1784: "Bad Map Projection: Liquid Resize"

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Copper Bezel » Thu Jan 12, 2017 1:49 am UTC

hotaru wrote:when starting from a projection that isn't complete shit.
20.deg.borders-p7p4-lg-lqr.jpg

Uh-oh.

Think about the path you set us on, hotaru. Ten pages from now, when Steven Waterman awakes, you will remember your choice at this moment.
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Pfhorrest » Thu Jan 12, 2017 1:50 am UTC

If you did this on a topographical map, would it show all of the world's contours as having the same slope? (Because the distances between the elevation lines would get collapsed). So you'd basically have mountain ranged dropping straight down to seashores and all the flat plains of the world condensed?

Think about the path you set us on, hotaru. Ten pages from now, when Steven Waterman awakes, you will remember your choice at this moment.

Hey I kinda miss Steve. It was nice all being united in a common cause, instead of worrying which one of you is going to unexpectedly piss me off next...
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby sotanaht » Thu Jan 12, 2017 1:54 am UTC

So what projection did he start with? Photoshop is 2d, so whatever map he started with to be resized would also have to be 2d, and hence a projection of some kind.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby jc » Thu Jan 12, 2017 3:31 am UTC

Pfhorrest wrote:well, it's better than Mercator

Better at what?

We all love to mock the Mercator projection, of course, but fact is that it had a very practical use in the days before computerized navigation systems. A straight line on the map was based on "lines of constant course", which was a good tool for sailors using the navigation techniques of the time. Yes, the distances were garbage, but distance didn't correlate well with time back then. If your ships are powered by the wind, your speed is dependent on the wind, and thus essentially unpredictable and irreproducible. But they had functioning compasses, and could somewhat reliably follow a line on a Mercator map, giving them a good chance of reaching land very close to their intended destination.

It's well understood that all projections of a sphere onto a 2d surface is invariable "wrong" in many respects. A projection is only "good" if it does something useful that you want it to do. A "good" projection is routinely "bad" for people using the map for a different purpose.

My reaction to this comic was that I didn't see any real reason to call it a bad projection. It looks quite useful to me, for purposes that many people might agree with. OTOH, if I were a whale or albatross or giant squid, I'd probably find it a horrible projection, since it eliminates almost all of the world where I and my people live. But this doesn't really make it a "bad projection", since all projections are "bad" in the same sense; they don't work for the purposes of some people (or species).

I do sorta like the example based on resizing the dymaxion projection. But our whale, albatross and giant squid would also object to it, since it destroys their habitat in the opposite way of the comic, by splitting it up into a lot of disconnected chunks scattered around the edges of the continents. I wonder that would be a good projection for them ...

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby BytEfLUSh » Thu Jan 12, 2017 4:13 am UTC

Image
What is that thing, and why is it enclosed in a #424242 line?

(sorry, I just had to...)

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Pfhorrest » Thu Jan 12, 2017 4:22 am UTC

jc wrote:
Pfhorrest wrote:well, it's better than Mercator

Better at what?


ahammel wrote:inb4 "well, it's better than Mercator"


BytEfLUSh wrote:What is that thing

Everybody knows a little place called Kosovo.
Last edited by Pfhorrest on Thu Jan 12, 2017 4:26 am UTC, edited 2 times in total.
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Copper Bezel » Thu Jan 12, 2017 4:23 am UTC

BytEfLUSh wrote:What is that thing, and why is it enclosed in a #424242 line?

(sorry, I just had to...)

No, please, fighting over Kosovo's status as an independent nation is bound to be tamer than the fight over map projections.
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby BytEfLUSh » Thu Jan 12, 2017 4:29 am UTC

Copper Bezel wrote:
BytEfLUSh wrote:What is that thing, and why is it enclosed in a #424242 line?

(sorry, I just had to...)

No, please, fighting over Kosovo's status as an independent nation is bound to be tamer than the fight over map projections.

Ahhh, I guess you're right. I like this projection very much, though. It's the best one, and all the others should be replaced by this.

Am I getting better at this?

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby LockeZ » Thu Jan 12, 2017 9:35 am UTC

No one could fight about Kosovo. Just thinking about it makes you start singing relaxing songs. Ooh I want to take you down to Kosovo, we'll get there fast and then we'll take it slow. That's where we want to go, way down in Kosovo. (Bermuda, Bahama, come on pretty mama)

@jc, I'm curious what use you're imagining for the liquid resize map.

Also, more importantly, I'm wondering if we could take an arbitrary map projection, do the liquid resize to it, and then reverse the projection algorithm to print it back onto a globe.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Soupspoon » Thu Jan 12, 2017 11:57 am UTC

LockeZ wrote:Also, more importantly, I'm wondering if we could take an arbitrary map projection, do the liquid resize to it, and then reverse the projection algorithm to print it back onto a globe.

You could, but you might be better to go for a specifically-spherical Liquid Resize that identifes circumglobal lines of least detail1. And then shuffling (necessarily in the form of vector data, not raster, at least as a guide to morphing vectors you'd later use to shuffle and combine/multiply original projection pixels onto their newly shuffled printed locations?) detail around an effectively fixed-size globe, albeit reducing the spherical resolution...

Umm, description got nestedly complicated, even after attempts to breakout with feetnete. What I mean to say is that a sphere is (assuming no distortion of space itself) going to have a constant solid angle (4pi steradian) that can be covered by less pixels (if now primarily of the more significant type) only by increasing the coverage of each of those pixels, and because there have already had to been compromises in the pixel-to-surface-area relationships, areas of extreme distortion (sphere-to-plane, then back again after a planar liquid removal has likely altered the distortion-position) cause algorithm bias.

Thus perhaps best to treat as vectorised data, locally analysing areas (I suggest a gnomonic zoom, but then I would) for detail-density that allows barren zones (in circumglobal rings, ideally) to be deflated by moving complicated ones over them (extending in from the relative 'poles' to the 'equatorial' ring concerned) until some arbitrary new density is reached. As it's not so much an (old-width-in-pixels) to (new-width-in-pixels) situation.

Alternately, deal with pixels arrayed, not strictly grid-like, but as per triangles on two geodesic domes of two different degrees of complexity. And/or the dimples on a golf-ball, likely very similar (I see that there are commonly a range of 300 to 450 on commonly produced balls). Either way a high-enough density to dilute the strange (pentagonally-based) zones in both before and after the removal of rings of triangles that lead through acceptable intermediate forms.


(Darn, still going complex. It's not like I don't think that my fellow xkcdites can deal with it, but it's in my mind as being far more straightforward and simple, just coming out through the keyboard with too many side-comments. Sorry. Hopefully YGTI.)



1 Orietated in any direction2 perhaps meandering lines no shorter than a great circle and yet balanced around the 'mean great circle' to discourage circumpolar or 'just cut around Australia'. At least until the algorithm can't find a better mid-Atlantic-ridge/Arctic/mid-Pacific/across-Antarctica line or a Panama/Atlantic/Mediteranean/Suez/Indian/South-China/Pacific one, to name just two visually-obvious (probably not necessarily computational prominent) examples.
2 Not just North/South and East/West, and straight projection-edge lines of either type would probably be disqualified by the weighting towards real great-circle slices, above.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Sableagle » Thu Jan 12, 2017 4:59 pm UTC

Soupspoon wrote:BTW: Earth is already continuing to reshape and shuffle its landmasses, as we all know, but this one will be interesting to watch, if anyone gets a chance...
Smaller scale, shorter time-scale, closer to me, another bit of surface redesign may be coming soon.


BytEfLUSh wrote:What is that thing, and why is it enclosed in a #424242 line?
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby chrisjwmartin » Fri Jan 13, 2017 10:54 am UTC

Mercator is pretty much the best map projection there is, if what you want from a map projection is to be able to navigate ships across large distances.

There is no such thing as "bad" map projections, only map projections that are better or worse suited to particular purposes.

Anyway, what is everyone's favourite map projection? Mine is the Peirce quincuncial. It is so beautiful, and it tessellates.

Image

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby somitomi » Fri Jan 13, 2017 11:17 am UTC

When it comes to world maps, I like circular or elliptical ones better. Mostly for aesthetic reasons, corners just seem like a weird idea on the map of a mostly spherical object. I don't actually use world maps for anything, so looking nice is the only reason for me to even have one. Mollweide is nice for example:
Mollweide.png
Mollweide.png (90.22 KiB) Viewed 3883 times

I also like orthographic maps, because they're pretty close to what you'd see from really far away:
Orthographic.png
Orthographic.png (139.71 KiB) Viewed 3883 times
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby orthogon » Fri Jan 13, 2017 4:07 pm UTC

chrisjwmartin wrote:Mercator is pretty much the best map projection there is, if what you want from a map projection is to be able to navigate ships across large distances.

There is no such thing as "bad" map projections, only map projections that are better or worse suited to particular purposes.

That's sort of true, but as I understand it the Mercator isn't really suited to any purpose in the modern world, because if you want to navigate ships across large distances you shouldn't do it by sailing at a constant bearing taken off a Mercator. Unless you're near to the equator your route will end up being inefficient, since most great circles are nothing like straight lines (and vice versa). I'm talking about maps of significant portions of the surface here; slices of transverse Mercator used locally are another story. Come to think of it, you're unlikely to be navigating using a map of the whole world anyway, and as I understand it the "Mercator is bad" thing is all about world maps.

chrisjwmartin wrote:Anyway, what is everyone's favourite map projection? Mine is the Peirce quincuncial. It is so beautiful, and it tessellates.

You do realise what that says about you, I take it?
xtifr wrote:... and orthogon merely sounds undecided.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby somitomi » Fri Jan 13, 2017 4:50 pm UTC

orthogon wrote:You do realise what that says about you, I take it?

I haven't a clue. Although I do like globes...
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby chrisjwmartin » Fri Jan 13, 2017 7:38 pm UTC

orthogon wrote:
chrisjwmartin wrote:Anyway, what is everyone's favourite map projection? Mine is the Peirce quincuncial. It is so beautiful, and it tessellates.

You do realise what that says about you, I take it?

I do! That is my second-favourite xkcd comic. I laughed so hard when it first came out, because it summed me up perfectly. My point above about "no bad projections" is basically saying that what we see in maps is ourselves and our human purposes. I really did sit silently in the cinema for about twenty minutes after watching Inception - my friends waiting outside all laughed at me when I eventually emerged. I am often freaked out when I think about how everyone has so much poo and blood inside them (skeletons not so much, but same principle). I have really looked at my hands.

I even showed my new girlfriend, who had no idea why I was laughing so much at some weird black-and-white hand-drawn maps. Can't have been that much of an error though as she is now my wife.

somitomi, you seem like you would like the Van Der Grinten. After all, the earth's not a square – it's a circle.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby McHell » Mon Jan 16, 2017 11:26 am UTC

LockeZ wrote:No one could fight about Kosovo. Just thinking about it makes you start singing relaxing songs.

The Serbs and Kosovars disagree on this. That nineties shitstorm isn't completely over.

Actually, that was Saturday; yesterday Serbia has reformulated it as a military threat towards Kosovo.

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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Pfhorrest » Mon Jan 16, 2017 9:03 pm UTC

The joke.

(Everybody knows a little place called Kosovo...)
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Re: 1784: "Bad Map Projection: Liquid Resize"

Postby Steve the Pocket » Wed Jan 18, 2017 7:39 am UTC

i never could remember the capital of Bolegdeh...
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