Talk:Mercator projection

message: @Erickespinal26 can you explain the reasoning for including this Reddit image?  It seems to accomplish the same thing as the animated image already shown, but is much worse because it's hosted externally.  I can see that it might make sense to replace the animated image if the Reddit one were uploaded to the Commons, but we hardly need both, do we? Justin Kunimune (talk) 11:54, 20 September 2023 (UTC)
thread_title:  Size distortion image 

message: My impression (not knowing much about this) is that the Mercator projection emerged as part of a historical process of developing maps for sailing based on following "rhumbs" (i.e. bearings, found by astronomical observation or a magnetic compass). It seems like it would be worth discussing this at least a little bit for context, and linking to Portolan chart and rhumbline network, etc. One of the reasons that the speculation about Song Dynasty star charts using the Mercator projection are so implausible is that from what I can tell Chinese navigation did not have the same historical or technological context/process [the compass as a needle in a bowl of water was known in Song China, but I'm not sure if it was being widely used by sailors, and I'm not sure if there were any maps with windrose lines all over them] and star charts per se have no particular reason to make rhumb lines straight. Does anyone have any favorite sources about this topic, or enough knowledge to summarize off the top of their head? –jacobolus (t) 17:39, 19 November 2023 (UTC)
replies: text: I imagine you could answer this easily? Strebe (talk) 21:49, 23 May 2024 (UTC)
thread_title:  Shouldn't the history section start with the context of Portolan charts? 

message: User:Kencf0618 is insisting on including an image from a website that generates non-coaxial Mercator projections. These are not relevant to understanding the standard Mercator projection and confuse the issues with Mercator by appearing completely different. The author’s argument is that it demonstrates the distortions in Mercator, but there are already several pictures that serve that purpose. If there were actually any applications of such variants of Mercator, they would warrant inclusion in a separate section, right after Web Mercator. But so far as I know they’re just a toy and the author has not presented such uses. Since these variants are confusing, uneducational, non-standard, and not useful, they are irrelevant and I do not think they belong in this article. Andy Anderson 17:37, 23 May 2024 (UTC)
replies: text: I disagree that the topic is irrelevant. In concept, it is a good idea and illustrates the inflation problem evocatively. Unfortunately, (1) this is WP:OR and therefore not allowed, including the external link at the bottom; (2) the wording is invented: there is no such thing as “coaxial”, let alone “non-coaxial” in this context; and (3) the implementation is faulty and confusing: the lobes at the extreme level of distortion are not a feature of the Mercator projection. Strebe (talk) 18:34, 23 May 2024 (UTC)
replies: text: I applied the term “co-axial” to indicate that the axis of the cylinder of projection is different than the Earth’s axis. Seemed more descriptive than “Mercator Extreme” :-). Andy Anderson 19:12, 23 May 2024 (UTC)

text: I see now that the “lobes” are intersecting streets stretched nearly infinitely. That leaves only the WP:OR problem. Also, however, the image as given is unacceptably large for an article. Strebe (talk) 21:54, 23 May 2024 (UTC)
replies: text: It takes a while for the lobes to sink in. The Mercator projection is asymptotic such that the closer you get to infinity, the bigger things get. States become as large as continents, then blocks, then individual buildings. This exponential distortion of familiar terrain hits like the blank, white bar of Antarctica does not. And it's all geometry, straightforward. kencf0618 (talk) 22:29, 23 May 2024 (UTC)

text: The term for “non-coaxial” in this context is “oblique”. As for the link at the bottom of the page, it falls squarely in the WP:NOBLOGS prohibition. The WP:OR assessment is more complicated. I don’t know how making it interactive helps. Strebe (talk) 01:33, 24 May 2024 (UTC)

text: –jacobolus (t) 06:09, 24 May 2024 (UTC)

text: I don't understand what point you are trying to make. –jacobolus (t) 13:57, 24 May 2024 (UTC)

text: Nukemap is not relevant to justifying the inclusion of “Mercator: Extreme”: Nukemap has an article because it is based on WP:RELIABLE sources and found to be WP:NOTABLE, not because of subjective statements about how useful it is. If you find other content or articles that do not meet minimal standards, those do not amount to an argument to permit even more. kencf0618, you have ignored the WP:NOBLOGS argument, which the link to your site seems to me to be in clear violation of. Unless other editors contradict that, I will delete it. With respect to the illustration, don’t get me wrong: I like it for the reasons I gave. However, its qualifications are in a gray zone, having no formal validation for correctness. It does help that the code is available for inspection, which is what puts it into the “maybe” category for me. My opinion, as just an editor, is that the image, if it to be included, needs to be of similar size to any other on the page, needs to crop out the application UI elements, and needs to move the informative text into a much more compressed space. Andy Anderson, would those improvements, along with this discussion, allay your concerns? Strebe (talk) 17:33, 24 May 2024 (UTC)
replies: text: Agreed that the image needs to be smaller, if that were the only issue I would have fixed it myself. As I said previously, because it is not standard Mercator and is not even recognizable as Mercator without some thought, it needs to be in its own section, "Oblique Mercator” as you suggest, with its own informative description, and really should include some justification of “why bother”. I know there are a lot of map projections out there that are not commonly used, but they were typically developed for particular purposes, e.g. transverse Mercator which is useful in the region of particular meridians. Andy Anderson 17:55, 24 May 2024 (UTC)
replies: text: Oblique Mercator with the code it is. Arc de Triomphe, anyone? kencf0618 (talk) 20:33, 24 May 2024 (UTC)
thread_title:  Irrelevance of Non-Coaxial Mercator 

message: The section Properties begins with a very nice diagram illustrating the different possible orientations of the cylinder axis. It uses the term "standard" to refer to the commonly understood representation of the Mercator projection with the Earth and cylinder axes coincident. Jacobolus wants to use instead the synonym "normal" that he asserts is the proper technical term for this orientation. I can find both terms in use, e.g. . However, the paramount consideration here is user understanding, and using a different term from the one in the diagram will certainly be confusing. I have no other objection to the use of "normal", but if it is to be used then the diagram must be changed at the same time. That is Jacobolus' responsibility. -- Andy Anderson 16:42, 26 May 2024 (UTC)
replies: text: Agreed. Strebe (talk) 18:46, 26 May 2024 (UTC)

text: @AndyAnderson If you want feel free to remove or fix the diagram. Repeated addition of "standard" all over the text is awkward and unhelpful. It should say something like "in normal aspect" (or if you demand "in standard aspect" is probably an okay substitute), once, at the top of the section. –jacobolus (t) 06:30, 27 May 2024 (UTC)
replies: text: When the paragraph only refers to the "standard" Mercator but not to the other variants its use is not only helpful but necessary. Andy Anderson 15:57, 27 May 2024 (UTC)
replies: text: @AndyAnderson You need to immediately desist from edit warring, or you can be temporarily blocked from this page. See Wikipedia:Edit Warring. If you like we can revert to the version from a few days ago while this gets hashed out. –jacobolus (t) 18:03, 27 May 2024 (UTC)
replies: text: @Jacobolus -- You are the one who keeps changing it back, without responding to my clear rationale as described in my changes or here in the Talk. So who is the one who is “warring”? -- Andy Anderson 18:12, 27 May 2024 (UTC)
replies: text: The standard protocol when there is a dispute based on new changes is to revert the changes causing the dispute and have a discussion, see WP:BRD. What is not okay is repeatedly reverting to enforce your preferred new version that other editors disagree with. My offer here is that if you prefer we can go back to a stable version of the text of the section from a week ago or whenever. –jacobolus (t) 18:58, 27 May 2024 (UTC)
replies: text: I changed the diagram to say "normal".  Does this address all parties' concerns?  Justin Kunimune (talk) 23:43, 27 May 2024 (UTC)
replies: text: Thanks Justin. –jacobolus (t) 02:14, 28 May 2024 (UTC)

text: @Jacobolus If you pay attention to the Talk, you will see that it was only you, me, and streib commenting on this, and streib agreed with me. Andy Anderson 00:27, 28 May 2024 (UTC)
replies: text: That's fine. Wikipedia is about building consensus, and edit warring behavior is disruptive of that process. Every editor is encouraged to make "bold" edits which they believe are improvements, but when there is any kind of dispute where two or more editors disagree about the best outcome, the common approach, unless there is some overriding concern (copyright violation, defamation, ...), is to revert new controversial changes and then discuss them on the talk page until consensus can be reached. This substantially reduces squabbling and finger pointing while leaving time for discussion. Consensus is about dialog and compromise, and is not a vote. (Aside: I read the recent discussion carefully, and don't need help "paying attention".) –jacobolus (t) 02:13, 28 May 2024 (UTC)
thread_title:  Terminology in section Properties 

message: This section is not accurate. The mentioned uses of the transverse Mercator are all against the ellipsoidal form, not the cylindrical form that is the topic of this article. The only mention of ellipsoidal form is about the equatorial aspect. The same goes for the oblique form. There are no common uses for spherical, non-equatorial Mercator. Strebe (talk) 19:11, 26 May 2024 (UTC)
replies: text: The relevant section to add vis-a-vis "extreme mercator" is something like "Artistic uses", and we can link Pérez-Duarte & Swart 2013 as a source, and maybe some other sources of people doing stuff like projecting panoramic images using the Mercator projection, etc. –jacobolus (t) 06:35, 27 May 2024 (UTC)

text: This reversion ignored the reasons I made for the change. In general, I am dissatisfied with User:AndyAnderson's practice of hasty reversion and apparent WP:OWN behavior, particularly as exercised against User:Jacobolus. I am at the point of considering calling in admin help. As I pointed out, we already have articles that address the ellipsoidal versions, which are the only versions used in practice. Meanwhile, the section talks about what are ellipsoidal uses for the Mercator projection without even stating that. The reasons AndyAnderson gives for the reversion make no sense to me. “Along the meridian” means “north-south”; if for some reason AndyAnderson believes the typical reader is ignorant of that, then I think we could work out a suitable text without leaving my criticisms unaddressed. If the text needs a wikilink for national grid systems or such, that, too, could easily be arranged. These sorts of niggles are not normally the subject of reversions, particularly when the people involved are all experienced editors and are knowledgeable about the subject. Strebe (talk) 18:11, 28 May 2024 (UTC)
replies: text: I don't think we need admin help. While AndyAnderson's account was created a long time ago, they aren't a tremendously heavy Wikipedia editor, so probably (I didn't check) haven't been involved in too many recent disputes. I think we can work this out with talk page discussion. –jacobolus (t) 18:15, 28 May 2024 (UTC)
thread_title:  Transverse and oblique Mercator