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I think this is an externally visible link: http://productforums.google.com/forum/#!topic/maps/A2ygEJ5eG-o/discussion http://productforums.google.com/forum/#!to
by jemfinch 14y ago
I think this is an externally visible link: http://productforums.google.com/forum/#!topic/maps/A2ygEJ5eG-o/discussion http://productforums.google.com/forum/#!topic/maps/A2ygEJ5eG... . It's the answer I received when I filed an internal bug on this.
"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."
- jasondavies 14y agoYes, 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.
- deleted 14y ago[deleted]
- schiffern 14y agoOf 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.
- finnw 14y agoInteresting. 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?
- a3_nm 14y agoNot sure if this makes sense, but couldn't they have different projections for different zoom levels?
- benjoffe 14y agoAs 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).
- deleted 14y ago[deleted]
- rjh29 14y agoYes, and considering that Google Maps can use WebGL with vector graphics, it would be seamless.
- jasondavies 14y agoYes, e.g. http://cartography.oregonstate.edu/demos/CompositeMapProjection/ http://cartography.oregonstate.edu/demos/CompositeMapProject...
- opinali 14y agoI see a huge, annoying jump into and out of Mercator.
- vanderZwan 14y agoA bit of tweening animation should be able to fix that though.
- RobotCaleb 14y agoThat's really cool. Thanks for sharing.
- 7952 14y agoAlso, the math required to convert lat/lon to web Mercator is fairly light and not resource intensive.