explain xkcd - User contributions [en]

1784: Bad Map Projection: Liquid Resize

2020-01-17T23:37:57Z

Mattmatician: /* Explanation */

{{comic
| number = 1784
| date = January 11, 2017
| title = Bad Map Projection: Liquid Resize
| image = bad_map_projection_liquid_resize.png
| titletext = This map preserves the shapes of Tissot's indicatrices pretty well, as long as you draw them in before running the resize.
}}

==Explanation==
This is the first comic in the series of [[:Category:Bad Map Projections|Bad Map Projections]] that continues in [[1799: Bad Map Projection: Time Zones]], released just a bit more than a month after this one, and [[2256: Bad Map Projection: South America]], released 3 years later

There is no perfect way to draw a map of the world on a flat piece of paper. Each one will introduce a different type of distortion, and the best projection for a given situation is sometimes disputed. [[Randall]] previously explored 12 different projections in [[977: Map Projections]], and expressed his disdain for some types he sees as less efficient but whose users feel superior. None of them are truly perfect as any 2D map projection will always distort in a way the spherical reality, and a map projection that is useful for one aspect (like navigation, geographical shapes and masses visualization, etc.) will not be so for all the others. Local maps of smaller areas can be quite accurate, but the idea of both these map projection comics is to map the entire globe on a flat surface.

This comic suggests that there are many other projections than the 12 from the previous map projection comic, and Randall seems to have an entire list, of which at least 107 are "Bad Map Projections." The one presented here is #107 and is it called the "Liquid Resize." It is unclear if he includes the previous 12 in this list. Quite possibly he does, since all 2D projections of the surface of a 3D sphere will be bad in certain respects. (The next comic's projections ''Time Zones'' based on these, has #79 and could be concluded as being less bad than this one, which also seems realistic as this map looks more like a normal map projections, although it also has huge flaws).

The ''Liquid Resize'' map projection, however, is not only useless for most map applications -- as the size, shape, and position of most countries are quite distorted -- but its creation includes two steps which are outright counterproductive. If the list is sorted from best to worst it may be hard to find a worse projection method than this, so finding 106 projections better than this one seems realistic!

First, this method needs a planar map projection as its starting point, thus compounding the problems right off the bat. Planar projections are relatively accurate near the center but heavily distorted toward the edges. A famous example of a planar projection is the logo of the {{w|United Nations}}. Planar projections are just about useful for 3D graphics rendering, if the user needs a quick, inexpensive way to store map textures that will later be attached to a sphere.

Second, the map uses [https://helpx.adobe.com/photoshop/using/content-aware-scaling.html Photoshop's content aware resizing tool], a very questionable choice. (Using a Photoshop tool for a task it is not intended for was also used in [[1685: Patch]] where a GNU patch tool was replaced with Adobe Photoshop's patch tool to compile code.) The content aware resizing tool resizes images by identifying what it thinks are important details and preserving these, while shrinking or stretching less detailed areas. For example, [http://knowyourmeme.com/photos/710073-content-aware-scaling when used on a face], the algorithm detects that the eyes and mouth are important details and tries to keep these in place, while stretching the skin around it. When applied to a map, this means that areas with lots of countries - and therefore lots of detail - such as Europe, West Africa, the Eastern Mediterranean and Central America/the Caribbean are relatively unchanged, while big countries like India, China and the US are very warped. The choices that the resizing tool makes are also dependent on the exact visual features of the original map, such as the choice of not having any topography or infrastructure drawn on, or not including a latitude/longitude grid, so what areas are deemed as unimportant is even more arbitrary than it would be on, say, a photographic picture of the Earth.

[http://knowyourmeme.com/memes/content-aware-scaling Bad content aware scaling] is already a meme. This projection does do a good job, however, of making almost every country clearly visible and indicating which countries are neighbors.
South America fits into Africa almost as it did in the era of the super-continent {{w|Pangaea}}.

{{w|Tissot's indicatrices}} are equally sized small circles overlaid on a globe to show the distortion of a particular map projection; if the map distortion distorts the shapes or areas of countries, it will do the same to the circles. The title text suggests that the shapes of Tissot's indicatrices would be pretty well preserved by the Liquid Resize transformation, 'as long as you draw them in before running the resize'. This is a joke. "Drawing them in before running the resize" means that a different projection would be generated (probably preserving the indicatrices themselves), making the use of the indicatrices meaningless, sort of like cheating. In fact by drawing them small enough there will be no resizing at all.

The making of this comic may have caused Randall's comic the week after about Dvorak - see the [[1787: Voice Commands#Trivia|trivia]] for [[1787: Voice Commands]].

==Transcript==
:[Caption at the top of the panel:]
:Bad map projection #107:
:<big>The Liquid Resize</big>
:A political map compressed using Photoshop's content-aware resizing algorithm to cut down on unused blank space

:[Below the caption there is a map of the world divided and colored by political boundaries, with outlines around each continent in black and around each country in dark gray. Antarctica is colored in light gray, bodies of water in white, and countries in pale shades of red, orange, yellow, green, blue, and purple. The map is heavily distorted, with Africa in the center and the other continents curving around it, approximating the bounds of a square with rounded corners. The oceans have been removed but also huge countries like the US, Australia, Brazil, Russia and especially India and Argentina have been heavily distorted while areas in the center with many smaller countries like Africa and Europe is almost unchanged.]

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Maps]]
[[Category:Bad Map Projections]]

2252: Parenthetical Names

2020-01-08T22:03:30Z

Mattmatician:

{{comic
| number = 2252
| date = January 8, 2020
| title = Parenthetical Names
| image = parenthetical_names.png
| titletext = I never got around to seeing that movie about the battle (of Midway).
}}

==Explanation==
{{incomplete|Created by a PARENTHESIS. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

The use of parentheses is commonly used on {{w|Wikipedia}} to distinguish between different articles where the subject has the same name. Typing "Stealth", for example, would lead to suggestions such as {{w|Stealth (film)}}, {{w|Stealth (video game)}}, and {{w|Stealth (roller coaster)}}.

''{{w|Sonic the Hedgehog (film)|Sonic the Hedgehog}}'' in a movie scheduled for release in February 2020. The film stars an anthropomorphic hedgehog named {{w|Sonic the Hedgehog (character)|Sonic}}. When the first trailer was released, the public reacted with shock and horror at the movie's design of Sonic, who was said to fall into the "{{w|uncanny valley}}" by being too anthropomorphic and not cartoony enough. The design was hastily re-developed, which was received much more favorably; evidently, Cueball has warmed to the movie and is asking his friends if they want to go see it.

The title-text alters the pattern slightly by discussing the {{w|battle of Midway}} (i.e. the X '''of''' Y).

Part of the humor in this comic is imagining that Cueball's (or Randall's) social circle have lots of discussions about things named Sonic, Jack, Popeye, and a battle, which are nevertheless not the Hedgehog, the Ripper, the Sailor Man, or Midway, respectively.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

[Cueball stands, holding his phone. Text message boxes are above him.]

Do you want to go see Sonic (the Hedgehog)?

Why are there so many books about Jack (the Ripper)?

I didn't know Robin Williams once played Popeye (the Sailor Man)

[Caption below the panel:]

My Hobby:

Whenever I mention anyone called "<Name> the <X>," I like to put "the <X>" in parentheses, like I added it as a clarification
{{comic discussion}}

2252: Parenthetical Names

2020-01-08T22:02:24Z

Mattmatician:

{{comic
| number = 2252
| date = January 8, 2020
| title = Parenthetical Names
| image = parenthetical_names.png
| titletext = I never got around to seeing that movie about the battle (of Midway).
}}

==Explanation==
{{incomplete|Created by a BOT (explainxkcd's). Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

The use of parentheses is commonly used on {{w|Wikipedia}} to distinguish between different articles where the subject has the same name. Typing "Stealth", for example, would lead to suggestions such as {{w|Stealth (film)}}, {{w|Stealth (video game)}}, and {{w|Stealth (roller coaster)}}.

''{{w|Sonic the Hedgehog (film)|Sonic the Hedgehog}}'' in a movie scheduled for release in February 2020. The film stars an anthropomorphic hedgehog named {{w|Sonic the Hedgehog (character)|Sonic}}.

The title-text alters the pattern slightly by discussing the {{w|battle of Midway}} (i.e. the X '''of''' Y).

Part of the humor in this comic is imagining that Cueball's (or Randall's) social circle have lots of discussions about things named Sonic, Jack, Popeye, and a battle, which are nevertheless not the Hedgehog, the Ripper, the Sailor Man, or Midway, respectively.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

[Cueball stands, holding his phone. Text message boxes are above him.]

Do you want to go see Sonic (the Hedgehog)?

Why are there so many books about Jack (the Ripper)?

I didn't know Robin Williams once played Popeye (the Sailor Man)

[Caption below the panel:]

My Hobby:

Whenever I mention anyone called "<Name> the <X>," I like to put "the <X>" in parentheses, like I added it as a clarification
{{comic discussion}}

2252: Parenthetical Names

2020-01-08T22:01:37Z

Mattmatician:

{{comic
| number = 2252
| date = January 8, 2020
| title = Parenthetical Names
| image = parenthetical_names.png
| titletext = I never got around to seeing that movie about the battle (of Midway).
}}

==Explanation==
{{incomplete|Created by a BOT (explainxkcd's). Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

The use of parentheses is commonly used on {{w|Wikipedia}} to distinguish between different articles where the subject has the same name. Typing "Stealth", for example, would lead to suggestions such as {{w|Stealth (film)}}, {{w|Stealth (video game)}}, and {{w|Stealth (roller coaster)}}.

''{{w|Sonic the Hedgehog (film)|Sonic the Hedgehog}}'' in a movie scheduled for release in February 2020. The film stars an anthropomorphic hedgehog named {{w|Sonic the Hedgehog (character)|Sonic}}.

The title-text alters the pattern slightly by discussing the {{w|battle of Midway}} (i.e. the X '''of''' Y).

Part of the humor in this comic is imagining that Cueball's (or Randall's) social circle have lots of discussions about things named Sonic, Jack, Popeye, and a battle, which are nevertheless not the Hedgehog, the Ripper, the Sailor Man, or Midway, respectively.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

[Cueball stands, holding his phone. Text message boxes are above him.]

Do you want to go see Sonic (the Hedgehog)?

Why are there so many books about Jack (the Ripper)?

I didn't know Robin Williams once played Popeye (the Sailor Man)

[Caption below the panel:]
My Hobby:
Whenever I mention anyone called "<Name> the <X>," I like to put "the <X>" in parentheses, like I added it as a clarification
{{comic discussion}}