Talk:Map projection

Classification of old maps without projection?

In Commons we have problem with old maps and their projections. Wise advices will be needed in here: Commons:Commons:Categories for discussion/2018/01/Category:Maps with unidentified projection--Estopedist1 (talk) 10:39, 29 November 2021 (UTC)

Gigantic

"The projections are described in terms of placing a gigantic surface in contact with the Earth" - violation of NPOV? Who defined the surface as gigantic? Is that encyclopedic? Euro2023 (talk) 23:54, 9 January 2023 (UTC)

Do you believe that the use of English adverbs and adjectives is automatically unencyclopedic, and that encyclopedic language should be limited only to nouns, verbs, and connecting words? —David Eppstein (talk) 00:06, 10 January 2023 (UTC)

I changed the wording to convey the same meaning. Gigantic is relative, and map projection is not only limited to the Earth. GeogSage ^{(⚔Chat?⚔)} 00:23, 10 January 2023 (UTC)

light shining through a globe

"If maps were projected as in light shining through a globe onto a developable surface, then the spacing of parallels would follow a very limited set of possibilities." - How that? Why should there be a limitation? Is there projection of a particular point on a surface that cannot be reached by "light shining through a globe"? Euro2023 (talk) 15:45, 10 January 2023 (UTC)

The set of projections defined by projective geometry is grossly limited compared to the the set that is possible from more general mathematical transformations permitted in the common definition of cylindrical projection. Strebe (talk) 19:24, 10 January 2023 (UTC)

"in the common definition of cylindrical projection" isn't contained in the claim, or the text next to it, that I copied from the article. And where is the evidence that such a "common definition of cylindrical projection" exists? https://en.wikipedia.org/w/index.php?search=%22common+definition+of+cylindrical+projection%22&title=Special:Search&profile=advanced&fulltext=1&ns0=1 : "There were no results matching the query." Euro2023 (talk) 19:36, 10 January 2023 (UTC)

The common definition, whatever it is or isn’t, does encompass the Mercator projection, as per all the literature in existence. Meanwhile, the Mercator projection cannot be represented just by “light shining through a globe onto a developable surface”. Therefore, given that we have an example (and scores more) of cylindrical projections that cannot be represented by “light shining through a globe onto a developable surface”, the statement is fine. Strebe (talk) 21:33, 10 January 2023 (UTC)

Although this article does address the position of the theoretical light source, as far as I can see (as of 2026-1-15) this does not appear to be until well over half way through the article (section "azimuth…"). As far as I can tell, the assumption for most of the article is that the light source is at the centre of the globe - or the question is not addressed at all. I feel this - a rather fundamental aspect of the subject - should be, in a clear manner. addressed much earlier in the discussion.G6JPG (talk) 17:16, 15 January 2026 (UTC)

“Light shining through a globe” is not relevant to map projections in general, as per the earlier comments in this thread. It is little more than a conceptual device, and even then, of debatable value. Strebe (talk) 17:36, 15 January 2026 (UTC)

WikiProject

I have created a proposal page for Map projections. Please feel free to add your name to the support section, discuss, disseminate, and otherwise edit. Thanks. Strebe (talk) 01:26, 12 January 2023 (UTC) @Justinkunimune:@GeogSage:@Elphion:@Fgnievinski:@Alvesgaspar:@Paul Koning:@Peter Mercator:@EdwardLane:@Jacobolus:@Apocheir:

See also , ,

See also, geoinformatics has 2 commas in a row separated by a space. I can't figure out if there's something missing or how to remove one of them. 82.135.221.10 (talk) 15:41, 7 July 2024 (UTC)

Fixed, thanks! The extra commas were part of the geoinformatics article's short description. Just plain Bill (talk) 16:02, 7 July 2024 (UTC)