2807: Bad Map Projection: ABS(Longitude)

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Bad Map Projection: ABS(Longitude)

Title text: Positive vibes/longitudes only

Explanation

This explanation may be incomplete or incorrect: Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

In this map, Randall has plotted the world map featuring all the landmasses from both western and eastern hemispheres. But the longitudes west of the prime meridian, normally given negative values from 0° to -180°, have been made positive using the "ABS()" function that gives the absolute value by effectively stripping off the minus sign from any value. This results in the features on one side of the world being overlaid upon those of the other side, but reversed.

Thanks to the relative sparsity of western continents (most prominently the Americas, but also roughly half of Antarctica, the westernmost parts of Europe and Africa, the easternmost part of Siberia, and multiple Pacific islands), and the landless expanses of the Pacific, this is surprisingly not too dissimilar to an east-only fragment of a world map. Just with the reversed 'new world' lands added to the usual extents of continents of Africa and Eurasia and the somewhat familiar notable Antarctic Peninsula being recognisable but in an odd position (and reversed) with no sign of the Ross and Weddel Seas (as eastern-Antarctic landmass takes precedence). Most continents can be traced out, but North America overlaps so much with Asia that most of its outlines are hidden.

Some features of the real world disappear, such as the English Channel, the North American Great Lakes, and the Strait of Gibraltar. The Arabian Sea becomes a lake as South America cuts it off from the rest of the Indian Ocean (Indian-Pacific Ocean?).

To further interest the map-connoisseur, various locations are marked and dotted upon their genuine or reflected positions. Putting into close proximity various locations that have (mainly) trans-Atlantic separation in reality. Some of these locations have been renamed in this projection by combining the names of newly overlapping locations. These are:

• The "Palk-Panama Canal", combining the Palk Strait between India and Sri Lanka with the Panama Canal in Central America.
• The "Congo-Amazon Rainforest", combining the world's two largest tropical rainforests, the Congo in Africa and the Amazon in South America.
• The "Hudson Plain", combining Hudson Bay in North America with the West Siberian Plain.
• The "Kara-Baffin Sea", combining the Kara Sea to the north of Russia with Baffin Bay between Canada and Greenland.

Additionally in northern Siberia is the label "Franklin's Very Lost Expedition". Franklin's lost expedition was an attempt to find a passage from the Atlantic to the Pacific through the Arctic passage. Naturally a sea voyage ending up in the middle of a large landmass would be considered very lost.^{[citation needed]}

The map has a few spelling errors, such as Reykjavík being misspelled as Reykjavic, and the Aleutian islands being misspelled as the Aelutian islands.

Correct formula

A correct formula to get only positive longitudes (0-360°) is:

LONGITUDE=LONGITUDE+360*FLOOR(1-LONGITUDE/360)

This creates a Pacific centered world map.

Transcript

This transcript is incomplete. Please help editing it! Thanks.

[There is a map of the world with positive longitudes and negative longitudes overlapping. Caption above the map:]

Bad Map Projection #152:

Longitude=ABS(Longitude)

Whoops, made all longitudes positive

[The land masses are represented in white, and the oceans in light grey. Some capital cities, countries and geographical features are labeled.]

[Near Siberia is indicated:]

Franklin's very lost expedition

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Discussion

...actually, there's quite a bit of 'foldover' that's covered by the Atlantic, but it's still not quite so much as the Pacific gap across the ±180° edge-to-edge, so forgive me if consider the likes of places in India partnered with the over-adopted American locations as being trans-Atlantic (and across the whole width of Africa and some of the Indian Ocean too) rather than anything else. It could definitely do with a more precise analysis/description, though. Plus how bits of western Western Europe are folded over onto more-central Western Europe (not a very good mirror of Scotland, I think, but I'm particularly more familiar with its effective profile than Randall has any reason to be). 172.71.242.195 01:20, 27 July 2023 (UTC) This would make a great EU4 mod 172.68.146.52 01:21, 27 July 2023 (UTC)

Oh, good, thank you. I on ABS I couldn't get past antilock brakes. And the picture spam from the other day seemed to be tendeon repair. Looked like a surgicical procedure to to fasten cut tendons back together but I didn't see a cast to prevent movement. Shrug. Quite gross, as all surguries are. Poorly of course couldnt see all of the pic.172.71.222.70 02:35, 27 July 2023 (UTC)172.71.222.71 02:57, 27 July 2023 (UTC)

Added a very basic transcript because this comic is a little too complicated for me and it's my first time. Also, we need more positive vibes considering the previous comic about anti-vaxxers and the... interesting comments in the discussions.

Also, the Galapagos being near to Singapore (that's where I live) would be interesting! R3TRI8UTI0N (talk) 03:48, 27 July 2023 (UTC)

This map does not appear to be particularly…correct. For instance, Seoul, South Korea, is given as about 38N/155. But actually it is at 127E longitude. That's nowhere close. On a real map, 155E longitude is several hundred miles east of Japan into the open Pacific ocean, approx. the longitude of the Marshall Islands (but far north of them). Closer to home, for Randall and for me, Boston is given as about 59, but it is really 71W. What's up with that? Is everything shifted…and why? JohnHawkinson (talk) 05:00, 27 July 2023 (UTC)

Oh, wait. I was reading the coordinates like it was a cartesian plane, like on a Lambert or Mercator projection. But in retrospect this is some kind of elliptical projection (Robinson? Winkel tripel?) such that the longitude lines are bowed out, further as you get away from the center (here 90°, I guess). That is...too hard for me to read with precision without doing too much math and drawing lines (so I guess I'm lazy), so, probably it's just fine? I dunno. JohnHawkinson (talk) 05:09, 27 July 2023 (UTC)

This projection keeps the lines of latitude horizontal, allowing the lines of longitude to "bend", with only 90 degrees being vertical. 90 degrees, east/west, it doesn't really matter for this projection. Nutster (talk) 14:12, 27 July 2023 (UTC)

I just quickly put together an abs(longitude) "projection" image based on a real (public domain) map, to show what this would look like more realistically, with overlap. Are home-made images allowed? I cannot upload though ("You do not have permission to create new pages"). Is this because I'm a new user or are uploads prohibited for most users? Mtcv (talk) 07:41, 27 July 2023 (UTC)

It's just your newness (but I'm not sure how un-new/whatever you need to be). But I've 'sent in' things, before, by using some other public image host (not actually being new, but never having had the account here so of course the site won't accept my IP source - for good reason) and allowing an established uploader to spot the link, grab it and submit it locally by proxy if they thought it worthwhile.

I'm already half tempted to do an ABS(Latitude) for my own ennoyment. Maybe even combined with the above (might be too busy, though, as I mentally model how the Eurasiamerindiafricaustralian subercontinent wouldn't leave much room for recognisable land-mass coastline). Further arbitrary overlapping transforms could also be fun, and perhaps even 'wrong but rational-looking'. 172.70.90.165 08:16, 27 July 2023 (UTC)

I see, thanks for the info! Well here's a link: [1]. It's not that interesting, but to me it clarifies where North America has gone, all swallowed up by Asia. Better versions than this are certainly possible. I can add the image's info if someone uploads it. Absolute latitude sounds interesting too. Mtcv (talk) 08:44, 27 July 2023 (UTC)

All technical analysis aside, this map is really cool and would make a fantastic fantasy setting.

So... Lemuria was South America all along! Shirluban 12:20, 27 July 2023 (UTC)

• There's a misspelling on the map: "Aleutian" is misspelled as "Aelutian". --172.70.127.80 15:02, 27 July 2023 (UTC)
• Reykjavík is misspelled as Reykjavic. Makes it kinda Serbo-Croatic-looking. --Coconut Galaxy (talk) 16:47, 27 July 2023 (UTC)

Gondwanaland explained as a coordinate error. ProphetZarquon (talk) 15:06, 27 July 2023 (UTC)

The formula added in the "Correct formula" section of the explanation is not consistent with how Randall has overlaid the negative longitudes on top of the positive longitudes. This section was added by an anonymous editor. This formula mirrors the negative longitudes into positive longitudes but leaves them in a separate hemisphere from the positive longitudes, without overlaying the two hemispheres as Randall has done. I think this section needs to be removed completely. Anyone else agree? Ianrbibtitlht (talk) 19:29, 28 July 2023 (UTC)

I edited it. Not the author, but I think the intent was that this is what correct formula should have been used, instead of the "whoops!" indident where he actually used abs().

So I made it more clear (or, possibly less, you decide), plus added another alternative positive-normalising form of formula.

Though the use of mod (or % operator) may depend upon the mod-function implementation involved (whether it even needs the +360, can handle float longitudes, can perhaps even work well beyond -180..+180 input...) but it *can* be the much clearer method. Just test it with various values from all quadrants (and beyond +-180) ahead of time to make sure (what the comic map's creator should have done with their method).

Or, in code, just run something like while (lon<0) {lon+=360}; while (lon>=360) {lon-=360};, or however that'd work in your chosen coding dialect's syntax. And you might need to accept a possible bit of loop-spam if the input is somehow vastly high/low, but it works well in skipping over entirely unnecessary multiplative/divisive operations (it'll do no more than one of the loops, on the way past).

TMTOWTDI, though, and the usable methods are practically unlimited, I'd probably use whatever method looks good against the surrounding code (or shuttle it away into a subprocedure call, where I now make it look neat alongside its fellow subs).

Anyway, I think that section isn't necessary, but it may be of interest. 162.158.74.63 21:25, 28 July 2023 (UTC)

I wondered why it got so frigid and hard-to-breath overnight. Thanks a lot, Randal, for moving me to the Himalayas.These Are Not The Comments You Are Looking For (talk) 02:23, 1 August 2023 (UTC)

an ABS(Latitude) map

After looking at this map, I wanted to see, what an ABS(Latitude) map would look like and this is what I quickly threw together.

Unsurprisingly it doesn't change the world as much, since most of the land mass is on the northern hemisphere. The former South America has now created the worlds largest inland lake in the form of the Caribbean Sea and the Gulf of Mexico but the Panama Canal is still intact. Africa mostly folds up on itself and Australia is now the land bridge between China and Japan. However it was a fun and quick thing to do and I thought I should share it here.

Can you do abs(log), abs(lat)? 162.158.110.142 14:22, 27 July 2023 (UTC)

This would actually make a great fantasy map, as my father pointed out. Just swap out the city names with fantasy ones, and players would not be able to figure out where you got the map from. 172.70.114.141 14:41, 27 July 2023 (UTC)

Even at first glance it looks faked up though, because half the paisleys are backward.

ProphetZarquon (talk) 15:06, 27 July 2023 (UTC)

I'm in Serbia and nothing changes for me. I wonder how the Indian subcontinent and Central Asia are dealing with the sudden Americans. Andrewtheexplainer (talk) 15:27, 28 July 2023 (UTC)

As a Canadian of course I would notice this. It appears Canada has the most references on the map with seven just ahead of the USA with only six. Given our typical low self esteem, we take our "wins" whenever we can: thanks Randall MDwayne.ca (talk) 20:27, 5 August 2023 (UTC)