1784: Bad Map Projection: Liquid Resize
|Bad Map Projection: Liquid Resize|
Title text: This map preserves the shapes of Tissot's indicatrices pretty well, as long as you draw them in before running the resize.
| This explanation may be incomplete or incorrect: Partial -- explains a few underlying concepts but needs a lead section.|
If you can address this issue, please edit the page! Thanks.
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 very disputed. Randall previously explored different projections in 977: Map Projections, and expressed his disdain for some types he sees as less efficient but whose users feel superior.
In this comic, he suggests (supposedly as part of a long list of other equally-terrible maps) a new map projection which is not only useless for most map applications -- as the size, shape, and position of most countries are quite distorted -- but whose creation includes two steps which are outright counterproductive.
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 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 Photoshop's content aware resizing tool, a very questionable choice. 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, 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.
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 neighbours. South America fits into Africa almost as it did in the era of the super-continent Pangaea.
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.
- [Caption at the top of the panel:]
- Bad map projection #107:
- The Liquid Resize
- 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.]
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