Talk:Equirectangular projection

message: Who invented it ?
When was it first used?
What advantages does it give over other projections?
Lumos3 09:24, 31 October 2006 (UTC)
thread_title: Questions

message: The context of the subject"map projection"is that the left side are linear measures on the circle (aka "angles") and the right side are linear measures on the plane.  Do we really need to spell this out explicitly?  There are hundreds of published map projections, and if even 10% of them get documented here, things like this will get tedious real fast.  mdf 21:42, 31 October 2006 (UTC)
thread_title:  left and right side 

message: I feel the new image size is too small.  I carefully picked 512px, since it works about best without being obnoxiously large, and, frankly, there is going to be minimal text for an article on (most) map projections, but maximal imagethe subject matter is intrinsically graphical.  I "have" (such as it can be with a wiki) six other projections in, with more on the way, and a standard size is extremely important as it facilitates very easy comparison, particularly between projections of the same class.  (Example:  load up hammer projection and mollweide projection in separate tabs and you can "blink" them.)  mdf 21:48, 31 October 2006 (UTC)
thread_title:  image size 

message: :the plate carrée has become a de-facto standard for computer applications that process global maps, such as (...) Google Earth,
Is this really true? This would mean that map fragments at high latitudes are relatively compressed in north-south direction, but this seems not to be the case. 88.211.131.57 17:40, 19 July 2007 (UTC)
replies: text: You're right, Google Earth uses a orthographic projection. I don't know about the other two. Foobaz·o< 18:32, 19 July 2007 (UTC)
thread_title:  Distorted earth? 

message: what a hell is cosine doing in there? It is said, and can be seen, that the projection has "equally spaced meridians". This is simply impossible with cosine in it. If noone replies to this, I will remove it in a week. 82.207.15.147
: oh wait, I take it back. Just noticed cosine is a constant :) 82.207.15.147
I agree that the cosine term is confusing. I recommend changing the variable name.  — Preceding unsigned comment added by 192.0.232.239 (talk) 05:11, 16 October 2013 (UTC)
replies: text: It’s not a variable, so there’s no variable name to change. The formulæ are given in standard form. Just read the description. Strebe (talk) 07:08, 16 October 2013 (UTC)
thread_title:  Definition question 

message: Why is this article in panorama software category? 
While it is related, it's not a software. 
esby (talk) 12:00, 8 January 2009 (UTC)
replies: text: Equirectangular projection is a common choice in 360x180 panorama making i believe. --TiagoTiago (talk) 17:56, 18 December 2009 (UTC)
thread_title:  panorama software 

message: I will be replacing images on the various map projection pages. Presently many are on a satellite composite image from NASA that, while realistic, poorly demonstrates the projections because of dark color and low contrast. I have created a stylization of the same data with much brighter water areas and a light graticule to contrast. See the thumbnail of the example from another article. Some images on some pages are acceptable but differ stylistically from most articles; I will replace these also.
The images will be high resolution and antialiased, with 15° graticules for world projections, red, translucent equator, red tropics, and blue polar circles.
Please discuss agreement or objections over here (not this page). I intend to start these replacements on 13 August. Thank you.
Strebe (talk) 22:38, 6 August 2011 (UTC)
thread_title: Replace low-contrast images

message: The image map, as it appears in the main page, is incorrectly downsampled, missing parallels and meridians.
This is very confusing, considering that the scope of the image is to represent how the coordinates are projected. 
See here https://www.evernote.com/shard/s2/sh/7254fce9-94fd-4f4b-b337-c8380d1d3671/e3f0a8cf4dd88a722ec1ba1d281bcc01
 — Preceding unsigned comment added by Gabriel Radic (talk • contribs) 14:12, 13 September 2013 (UTC)
replies: text: I see the same problem on my desktop computer. Ironically it looks fine on my Android cellphone. Such problems are a hazard of SVG rendering. Strebe (talk) 01:05, 14 September 2013 (UTC)
thread_title:  Map image is incorrectly downsampled, missing paralleles and meridians 

message: Hello! This is a note to let the editors of this article know that :File:Equirectangular projection SW.jpg will be appearing as picture of the day on August 9, 2016. You can view and edit the POTD blurb at Template:POTD/2016-08-09. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page. — Chris Woodrich (talk) 09:39, 24 July 2016 (UTC)
thread_title:  [[:File:Equirectangular projection SW.jpg]] to appear as POTD soon 

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thread_title:  External links modified (January 2018) 

message: I can't help but notice that the Tissot's indicatrix image on this page lacks indicatrices on the International Dateline and poles - the poles being where the majority of the distortion occurs for this projection. Would anyone be averse to me inserting my own image, which both spaces out the indicatrices at high latitudes and adds indicatrices in these regions? I know technically the ellipses are supposed to be calculated at infinitesimal scale and then sized up, so it doesn't technically make sense to put them on the poles, but I feel that it's important to illustrate just how distorted the poles are.
Justin Kunimune (talk) 03:58, 16 February 2018 (UTC)
thread_title:  Adding indicatrices on the poles and International Dateline 

message: Hello! This is to let editors know that :File:Blue Marble 2002.png, a featured picture used in this article, has been selected as the English Wikipedia's picture of the day (POTD) for January 18, 2023. A preview of the POTD is displayed below and can be edited at Template:POTD/2023-01-18. For the greater benefit of readers, any potential improvements or maintenance that could benefit the quality of this article should be done before its scheduled appearance on the Main Page.  If you have any concerns, please place a message at Wikipedia talk:Picture of the day. Thank you!  — Amakuru (talk) 10:38, 31 December 2022 (UTC)
thread_title:  Featured picture scheduled for POTD 

message: Would the transformation for the plate carée version not be simply
 (x,y) = (long, lat)
?
I don't see this mentioned. Butterfly or Chuang Tzu? (talk) 02:12, 21 September 2023 (UTC)
replies: text: The equations for transforming globe coordinates to plane coordinates are mentioned in Definition § Forward.  The text notes that for Plate Carée specifically you have to set ф1 to zero, so the cosine term disappears.  Since these articles make no assumption about scale or centering there are also some R, ф0, and λ0 included. Justin Kunimune (talk) 11:29, 21 September 2023 (UTC)
thread_title:  Transformation