[HN Gopher] What's the roundest country on earth? (2016)
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What's the roundest country on earth? (2016)
Author : acqbu
Score : 7 points
Date : 2022-02-18 20:48 UTC (2 hours ago)
(HTM) web link (citymonitor.ai)
(TXT) w3m dump (citymonitor.ai)
| ethbr0 wrote:
| Answer: Sierra Leone
|
| Surprised! Would have expected Vatican City. Which turns out to
| not actually be round at all (said as a prototypical
| geographically-ignorant American).
| jer0me wrote:
| https://youtu.be/jFg1SvLVlII
| dhosek wrote:
| Not sure I like the method for computing roundness. My
| instinctual approach would be to look at the value 4p _A_ / _P_ 2
| which has a circle=1 and the smaller values indicating less
| roundness (a square would be [?]0.79, a triangle [?]0.6)
|
| A pentagram would have 0.26.
| AlliedEnvy wrote:
| I had a similar objection and idea for alternative metric (with
| area and perimeter). But for most countries, the perimeter is
| ill-defined. See:
| https://en.wikipedia.org/wiki/Coastline_paradox
| dhosek wrote:
| The dataset's coordinates for the country boundaries are
| adequate for defining the coastlines.
| dhosek wrote:
| And as I think about it, this would make Island archipelagos
| maybe not show up as such extremes since we're ignoring the
| separations between the islands.
| nwallin wrote:
| > In short: the equirectangular projection distorts things,
| making countries closer to the poles look bigger while countries
| closer to the equator look smaller; the azimuthal projection
| accounts for this.
|
| This isn't quite right. Equirectangular projections stretches
| things _sideways_ near the poles. So a country that 's very
| circular that is near the poles will be a wide flat oval in in
| the projection. Consider a circular tarp that's dropped just a
| few feet from the South pole. It will stretch just thousands of a
| degree of latitude, but will stretch a hundred or more degrees of
| longitude.
|
| This is actually something that the much-maligned Mercator
| projection is actually good at. A circle on the globe will be a
| circle on the map. A circle near the poles will be a much, much
| bigger circle than a circle near the equator, but since you're
| talking about the ratios, to a significant extent the differences
| will cancel out.
|
| The azimuthal projection is not a global projection. Unlike
| Mercator, you can't just slap the whole world into an azimuthal
| projection and expect to get a globally useful map. You're not
| going to hang a map of the entire world in an azimuthal
| projection in a classroom, for instance. But for a local areas,
| say, just one single country, an azimuthal projection will be
| direction preserving from the central point, which is a useful
| property. So what the paper does, is if you have 200 countries or
| whatever, it defines 200 different azimuthal projections that are
| only useful in and around each country. And it uses each
| country's own projection to calculate how circular it is.
|
| The author declined to mention specifically which azimuthal
| projection they're using, which is unfortunate. Azimuthal means
| that direction from a central point are preserved. If this
| azimuthal projection is also equidistant, meaning equal distances
| from the central point are equal in the projection, then they're
| golden.
| senkora wrote:
| And of course Jay Foreman's (musical) video on the squarest
| country is well worth a watch!
|
| https://youtu.be/8mrNEVUuZdk
| kmm wrote:
| The original page linked in article seems more appropriate than
| the link itself: https://gciruelos.com/what-is-the-roundest-
| country.html
|
| Something is off with his dataset though, while 17, Monaco, looks
| quite round-ish in the image on the site, Monaco is actually
| among the more elongated and rectangular of the countries.
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(page generated 2022-02-18 23:02 UTC)