Rectangular polyconic projection

Last updated
Rectangular polyconic projection of the world, with correct scale along the equator. Rectangular polyconic projection SW.jpg
Rectangular polyconic projection of the world, with correct scale along the equator.

The rectangular polyconic projection is a map projection was first mentioned in 1853 by the United States Coast Survey, where it was developed and used for portions of the U.S. exceeding about one square degree. It belongs to the polyconic projection class, which consists of map projections whose parallels are non-concentric circular arcs except for the equator, which is straight. Sometimes the rectangular polyconic is called the War Office projection due to its use by the British War Office for topographic maps. [1] It is not used much these days, with practically all military grid systems having moved onto conformal projection systems, typically modeled on the transverse Mercator projection.

Contents

Description

The rectangular polyconic has one specifiable latitude (along with the latitude of opposite sign) along which scale is correct. The scale is also true on the central meridian of the projection. Meridians are spaced such that they meet the parallels at right angles in equatorial aspect; this trait accounts for the name rectangular.

The projection is defined by: [2] :225:110

where:

To avoid division by zero, the formulas above are extended so that if φ = 0 then x = 2A and y = φ0. If φ1= 0 then A = 1/2(λ  λ0).

See also

Related Research Articles

<span class="mw-page-title-main">Mercator projection</span> Cylindrical conformal map projection

The Mercator projection is a conformal cylindrical map projection presented by Flemish geographer and cartographer Gerardus Mercator in 1569. It became the standard map projection for navigation due to its ability to represent north as 'up' and south as 'down' everywhere while preserving local directions and shapes. However, as a result, the Mercator projection inflates the size of objects the further they are from the equator. In a Mercator projection, landmasses such as Greenland and Antarctica appear far larger than they actually are relative to landmasses near the equator. Despite these drawbacks, the Mercator projection is well-suited to marine navigation and internet web maps and continues to be widely used today.

<span class="mw-page-title-main">Rhumb line</span> Arc crossing all meridians of longitude at the same angle

In navigation, a rhumb line, rhumb, or loxodrome is an arc crossing all meridians of longitude at the same angle, that is, a path with constant bearing as measured relative to true north.

<span class="mw-page-title-main">Transverse Mercator projection</span> Adaptation of the standard Mercator projection

The transverse Mercator map projection is an adaptation of the standard Mercator projection. The transverse version is widely used in national and international mapping systems around the world, including the Universal Transverse Mercator. When paired with a suitable geodetic datum, the transverse Mercator delivers high accuracy in zones less than a few degrees in east-west extent.

<span class="mw-page-title-main">Orthographic map projection</span> Azimuthal perspective map projection

Orthographic projection in cartography has been used since antiquity. Like the stereographic projection and gnomonic projection, orthographic projection is a perspective projection in which the sphere is projected onto a tangent plane or secant plane. The point of perspective for the orthographic projection is at infinite distance. It depicts a hemisphere of the globe as it appears from outer space, where the horizon is a great circle. The shapes and areas are distorted, particularly near the edges.

<span class="mw-page-title-main">Craig retroazimuthal projection</span> Retroazimuthal compromise map projection

The Craig retroazimuthal map projection was created by James Ireland Craig in 1909. It is a modified cylindrical projection. As a retroazimuthal projection, it preserves directions from everywhere to one location of interest that is configured during construction of the projection. The projection is sometimes known as the Mecca projection because Craig, who had worked in Egypt as a cartographer, created it to help Muslims find their qibla. In such maps, Mecca is the configurable location of interest.

<span class="mw-page-title-main">Mollweide projection</span> Pseudocylindrical equal-area map projection

The Mollweide projection is an equal-area, pseudocylindrical map projection generally used for maps of the world or celestial sphere. It is also known as the Babinet projection, homalographic projection, homolographic projection, and elliptical projection. The projection trades accuracy of angle and shape for accuracy of proportions in area, and as such is used where that property is needed, such as maps depicting global distributions.

<span class="mw-page-title-main">Azimuthal equidistant projection</span> Azimuthal equidistant map projection

The azimuthal equidistant projection is an azimuthal map projection. It has the useful properties that all points on the map are at proportionally correct distances from the center point, and that all points on the map are at the correct azimuth (direction) from the center point. A useful application for this type of projection is a polar projection which shows all meridians as straight, with distances from the pole represented correctly.

<span class="mw-page-title-main">Sinusoidal projection</span> Pseudocylindrical equal-area map projection

The sinusoidal projection is a pseudocylindrical equal-area map projection, sometimes called the Sanson–Flamsteed or the Mercator equal-area projection. Jean Cossin of Dieppe was one of the first mapmakers to use the sinusoidal, using it in a world map in 1570.

<span class="mw-page-title-main">Bonne projection</span>

The Bonne projection is a pseudoconical equal-area map projection, sometimes called a dépôt de la guerre, modified Flamsteed, or a Sylvanus projection. Although named after Rigobert Bonne (1727–1795), the projection was in use prior to his birth, in 1511 by Sylvanus, Honter in 1561, De l'Isle before 1700 and Coronelli in 1696. Both Sylvanus and Honter's usages were approximate, however, and it is not clear they intended to be the same projection.

<span class="mw-page-title-main">Bottomley projection</span> Pseudoconical equal-area map projection

The Bottomley map projection is a pseudoconical equal area map projection defined as:

<span class="mw-page-title-main">Van der Grinten projection</span> Compromise map projection

The van der Grinten projection is a compromise map projection, which means that it is neither equal-area nor conformal. Unlike perspective projections, the van der Grinten projection is an arbitrary geometric construction on the plane. Van der Grinten projects the entire Earth into a circle. It largely preserves the familiar shapes of the Mercator projection while modestly reducing Mercator's distortion. Polar regions are subject to extreme distortion. Lines of longitude converge to points at the poles.

<span class="mw-page-title-main">Space-oblique Mercator projection</span> Map projection

Space-oblique Mercator projection is a map projection devised in the 1970s for preparing maps from Earth-survey satellite data. It is a generalization of the oblique Mercator projection that incorporates the time evolution of a given satellite ground track to optimize its representation on the map. The oblique Mercator projection, on the other hand, optimizes for a given geodesic.

<span class="mw-page-title-main">Hammer projection</span> Pseudoazimuthal equal-area map projection

The Hammer projection is an equal-area map projection described by Ernst Hammer in 1892. Using the same 2:1 elliptical outer shape as the Mollweide projection, Hammer intended to reduce distortion in the regions of the outer meridians, where it is extreme in the Mollweide.

<span class="mw-page-title-main">General Perspective projection</span> Azimuthal perspective map projection

The General Perspective projection is a map projection. When the Earth is photographed from space, the camera records the view as a perspective projection. When the camera is aimed toward the center of the Earth, the resulting projection is called Vertical Perspective. When aimed in other directions, the resulting projection is called a Tilted Perspective.

<span class="mw-page-title-main">Equidistant conic projection</span> Conic equidistant map projection

The equidistant conic projection is a conic map projection commonly used for maps of small countries as well as for larger regions such as the continental United States that are elongated east-to-west.

<span class="mw-page-title-main">Eckert IV projection</span> Pseudocylindrical equal-area map projection

The Eckert IV projection is an equal-area pseudocylindrical map projection. The length of the polar lines is half that of the equator, and lines of longitude are semiellipses, or portions of ellipses. It was first described by Max Eckert in 1906 as one of a series of three pairs of pseudocylindrical projections. Within each pair, meridians are the same whereas parallels differ. Odd-numbered projections have parallels spaced equally, whereas even-numbered projections have parallels spaced to preserve area. Eckert IV is paired with Eckert III.

<span class="mw-page-title-main">Eckert II projection</span> Pseudocylindrical equal-area map projection

The Eckert II projection is an equal-area pseudocylindrical map projection. In the equatorial aspect the network of longitude and latitude lines consists solely of straight lines, and the outer boundary has the distinctive shape of an elongated hexagon. It was first described by Max Eckert in 1906 as one of a series of three pairs of pseudocylindrical projections. Within each pair, the meridians have the same shape, and the odd-numbered projection has equally spaced parallels, whereas the even-numbered projection has parallels spaced to preserve area. The pair to Eckert II is the Eckert I projection.

<span class="mw-page-title-main">Hammer retroazimuthal projection</span> Retroazimuthal map projection

The Hammer retroazimuthal projection is a modified azimuthal proposed by Ernst Hermann Heinrich Hammer in 1910. As a retroazimuthal projection, azimuths (directions) are correct from any point to the designated center point. Additionally, all distances from the center of the map are proportional to what they are on the globe. In whole-world presentation, the back and front hemispheres overlap, making the projection a non-injective function. The back hemisphere can be rotated 180° to avoid overlap, but in this case, any azimuths measured from the back hemisphere must be corrected.

<span class="mw-page-title-main">Armadillo projection</span> Compromise map projection

The armadillo projection is a map projection used for world maps. It is neither conformal nor equal-area but instead affords a view evoking a perspective projection while showing most of the globe instead of the half or less that a perspective would. The projection was presented in 1943 by Erwin Raisz (1893–1968) as part of a series of "orthoapsidal" projections, which are perspectives of the globe projected onto various surfaces. This entry in the series has the globe projected onto the outer half of half a torus. Raisz singled it out and named it the "armadillo" projection.

<span class="mw-page-title-main">American polyconic projection</span> Map projection historically used for maps of the United States

In the cartography of the United States, the American polyconic projection is a map projection used for maps of the United States and its regions beginning early in the 19th century. It belongs to the polyconic projection class, which consists of map projections whose parallels are non-concentric circular arcs except for the equator, which is straight. Often the American polyconic is simply called the polyconic projection.

References

  1. Snyder, John P. (1993). Flattening the Earth: Two Thousand Years of Map Projections. ISBN   0-226-76747-7..
  2. Snyder, John P. (1989). An Album of Map Projections (PDF). Vol. U.S. Geological Survey Professional Paper 1453. United States Government Printing Office. Archived (PDF) from the original on 2012-01-19.