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dan-robertsontoday at 1:23 PM1 replyview on HN

I’m not sure it’s very useful to rehash an argument with very tenuous relation to the OP here. The normal reason to use the Mercator projection in these situations is (a) it’s what people are used to and (b) it preserves angles so if you zoom in on a street then up will still be north and roads that are at right angles in the real world appear to be at right angles on the map. The latter property is pretty desirable and hard to achieve without doing some weird transition between projections as you zoom. This matters more for Europe (and I suppose parts of British Colombia) where there is a high population density at latitudes that are pretty extreme in much of the world.

I think Apple Maps has a pretty reasonable compromise here of transitioning from a globe to Mercator as you zoom, but this is a less nice UI with a mouse as you need to click to rotate the globe instead of pointing and zooming only. I don’t think there’s anything in this data that would make that unachievable – you just need to reproject the vector data a bit as you zoom out – but it takes some tricky mathematics to get right and so hasn’t been done yet.


Replies

willtemperleytoday at 3:14 PM

It's an important discussion because it's abundantly clear that almost nobody on this thread has a clue what they're talking about.

Web Mercator != Mercator.

I suggest most people on this thread need to go away ask the question "What's the difference between Web Mercator and Mercator".