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Comment by sjwright | Hacker News Reader

When I saw the photos, I figured that the building's circumference would be so wide that curved glass would not just be unnecessary, but almost counter-productive, as it's difficult to curve glass without imperfections that might ruin its reflections.

Surely we'd be talking about small fractions of a degree per pane.

Can anyone estimate what the building circumference is, and therefore what amount of curve would be called for?

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Just looking at the proposed plans and comparing to Google Maps, I'd give a rough guestimate of 1100 ft for the building's diameter. So, that's about 3450 ft in circumference. That means a single degree of arc would cover about 960 ft. If each pane of glass were 10x48 and flat (as long as the building is tall), then they would form a 7200-sided polygon, and the angle between them would be 179.95 degrees, or a deflection of 0.05 degrees. So, while they claim a curved window, you wouldn't notice if it was flat. Unless, of course, my math is horribly misguided.

Edit: well somebody didn't like that. Anyway, I can't speak for the math, but my source for the diameter guestimate: The building site shown at [1], and the same site on Google maps [2]. Notice the scale in the bottom, showing 1000 ft. The building plan appears slightly larger than that, so that's where I got my estimate.

[1] http://www.youtube.com/watch?v=gtuz5OmOh_M&feature=playe...

[2] http://maps.google.ca/maps?f=q&source=s_q&hl=en&...

How do you get a 7200 sided polygon from a 3450 ft circumference? That would be 6 inch wide windows. Steve mentioned them having a process to create the largest pieces of glass in the world... which look to be on the order of 10+ ft wide. That would mean at most 360 panes of glass, each turning a full degree.

Maybe it's not easily perceptible, but how much do you wanna bet they mocked it up and Steve was like "Yeah, you can tell the difference. It just doesn't feel right."

See, I knew the math was wrong... thanks for pointing that out.

Based on the presentation and the handy ruler in Google maps, I'd estimate it to be about 400 meters in diameter. So around 1250 meters circumference. The curve is the same as the arc, so with 60 panes of glass about 21 meters long there's a six degree curve per pane.

Maybe all the rumors about curved glass weren't for the iPhone 5 but for the new building windows :)

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