{"id":3282,"date":"2021-08-26T17:54:23","date_gmt":"2021-08-26T05:54:23","guid":{"rendered":"http:\/\/blogs.lincoln.ac.nz\/gis\/?p=3282"},"modified":"2023-05-07T02:54:34","modified_gmt":"2023-05-07T02:54:34","slug":"three-geographic-strikes","status":"publish","type":"post","link":"https:\/\/blogs.lincoln.ac.nz\/gis\/three-geographic-strikes\/","title":{"rendered":"Three Geographic Strikes"},"content":{"rendered":"

So one of my guilty pleasures is doing Stuff’s two daily trivia quizzes.\u00a0 That and crossword puzzles.\u00a0 And…well you probably don’t want to hear about the other ones…\u00a0 (Ed. Thanks<\/em>).\u00a0 Now Stuff has started up a new quiz called Three Strikes.\u00a0 In this one you get six or seven things that need to be arranged in some order and three tries to see if you can get it right.\u00a0 Yesterday they did the planets in order from the sun (nailed it). But today, well, here comes some geography<\/a>: arrange these countries from largest to smallest according to their geographic size:<\/p>\n

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Okay – so I can either go on gut feeling here and have a go or, can I use some maps to help?\u00a0 Let’s start here:<\/p>\n

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This is a\u00a0world map with the countries in question outlined in black.\u00a0(Ed: Oh, I see what’s going on here…this is just another excuse for you to talk about map projections, isn’t it.\u00a0 ISN’T IT!<\/em>)\u00a0 Going by this, I might form my preliminary guesses – I’ll clearly go with Russia first (it’s massive!), then Canada, the US (tough call there), China, Australia, Brazil (another tough call) and finally India.\u00a0 But wait, I’ve got to be a bit careful using this, as a closer look should draw my attention to the distortions in the map – one need only look at Antarctica to see that it might be overestimating its size and extent a wee bit.<\/p>\n

That’s down to the map projection<\/a>, Mercator in this case.\u00a0 It’s well known that Mercator projections distort the shape and size of land masses as you get closer to the poles.\u00a0 So Russia, Canada and the US appear larger than they actually are in a relative sense, but their shapes are roughly preserved.\u00a0 For the record, the map above uses the WGS 1984 Web Mercator (auxiliary sphere)<\/a> projection – it is a conformal projection meaning that it preserves direction (which makes Mercator great for navigation) and the shape of features but distorts distance and area.\u00a0 All map projections distort one or more of area, distance, angle or shape – which one we choose to use depends on what we’re willing to sacrifice.\u00a0 Can I do something to improve this map?<\/p>\n

Mais oui, cher lecteur!\u00a0 I could change the map projection to one that preserves relative area, such as the cylindrical equal area<\/a> projection.\u00a0 Here’s what that one looks like:<\/p>\n

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(The projection was changed by right-clicking the map name, going to Properties > Coordinate System and searching for “cylindrical equal area”)<\/em><\/p>\n

As we can see, in the process of preserving area we have sacrificed shape and I wouldn’t trust distance measurements unless I was maybe<\/em> making them east-west.\u00a0 But at least I’m a bit more confident that the relative areas are more correct.\u00a0 I’m pretty clear on my smallest country (India), still unclear between Brazil and Australia.\u00a0 Russia’s the largest and it’s a tight battle between Canada, the US and China.\u00a0 Any other projections to play with?<\/p>\n

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That’s a pretty wild one – it’s the Adams Square II<\/a> conformal (area preserving) projection.\u00a0 Going by this one, well Australia looks bigger than Brazil now, Russia still leads and I’m going to edge Canada out a bit over the US.\u00a0 But the more I do this, the more hopeless it feels – I’m not sure I’m ever going to get a clear answer so…<\/a> (some nice maps on that page, by the way.\u00a0 And please note that this is one of the few times I might say that a table of data is more effective than a map of those same data.)<\/p>\n

In the spirit of I don’t know what, I actually chose to not cheat, and guess what.\u00a0 I struck out.\u00a0 Three times.\u00a0 Didn’t even get close.\u00a0 But it was fun.\u00a0 Spoiler alert<\/strong>: here is the correct order:<\/p>\n

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And for the record <\/a>(all areas in km2<\/sup>):<\/p>\n