Talk:Universal Transverse Mercator coordinate system

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On 15 September 2025, it was proposed that this article be moved to Universal Transverse Mercator. The result of the discussion was not moved.

a and A are used interchangeably in formulas

In the section about simplified formulas, at the end of the page, a is defined as the Earth radius and used in the first four formulas. The next ones use A which is not defined and I assume is the same as A. This should be clarified or corrected. Pot (talk) 17:08, 18 June 2021 (UTC)[reply]

Like many other variables in the formulae, 'A' is an intermediate value used in later calculations. It is not 'a', as should be clear from its definition in terms of 'a'. Intermediate values are normal in mathematical descriptions. Strebe (talk) 18:06, 18 June 2021 (UTC)[reply]

why the UTM system divides the global into sixty zones?

. 197.186.16.71 (talk) 17:09, 12 January 2023 (UTC)[reply]

As the article explains:

By using narrow zones of 6° of longitude (up to 668 km) in width, and reducing the scale factor along the central meridian to 0.9996 (a reduction of 1:2500), the amount of distortion is held below 1 part in 1,000 inside each zone. Distortion of scale increases to 1.0010 at the zone boundaries along the equator.

— Universal Transverse Mercator coordinate system § UTM zone

It is a trade-off between convenience of covering a reasonable area per "slice" v distortion. --𝕁𝕄𝔽 (talk) 19:09, 12 January 2023 (UTC)[reply]

Requested move 15 September 2025

The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this discussion.

The result of the move request was: not moved. After this RM was relisted twice, and no comments since 24 September, I don't see a clear consensus to rename this page. (closed by non-admin page mover) JuniperChill (talk) 21:26, 7 October 2025 (UTC)[reply]

Universal Transverse Mercator coordinate system → Universal Transverse MercatorUniversal Transverse Mercator – Common name, as per lead. fgnievinski (talk) 07:23, 15 September 2025 (UTC) — Relisting. Jeffrey34555 (talk) 18:14, 21 September 2025 (UTC) — Relisting. TarnishedPath^talk 11:52, 29 September 2025 (UTC)[reply]

oppose. Every reference I look at refers to it as Universal Transverse Mercator grid or Universal Transverse Mercator coordinate system when introducing the topic. (USGS uses both.) Most references do not elide the “coordinate system” or “grid” except after first usage, where they often abbreviate to UTM. Rarely do I see the unabbreviated Universal Transverse Mercator without “grid” or “coordinate system” in any context. Strebe (talk) 16:24, 15 September 2025 (UTC)[reply]
You're right in that the longer name is the proper name. But I still think the shorter name is more common. Plus, we need consistency with Modified transverse Mercator, Irish Transverse Mercator, Israeli Transverse Mercator, Jordan Transverse Mercator, etc. fgnievinski (talk) 20:24, 15 September 2025 (UTC)[reply]

I don’t find any reliable source that says the shorter form is more common; nor do I see it more commonly in the literature. I think the solution to “consistency” is to fix the other examples. Strebe (talk) 20:57, 15 September 2025 (UTC)[reply]

Would you accept adopting the suffix "grid" throughout? It's more succinct that "coordinate system". fgnievinski (talk) 21:40, 15 September 2025 (UTC)[reply]

That certainly works for UTM, and spot checking one or two of the others suggests it works for them as well, but we probably should confirm somehow. Thanks. Strebe (talk) 21:51, 15 September 2025 (UTC)[reply]

- Support. The shorter name is unambiguous. —Kodiologist (t) 12:34, 24 September 2025 (UTC)[reply]

Oppose as the coordinate system is an application of UTM, not UTM itself. However, Universal Transverse Mercator redirects here, there is no dedicated article about UTM, so the solution may well be to make this article begin with a description of UTM and then spend most of the article on its primary application. So the desired result would seem achievable albeit with a bit more work.
- (Although I like Universal Transverse Mercator grid for its brevity, the term 'grid' for mapping seems to be deprecated? The most National Grids seem to be enrgey distribution grids: use of the term in cartography may be WW2 slang as the National Grid (disambiguation) page uses National grid reference system – which redirects to Projected coordinate system. There is no National grid (mapping) article. ) --𝕁𝕄𝔽 (talk) 13:34, 24 September 2025 (UTC)[reply]
What would be "UTM itself"? The secant transverse Mercator projection in a single 6° longitudinal zone? fgnievinski (talk) 23:04, 24 September 2025 (UTC)[reply]

Note: WikiProject Maps has been notified of this discussion. TarnishedPath^talk 11:54, 29 September 2025 (UTC)[reply]

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Simplified formulae - UTM to Longitude/Latitude

In the introductory part of the simplified formulae, it is stated that angles are expressed in radians. The expression of the reference longitude for the UTM zone uses instead a formula which clearly gives a value in degrees, namely $\lambda _{0}=\mathrm {Z} \mathrm {o} \mathrm {n} \mathrm {e} \times 6^{\circ }-183^{\circ }\,$ . Using this value without converting it in radians would lead to an incorrect value for the longitude $\lambda$ computed in the line immediately following. The formula for $\lambda _{0}$ is simple and straightforward so I'm not suggesting to modify it in a way that could hide the geometric reasons behind it. However, there should be an indication that the value so obtained is in degrees and should be converted in radians before using it in the calculation of $\lambda$ . I'd suggest $\lambda _{0}=\pi \,{\frac {\mathrm {Z} \mathrm {o} \mathrm {n} \mathrm {e} \times 6^{\circ }-183^{\circ }\,}{180^{\circ }}}$ or something similar. Maredovir (talk) 07:09, 24 October 2025 (UTC)[reply]

There isn’t any need for radians, it seems to me. The latitude is always processed via trig functions, with unitless results. The sole exception is in the calculation of the latitude in the inverse formulation, where the summation is in radians. Because UTM zones are based on degrees, shouldn’t we just state that everything is in degrees, and fix that one formula? I doubt anyone sophisticated enough to program those formulas need to be warned that most trig implementations only take radians, but we could add that warning into the units description. Strebe (talk) 16:38, 24 October 2025 (UTC)[reply]

The use of radians in the inverse formulae probably follows from the definition of ξ and η in the intermediate calculations. I agree with you that using latitudes and longitudes expressed in degrees can be handy. However most of the references I've seen on this matter express the angles in radians, so keeping a general consistency could also be advisable. Anyway, I am not an expert on the field, so I'd prefer to leave the choice to you... Maredovir (talk) 17:18, 24 October 2025 (UTC)[reply]