Talk:Equirectangular projection

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[edit] Questions

Who invented it ? When was it first used? What advantages does it give over other projections?

Lumos3 09:24, 31 October 2006 (UTC)

[edit] left and right side

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)

The use of "180" and "360" is also questionable. The left hand arguments are radians, not degrees. mdf 21:53, 31 October 2006 (UTC)

[edit] image size

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 image -- the 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)

[edit] Mercator

Isn't this just the Mercator projection? Steinbach (fka Caesarion) 22:31, 31 October 2006 (UTC)

No, in a mercator projection, lines of latitude are closer together at the equator than at the poles. In an equirectangular projection, they are all equidistant. On a mercator projection, land masses near the poles, like Greenland, have their shape fairly accurately represented, but on an equirectangular projection, they are squished. Compare Image:Normal Mercator map 85deg.jpg with Image:Equirectangular-projection.jpg to see the difference.
On the other hand, sizes are more distorted in a Mercator projection, as you can see by comparing Greenland with Africa—the latter is fourteen times the size, but appears smaller. However, accurate representation of sizes is not the goal of either projection.
Foobaz·o< 15:52, 1 November 2006 (UTC)

[edit] Distorted earth?

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)

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)

[edit] Definition question

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