An equal-area map projection for irregular objects

Icarus ◽  
2005 ◽  
Vol 175 (2) ◽  
pp. 382-389 ◽  
Author(s):  
M.G. Berthoud
Keyword(s):  
Author(s):  
Doina Vasilca

In this article are presented the very first maps realised in a systematic way in order to determine the boundaries and register the properties of the Kingdom of Romania, at a scale of 1:20,000 in the equal-area pseudoconical Bonne projection. This projection was not applied in a uniform way for the whole territory of the country, but differently for the areas situated east and west of the Zimnicea meridian, respectively. For each of these two zones I have shown the peculiarities of applying the Bonne projection. furthermore, I explained in detail the means of establishing the nomenclatures of the maps at a scale of 1:20,000, but also at smaller scales, 1:50,000, 1:100,000 and 1:200,000. Since the analyzed map projection preserves area measurements, I verified this property on five maps at the scale of 1:20,000, chosen from both zones. Results obtained for the zone east of the Zimnicea meridian showed a 0.0005% difference, falling within the tolerated error, but for the maps situated west of the Zimnicea meridian, the area differs by about 3%. I have proved that this large difference in the area of the analyzed maps, identified at the eastern extremity of the mapped zone, is due to the fact that they are not actually bordered by the Zimnicea meridian, but by a line related to the Cartesian system used. The Bonne projection maps made for the entire Romanian Kingdom by specialists of the Romanian Army nowadays possess significant historical importance, both in terms of mapping and cadastre.


2000 ◽  
Vol 27 (2) ◽  
pp. 91-100 ◽  
Author(s):  
Yang Cheng ◽  
Jean J. Lorre
Keyword(s):  

2019 ◽  
Vol 18 (32) ◽  
pp. 18-32
Author(s):  
Krisztián Kerkovits

A polyazimuthal map projection is a mapping that represents parallels as non-concentric full circles on the plane. Polyazimuthal mappings are almost never mentioned in the literature dealing with map projections. However, these projections are flexible; their distortion characteristics are highly mutable. This paper expands the theory of polyazimuthal map projections. Furthermore, this study also shows the derivation for variants of this projection family (e. g. equal-area, orthogonal). The article concludes with some practical applications in the field of low-distortion map projections to demonstrate their advantages.


2019 ◽  
Vol 1 ◽  
pp. 1-1
Author(s):  
Bojan Šavrič ◽  
Bernhard Jenny ◽  
Tom Patterson

<p><strong>Abstract.</strong> The Equal Earth map projection (Figure 1) is a new pseudocylindrical projection for world maps. It is similar to the popular Robinson projection, but unlike the Robinson, it is an equal-area projection. The projection shows continental outlines in a visually pleasing and balanced way. Its equations are simple to implement and fast to evaluate. The creation of this projection was motivated by a wave of news stories about Boston Public Schools switching to maps using the Peters projection. Since its online publication in August 2018, the projection has already been adopted in various software and projection libraries and it has been featured by media outlets around the world.</p><p>This presentation will show the distortion characteristics of Equal Earth and compare them to the Robinson projection as well as a few other well-known equal-area projections. We will cover some of the published world maps that use Equal Earth and list the software that has adopted the projection. Finally, media reporting and the impact of rapid popularity via social media circulation will be discussed.</p>


2021 ◽  
Vol 20 (35) ◽  
pp. 48-69
Author(s):  
Paulo Márcio Leal de Menezes ◽  
Kairo da Silva Santos ◽  
Miljenko Lapaine ◽  
José Gomes dos Santos ◽  
Manoel do Couto Fernandes ◽  
...  

The map named Carta Geographica de Projecçaõ Espherica Orthogonal da Nova Lusitania ou America Portugueza e Estado do Brazil from 1798, together with its 1795 (?), 1797 and 1803 versions, is undoubtedly one of the cartographic monuments developed by Portuguese cartography from the late eighteenth century. Its organizer was the geographer, astronomer, and frigate captain Antonio Pires da Silva Pontes Leme, who relied on the work of 34 people, including astronomers, geographers, and engineers, who, although only mentioned in the 1798 version, contributed to the creation of all versions. All of them are similar in appearance, but differ in size, content, details, amount, and distribution of toponyms, which will be the subject of another paper. The greatest similarity, however, concerns the defined map projection. The objective of this paper is to analyse and present the possible hypotheses and conclusions about which map projection was adopted for all versions of Nova Lusitania, through the identification of characteristics that allowed to infer and prove the adopted projection. The applied methodology verified that in the bibliographic search, the information about the map structure is insufficient. An article presented by General Djalma Polli Coelho in October 1950 states that the projection suggested by its title, as orthogonal spherical, appeared to be the Sanson-Flamsteed equal-area projection. However, the expression Carta Geographica de Projecçaõ Espherica Orthogonal allows us to infer also the transverse orthographic projection. Through parameters defined for the two projections, it was possible to establish the comparative elements for a cartographic analysis, which would allow us to conclude and prove the structure adopted for the map, allowing to conclude if the adopted projection for the Nova Lusitania was an azimuthal orthographic equatorial projection, or a Sanson-Flamsteed, sinusoidal projection on the meridian 315°, defined west-east, (counterclockwise), from the El Hierro (Ferro) Island. This meridian is referenced approx. –62°39'46" off the Greenwich meridian.


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