Gall–Peters projection

The Peters projection is a historian Arno Peters in 1974 published by the card network design, a variant of the equal-area cylindrical design with two length-preserving parallel circles, which is identical to Gall's orthographic projection, the Scottish cleric James Gall had already published in 1855. Unlike Gall's first publication generated Peters publication, who had developed the new card network design independent, sustained attention and led to an increased use of the network design, which is now referred to as Gall- Peters projection.

Reason for the, albeit limited, enforcement was cited by Peters historical- political motivation for the development of the imaginary by him especially for World Map projection: The lying is usually closer to the equator Third World countries should face lying in higher northern latitudes industrialized countries are presented in the correct aspect ratio ( surface fidelity ), which is not the case with Peters as " Eurocentric " can actually be used for comparison, cylindrical projections, the Mercator projection, or square planar map. Given the ambition, the Peters projection is the only right, a partly heated controversy developed with representatives of cartography, the substantially contested that cylindrical projections for geographic world maps are suitable and at the Peters projection particularly criticized the substantial distortions. The measures proposed by cartographers area preserving alternatives, pseudo cylindrical or similar projections, leading to approximately elliptical world map, actually urged long-term use of the Peters projection back.

Properties of the projection

Peters projection may be considered as a projection onto a cylinder, which intersects the ground at 45 ° latitude. She's surfaces, position and axis faithful, that is, that all surfaces are mapped to the same scale and that loci of equal width and length are on horizontal and vertical lines. However, it is neither length nor form- and angle-preserving: squares or circles are preserved only at 45 ° latitude, the equator, they are in contrast with north -south and east-west dimensions of 1.4 and 0.7, so an aspect ratio of 2:1, pictured. At 60 ° latitude, the ratio is reversed in Iceland reached the distortion 1:3 and then increases very fast, the contour of Spitsbergen is no longer recognizable.

Controversy on the application

Following the publication it came to heated debates in which of established cartographers particularly Peters ' naive approach and technical errors were criticized, while proponents championed the general use of its projection and attributed her part also properties that they had not. The conformal but strong surface distorting Mercator projection was accused of shifting " the proportions in favor of the northern hemisphere and thus also for the benefit of the white race ". The unsuitability of 1569 expressly and exclusively "ad usum navigantium " ( for navigation purposes ) published direction loyal Mercator projection for geographical maps, however, was already Mercator himself perfectly clear, so that they consequently never been applied in his extensive atlas of 1595. According argued established cartographers, that criticism of the problem pass by, as for the intended purpose much more appropriate card network designs - would be available - both as the Mercator as well as the Peters projection.

Application and alternatives

The Peters projection was used in the 1980 North-South Report and adopted by several organizations for their public relations. It was occasionally used by various organizations for world maps, but has not generally enforced. She also became the basis of the Peters Atlas.

Most today world maps are used with non- rectangular base. The task of the axis loyalty allows so demanded by Peters surface fidelity at much lower angle and shape distortions: The Mollweide that has point-like poles, can be used in single or in the form zerlappten by JP Goode. The latter scored particularly low distortion, but this involves the connection of the card partially lost. If zonal considerations are not relevant and thus also the position loyalty can be abandoned, the use of a hammer - Aitov projection with curved latitudes and thereby also reduced form of distortion is possible. The situation in turn loyal Eckert IV projection appears similar to the Goode - Zerlappung less crowded together by linear poles in this area. Often, the application is also angle - Tripel projection angle of Oswald, but is no longer exactly equal area, but is applied balancing. The same is true for the frequently used in the U.S. Robinson projection, which in turn maintains the position of loyalty and this bought with larger distortions.

Mollweide equal area positional accuracy

Zerlappung, here Goode Homolosine projection, planes and positional accuracy

Hammer Aitov projection equal area

Eckert IV equal area positional accuracy

Angle Tripelprojektion intermediary

Robinson projection intermediary positional accuracy