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exosyphen
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Postby exosyphen » Fri Jul 22, 2005 7:45 am

Would be great if earth would have been a perfect cube :)
Why is the earth a sphere? Let's see who knows the scientific explanation :)
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Postby Rkiver » Fri Jul 22, 2005 8:58 am

The Earth isn't a sphere. The earth is a slightly squished sphere, it is flatter at the poles. This is due to how the earth rotated as it cooled from molten this that and the other into the globe we know today.

You want the maths equations that go along with it?
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exosyphen
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Postby exosyphen » Fri Jul 22, 2005 9:12 am

Neah :) They nearly killed me in college over those equations :)
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Postby doormat » Fri Jul 22, 2005 6:12 pm

No one is the center of the map. The meridian is the center of the cartesian projection, though. It isn't accurate anywhere else. There are projections which don't have the meridian through london, but they arn't rectagular. Flattening a sphere onto a plane is realy complex math, and there arn't many ways to do it without destorting the edges. The advange of putting london in the middle: no land around the edges.

Having said that, putting america in the middle results in a more accurate shape for america.

We need pocket holograms, dammit!
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exosyphen
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Postby exosyphen » Fri Jul 22, 2005 7:02 pm

Indeed it's a pretty complex task to make a correct projection (I never believed 1+1 could equal to 1.41 until I did metrical spaces).

Actually computing distances and everything on a sphere takes a completely different math.

Indeed, holograms or 3D graphics can offer the best representation of the world map.

I still LOVE having my real earth globe that spins :) Gotta put it back on my desk :)
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Postby Deepsmeg » Fri Jul 22, 2005 7:40 pm

sqr(1) + sqr(1) = sqr(2)
therefore, 1 + 1 is 1.41

Is that the logic you're using?
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exosyphen
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Postby exosyphen » Fri Jul 22, 2005 7:50 pm

In 2D/3D "flat space", the distance between 2 points is defined as :

dist(x,y) = |x - y| - this would apply for our flat world.
But, there are space for which your formula above applies.

Think of the distance between 2 points on a sphere for example. It's NOT a straight line.
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Postby Mas Tnega » Fri Jul 22, 2005 8:21 pm

Deepsmeg wrote:sqr(1) + sqr(1) = sqr(2)
therefore, 1 + 1 is 1.41

Is that the logic you're using?
The same quality of mathematical logic that gives you (1 + i)^2 = 2.
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Postby Stewsburntmonkey » Fri Jul 22, 2005 11:38 pm

doormat wrote:No one is the center of the map. The meridian is the center of the cartesian projection, though. It isn't accurate anywhere else. There are projections which don't have the meridian through london, but they arn't rectagular. Flattening a sphere onto a plane is realy complex math, and there arn't many ways to do it without destorting the edges. The advange of putting london in the middle: no land around the edges.

Having said that, putting america in the middle results in a more accurate shape for america.

We need pocket holograms, dammit!


Actually a map (Mercator projection) horizontally centered on Greenwich still cuts off part of Asia, although it is a significantly smaller section than maps (again Mercator projections) horizontally centered on the US.

And a meridian is just a line connecting the north and south poles. There are meridians at every point on the earth (the poles being trivially unique). There is no real benefit to having the prime meridian run through the UK (actually there are better places to have it geographically). :)
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Postby Deepsmeg » Sat Jul 23, 2005 12:11 am

We came up with the idea of time zones and stuff, so we're keeping the meridian!
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Postby doormat » Sat Jul 23, 2005 12:14 pm

Actualy, mapping the earth is realy complicated. The admiralty maps are still the baseline, and they assume a meridian through london. So any other projection has to try and adapt them, and isn't as accurate. (And they almost always use projections that were developed for a london meridian: to do a new map realy needs a whole new projection, but that's pretty hard too.)

Orbital maps have a problem in that they don't plot clear lines: they can be affected by tides and shallow seas and what have you.

I don't know if you've heard this story, but there used to be a city-state in the middle of... I think it was the sahara, you'd have to look it up. Anyway, this city made it's wealth (and it was wealthy) by serving as a trade intersection: it had no natural resorces. One day, during the reign of Queen Victoria, the leader of this city insulted the British. The Queen demanded that the navy send a warship. The admiralty appoligised, but explained that the city was... erm... in the middle of dry land. So the Queen asked the admiralty to bring the map from the chart room. She cut the city out with her embroidery scissors and declared that it would never again appear on a british map.

That city isn't there any more. No one even knows what it was called. They found the ruins, and there is still a hole in the map, but that's it. Uncharted, it lost it's trade and faded away.

We take maps for granted, but the're actualy realy complicated and valuable things. I know I couldn't draw one: the maths is totaly beyond me. And holding the primary maps was a huge source of power in the days before easy printing, just as having the GPS system is today.
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Postby Stewsburntmonkey » Sat Jul 23, 2005 3:56 pm

doormat wrote:Actualy, mapping the earth is realy complicated. The admiralty maps are still the baseline, and they assume a meridian through london. So any other projection has to try and adapt them, and isn't as accurate. (And they almost always use projections that were developed for a london meridian: to do a new map realy needs a whole new projection, but that's pretty hard too.)


Actually with modern computers creating a new projection is rather easy (my uncle does it all the time), but whatever. . .
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Postby doormat » Sat Jul 23, 2005 6:34 pm

Yeah... piece of piss...

Honestly, stews. :roll:
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Postby Stewsburntmonkey » Sat Jul 23, 2005 6:50 pm

Umm. . . That is all rather simple math. . . Just because it may be over your head, doesn't make it difficult. And even complex projections are easily achieved with a computer.

That site does absolutely nothing to back up the junk you have been arguing.
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Postby exosyphen » Sat Jul 23, 2005 7:33 pm

Who put the brits on the middle of the map? :-/

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