical equal-area projection with standard parallel at the equator and an aspect ratio of π (3.14). 1910 Behrmann: Cylindrical Equal-area Walter Behrmann: Cylindrical equal-area projection with standard parallels at 30°N/S and an aspect ratio of (3/4)π ≈ 2.356. 2002 Hobo–Dyer: Cylindrical Equal-area Mick Dyer
The scale of a map is the ratio of a distance on the map to the corresponding distance on the ground. This simple concept is complicated by the curvature of the Earth's surface, which forces scale to vary across a map. Because of this variation, the concept of scale becomes meaningful in two distinct ways.
However, if the map is marked with an accurate and finely spaced latitude scale from which the latitude may be read directly—as is the case for the Mercator 1569 world map (sheets 3, 9, 15) and all subsequent nautical charts—the meridian distance between two latitudes φ 1 and φ 2 is simply
Scale at an angular distance of 5° (in longitude) away from the central meridian is less than 0.4% greater than scale at the central meridian, and is about 1.54% at an angular distance of 10°. In the secant version the scale is reduced on the equator and it is true on two lines parallel to the projected equator (and corresponding to two ...
The X column is the ratio of the length of the parallel to the length of the equator; the Y column can be multiplied by 0.2536 [11] to obtain the ratio of the distance of that parallel from the equator to the length of the equator. [7] [9] Coordinates of points on a map are computed as follows: [7] [9]
Many large-scale maps use conformal projections because figures in large-scale maps can be regarded as small enough. The figures on the maps are nearly similar to their physical counterparts. A non-conformal projection can be used in a limited domain such that the projection is locally conformal. Glueing many maps together restores roundness.
In each zone the scale factor of the central meridian reduces the diameter of the transverse cylinder to produce a secant projection with two standard lines, or lines of true scale, about 180 km on each side of, and about parallel to, the central meridian (Arc cos 0.9996 = 1.62° at the Equator). The scale is less than 1 inside the standard ...
The scale of a map projection must be interpreted as a nominal scale. (The usage large and small in relation to map scales relates to their expressions as fractions. The fraction 1/10,000 used for a local map is much larger than the 1/100,000,000 used for a global map.