The mercator projection

As in all cylindrical projectionsparallels and meridians are straight and perpendicular to each other.

The mercator projection

As in all cylindrical projectionsparallels and meridians are straight and perpendicular to each other. In accomplishing this, the unavoidable east-west stretching of the map, which increases as distance away from the equator increases, is accompanied in the Mercator projection by a corresponding north-south stretching, so that at every point location the east-west scale is the same as the north-south scale, making it a conformal map projection.

Conformal projections preserve angles around all locations. Because the linear scale of a Mercator map increases with latitude, it distorts the size of geographical objects far from the equator and conveys a distorted perception of the overall geometry of the planet.

A Mercator map can therefore never fully show the polar areas as long as the projection is based on a cylinder centered on the Earth's rotation axis; see the transverse Mercator projection for another application.

All lines of constant bearing rhumbs or loxodromes—those making constant angles with the meridians are represented by straight segments on a Mercator map. The two properties, conformality and straight rhumb lines, make this projection uniquely suited to marine navigation: Although the method of construction is not explained by the author, Mercator probably used a graphical method, transferring some rhumb lines previously plotted on a globe to a square graticule grid formed by lines of latitude and longitudeand then adjusting the spacing between parallels so that those lines became straight, making the same angle with the meridians as in the globe.

The development of the Mercator projection represented a major breakthrough in the nautical cartography of the 16th century. However, it was much ahead of its time, since the old navigational and surveying techniques were not compatible with its use in navigation.

Two main problems prevented its immediate application: Only in the middle of the 18th century, after the marine chronometer was invented and the spatial distribution of magnetic declination was known, could the Mercator projection be fully adopted by navigators.

Several authors are associated with the development of Mercator projection: German Erhard Etzlaub c. Portuguese mathematician and cosmographer Pedro Nunes —who first described the loxodrome and its use in marine navigation, and suggested the construction of a nautical atlas composed of several large-scale sheets in the cylindrical equidistant projection as a way to minimize distortion of directions.

If these sheets were brought to the same scale and assembled an approximation of the Mercator projection would be obtained English mathematician Edward Wright c. English mathematicians Thomas Harriot — and Henry Bond c.

Uses[ edit ] The Mercator projection portrays Greenland as larger than Australia; in actuality, Australia is more than three and a half times as large as Greenland. As on all map projectionsshapes or sizes are distortions of the true layout of the Earth's surface.

The Mercator projection exaggerates areas far from the equator. Greenland appears larger than Africawhen in reality Africa's area is 14 times greater and Greenland's is comparable to Algeria 's alone.

Africa also appears to be roughly the same size as Europewhen in reality Africa is nearly 3 times larger. Alaska takes as much area on the map as Brazilwhen Brazil's area is nearly five times that of Alaska.

Finland appears with a greater north-south extent than Indiaalthough India's is greater. Antarctica appears as the biggest continent and would be infinitely large on a complete mapalthough it is actually the fifth in area. A relation between the Mercator projection and the true size of each country.

The Mercator projection is still used commonly for navigation. On the other hand, because of great land area distortions, it is not well suited for general world maps. Therefore, Mercator himself used the equal-area sinusoidal projection to show relative areas.

However, despite such distortions, Mercator projection was, especially in the late 19th and early 20th centuries, perhaps the most common projection used in world maps, despite being much criticized for this use.

The Mercator projection is still commonly used for areas near the equator, however, where distortion is minimal. Arno Peters stirred controversy when he proposed what is now usually called the Gall—Peters projection as the alternative to the Mercator.

The projection he promoted is a specific parameterization of the cylindrical equal-area projection. In response, a resolution by seven North American geographical groups deprecated the use of cylindrical projections for general purpose world maps, which would include both the Mercator and the Gall—Peters.

Mapsand others use a variant of the Mercator projection for their map images [8] called Web Mercator or Google Web Mercator. Despite its obvious scale variation at small scales, the projection is well-suited as an interactive world map that can be zoomed seamlessly to large-scale local maps, where there is relatively little distortion due to the variant projection's near- conformality.

Many different methods exist for calculating a. The simplest include a the equatorial radius of the ellipsoid, b the arithmetic or geometric mean of the semi-axes of the ellipsoid, c the radius of the sphere having the same volume as the ellipsoid.

These are the values used for numerical examples in later sections. Only high-accuracy cartography on large scale maps requires an ellipsoidal model.A cylindrical map projection in which the meridians and parallels appear as lines crossing at right angles and in which areas appear greater farther from the equator.

Straight line segments represent true bearings, thus making this projection useful for navigation.

Mercator projection | Definition, Uses, & Limitations |

[After Gerhardus Mercator.] a. Mercator Projection. The Mercator projection is a map projection that was widely used for navigation since loxodromes are straight lines (although great circles are curved).

The following equations place the x-axis of the projection on the equator and the y-axis at . Mercator’s map was so useful to sailors that its popularity eventually caught on with landlubbers.

Today, it’s still the most often used map projection in the world. The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in It became the standard map projection for nautical navigation because of its ability to represent lines of constant course.

It turns out Monday was Steve Waterman's birthday. His site has posters of his map, plus maybe the world's only Winkel Tripel-critiquing poetry.

Gerardus Mercator: Gerardus Mercator, Flemish cartographer whose most important innovation was a map, embodying what was later known as the Mercator projection, on which parallels and meridians are rendered as straight lines spaced so as to produce at any point an .

The mercator projection
Mercator projection - Wikipedia