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I'm trying to curve the lines between points on a RaphaelJS map like Tata Communications - but how did they do it? What sort of mathematics lie behind these curves - unless ofcourse they're all manually drawn?

Some dude told me Catmull-Rom Splines, but those will only smoothen lines, not curve them.

Many thanks!

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Have you zoomed into that map to see details? Look at Miami and the Bahamas for instance: it is clear that even the endpoints of the curves are manually placed and edited. – whuber Jun 5 '12 at 13:15
Might tmcw's solution about using arc.js at least get me close though? – Mark Boulder Jun 5 '12 at 16:36
Not even remotely: it's for computing geodetically straight lines, not curves. Merely as an example of the myriad approaches to this, see… – whuber Jun 5 '12 at 16:41
Wicked! Thanks a lot whuber! – Mark Boulder Jun 5 '12 at 16:50

See arc.js for a semi-automated solution.

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