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Mercator Puzzle

gmaps-samples.googlecode.com

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Re: Mercator Puzzle

#31

Post by benjoffe »

a3_nm wrote: post #30
jemfinch wrote: post #24

Earlier quoted context omitted.

I think this is an externally visible link: 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 d…

Not sure if this makes sense, but couldn't they have different projections for different zoom levels?

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).

Re: Mercator Puzzle

#32

Post by donalm »

zokier wrote: post #21

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.

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.

Re: Mercator Puzzle

#33

Post by archangel_one »

sxp wrote: post #26

It's crazy how much Mercator distorts the globe. I was playing around with various map projections via WebGL shaders [1] and the size problems really stand out when the map is recentered. With modern digital maps, we should really stop using old projections that were designed to work on limited paper maps. [1] http://sxp.me/maps/ (Select equirectangular as the projection and drag the crosshairs to recenter.)

It's not really that it's old and out of date; it makes a different set of tradeoffs to other projections, and so typically looks better over small areas but isn't appropriate for a world map since the distortion becomes extreme near the poles.

Re: Mercator Puzzle

#34

Post by InclinedPlane »

zokier wrote: post #21

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.

Google Earth uses a completely different (and superior) system, however it's more resource intensive.

Re: Mercator Puzzle

#35

Post by twelvechairs »

zokier wrote: post #21

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.

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.

Re: Mercator Puzzle

#36

Post by ColinWright »

Fantastic. As a bonus side-effect, people never believe me when I tell them Australia is bigger than Europe, and this will let them play and see it for themselves.

Re: Mercator Puzzle

#37

Post by rplnt »

kenbot wrote: post #5

Bloody Mercator. Confusing generations of Australian schoolchildren since ...always. "But you said we were the biggest island!"

We've been always taught that Greenland is the biggest island. If we'd allow Australia to compete, we as well might include Eurasia :)

Re: Mercator Puzzle

#38

Post by mbq »

ColinWright wrote: post #36

Fantastic. As a bonus side-effect, people never believe me when I tell them Australia is bigger than Europe, and this will let them play and see it for themselves.

Actually, Australia is smaller than Europe (in means of the area) -- its 7.7M(km^2) to 10.2M(km^2).

Re: Mercator Puzzle

#39

Post by yohui »

flaie wrote: post #16
chii wrote: post #15

Earlier quoted context omitted.

haha, i had a different piece that was difficult - it was the saudi arabia piece. That took me forever to see.

I had a hard time finding Ukraine, Thailand was also slightly hard to place pixel-perfect !

Took me a couple tries to get Thailand, too, as it didn't snap to the map the first time I placed it.

A version with all countries would be an interesting teaching tool, to learn about geography and cartography. Would need to option to display only some countries at a time, to avoid overwhelming the user.

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