Does anyone know why Google insists on Mercator projection? I guess that it makes the implementation bit simpler, but on the other hand you'd imagine that if anyone then Google would have the resources to use some more reasonable projection for greater good.
"Hi John - Thanks for the feedback. Maps uses Mercator because it preserves angles. The first launch of Maps actually did not use Mercator, and streets in high latitude places like Stockholm did not meet at right angles on the map the way they do in reality. While this distorts a 'zoomed-out view' of the map, it allows close-ups (street level) to appear more like reality. The majority of our users are looking down at the street level for businesses, directions, etc... so we're sticking with this projection for now."
Yes, there are two properties that are important for Google Maps:
1. Mercator is conformal, which means angles are preserved. So if you zoom into any small part of the map, it will look right. Equal-area maps distort angles.
2. North is always in the same direction—up. Together with the conformal property, it means that all directions are preserved: North, South, and everything else.
The primary use case for Google Maps is not to show the whole world at once, rather it is targeted at street-level mapping. Hence, Mercator is an ideal choice.
Of course, Google Maps isn't subject to the same limitations as paper maps – the projection could vary with both position and zoom level.
There are design and technical concerns, but they are not insurmountable. After all, if you ignore tilting then Google Earth is essentially a dynamically redrawn (position and scale variant!) planar map projection. With the proliferation of vector maps on mobile and WebGL in the browser, it seems like a solution could be found.
Interesting. From this description I would expect that mercator would always agree with lat/long in terms of "Is X North or South of Y" questions.
However, Albany (Australia) appears to be South of Melbourne when in its starting position on this map (inverted when moved to its correct position.) How is this possible?
As far as I can tell that actually could work very well, though the implementation might be quite difficult: 15 different zoom levels (I think) that google uses probably wouldn't be enough to make transitions between each seamless, requiring client side scaling during the zoom animations (which will either make the images slightly blurry or require loading higher resolution images).
The thing is, Mercator was never actually intended to be used as a map, per se. What it was supposed to be used for was a navigation chart, and it's extremely useful in that context: straight lines on the map correspond to straight lines in the real world, the compass directions are the same no matter where you look, and so on. Other projections distort these things, and there can be good reasons to do that depending on what exactly one wants to do. If you're trying to find single points, it really doesn't matter so much. But when the reason you're using the map is to find a route between Point A and Point B, Mercator really is the most reasonable projection for the job.
Yes, you are correct, however that's a different sort of straight line: it is the shortest distance between two points, but it isn't the most easily navigable line. The navigable ones are lines of constant bearing, since a ship could/can set their compass and make adjustments to hold it "straight" rather than having to do the computations required to follow a great circle.
Mercator has loads of advantages which other projections don't- most importantly that angles are preserved and distances are not distorted when zoomed in. It only really has one disadvantage - that in a fully zommed out view, the poles appear bigger. That's not a biggie. You can find world maps in other projections easily on other sites.
I understand that Mercator isn't the most accurate representation, but seriously, "greater good?" There are a lot of things that I think Google can do "for greater good," and changing how they show a map isn't even in the first hundred pages.
Most people don't own an Atlas anymore. In the public consciousness Google Maps is the world map. If choice of map projection is important anywhere (which is debatable), it's important on Google Maps.
And remember: you can always fail over to Mercator.
Map projections are part of the technological infrastructure of the world. Most people shouldn't have to worry, but someone needs to. What about calculating missile range? Or designing a tunnel that needs to be accurate to 1cm. Are your GPS surveys out by 30cm because you used a system that ignores continental drift. Or placing an oil rig in the wrong place in the sea due to a poor projection choice.
Another advantage of Mercator is that if you display the map from latitudes of about -85 degrees to +85 degrees you end up with a perfect square, which makes chopping the map into tiles nice and easy.
TL;DR The Mercator projection is a solution to a problem that does not exist in Google Earth.
Projections, Mercator included, are ways to map a 3D shape (the globe) onto a static 2D surface (a map). Google Earth uses a dynamic 2D surface (a screen) to display a changing view of a 3D object. See TL;DR.
I think it's got to do with preserving north south east and west angles. Also, the distortion is only noticeable when you're zoomed out. When zoomed in most things are in relative proportion to each other.
