The Unicorn of Map Projections

It’s a shame that Sarah Battersby’s essay in The International Journal of Cartography, “The Unicorn of Map Projections,” is behind a paywall: it looks at the recent rash of map projections that purport to solve all our mapping problems.” There have been more than a few that have claimed the title of “most accurate map”; Battersby refers to these projections as a class as unicorns. The most recent example of this I dismissed as the cartographic equivalent of a spherical cow; five years ago there was also Narukawa’s AuthaGraph map; and of course there was the Peters map.

The Spherical Cow Projection

Today is The Map Room’s 18th anniversary. When I started this blog back in March 2003, it was as an exercise in self-education: I liked maps a lot, but knew very little about them, and thought that the blogging process would enable me to learn things and share what I learned with my readers. The idea that I’m some kind of map expert is just silly: I have no professional credentials whatsoever, not in cartography, not in geospatial, not even in illustration. (I haven’t even taken geography since high school.)

But that’s not to say that I haven’t picked up some knowledge: I’ve turned my longstanding interest in fantasy maps into a few published articles (with more still in the works or in press), so I will concede the point on that front. But in general what I do have is exposure. Over the past 18 years I have seen just about everything to do with maps, and so I know a little bit about just about everything. Not enough to be employed at any map-related job, but 18 years of paying attention, of synthesizing everything I’ve seen and read, has afforded me some perspective.

Enough to call out obvious horseshit when I see it.

Continue reading “The Spherical Cow Projection”

Map Projections for Babies

Map Projections for BabiesLate last year Dan Ford launched a Kickstarter to create a board book (i.e., a children’s book printed on paperboard) about map projections called Map Projections for Babies. Presumably intended to be in the same vein as other board books on surprisingly advanced science topics (Chris Ferrie has a whole series of them; Quantum Computing for Babies is a typical title), Map Projections for Babies “explains how we unwrap the round Earth to make flat maps. This guide for babies (and their loved ones) describes a complex concept in kid-friendly terms. […] This project began last year, when I was inspired threefold by my daughter’s curiosity, my love for maps, and a growing number of board books that condense complex concepts for babies.” The Kickstarter was successful, the book is now at the printing stage and is on track for delivery in April; additional orders will be accepted at some point. [Geography Realm]

SMBC Takes the Mercator Projection into Its Own Hands

SMBC: Mercator
From “Mercator”, SMBC, 24 Feb 2020.

Saturday Morning Breakfast Cereal’s take on the Mercator projection is … not what you’d expect. The punch line is similar to Christopher Rowe’s short story, “Another Word for Map Is Faith”: if you can’t make the map conform to the territory, make the territory conform to the map. Since we’re dealing with the Mercator projection, this requires some … escalation.

Mapping the Canadian Election Results: Technical Details

Bothered by the widespread use of Web Mercator by Canadian news outlets to show last week’s election results, Kenneth Field has posted an article that aims to address the problem. Static maps of Canada tend to use a conic projection like the Albers or the Lambert, and that’s the case for print election maps as well. Online interactive maps, on the other hand, use off-the-shelf tools that use Web Mercator, which results in the sparsely populated territories looking even more enormous. But that doesn’t have to be the case, says Ken, who shows us, with a few examples, how use ArcGIS Pro to create interactive maps using a conical projection.

Meanwhile, Mark Gargul writes in response to Ken’s critique of his cartogram of the election results. Mark describes himself as an amateur and readily admits that other cartograms are “clearly more aesthetically pleasing. On the other hand, I was going for something different with my cartogram—specifically, to try to preserve riding-adjacency as much as possible.”

The other thing Mark was going for in his cartogram was to indicate the urban-rural split: metropolitan areas are given a black border: it’s easy to see which ridings are in Montreal or Toronto; seats that are partially urban and partially rural straddle those borders.

So it’s doing several things at once that may not be immediately apparent.

Previously: A Cartogram of Canada’s Election Results; More Canadian Election Maps.

More Canadian Election Maps

I hit “Publish” too soon last night. Kenneth Field and Craig Williams put together a series of maps showing the Canadian election results in a number of different ways: we have a value-by-alpha map, a proportional symbol map, and two kinds of dot density maps: one showing the winners, one showing all votes per constituency. (One dot equals 100 votes; the dots are spread evenly across constituencies, even when people aren’t. You can’t have everything.) And it’s on the Lambert, not the Mercator.

Speaking of the Mercator. Maps Mania’s roundup of Canadian election results maps notes that the Canadian media’s interactive maps (e.g. CBC, Global, Globe and Mail) invariably resorted to Web Mercator, largely because of the mapping platform used. (In-house infographics team? Don’t be ridiculous.) Web Mercator is singularly bad for Canadian election maps, because Nunavut: it’s the largest electoral district by area (1.9 million km2) and the smallest by population (31,906). It’s enough of a distortion on the Lambert: Mercator makes it worse.

As for cartograms, Ken hated the one I posted last night; Keir points to Luke Andrews’s Electoral Cartogram of Canada, which is a bit nicer, and uses only one hexagon per riding instead of seven. Keir also points to this animation that shifts between a geographical map and a cartogram. It’s hard to recognize Canada in cartograms, because it’s difficult for us to grasp just how many people live in southern Ontario.

Previously: A Cartogram of Canada’s Election Results.

Everything’s Coming Up Spilhaus

John Nelson

John Nelson reports that the Spilhaus projection will be supported in the next version of ArcGIS—version 2.5, to be released in a few months. This odd projection, which centres Antarctica on a world map showing the oceans as a single, uninterrupted body of water; went viral last year. Requests for ArcGIS support soon followed. Thing is, ArcGIS support requires the math behind the projection: figuring out that math took some sleuthing. The Spilhaus is, it turns out, basically an oblique aspect of the Adams World in a Square II projection.

Previously: About the Spilhaus Projection.

A Map Projections Roundup

Three things make a roundup. Here we go:

Here’s a gallery of all 68 map projections supported in ArcGIS 10.7.1 and ArcGIS Pro 2.4, from Bojan Šavrič and Melita Kennedy. Some interesting projections included here, some of which are only suitable for a specific region (such as the complex New Zealand map grid). No Gall-Peters, interestingly.

Chris Whong

Chris Whong uses a clementine as a substitute for Tissot’s indicatrix: “I found myself eating a clementine this morning, and thought it would be interesting to slice up the orange peel on an 8×8 grid to visualize how much of the earth’s surface is represented in WebMercator tiles at zoom level 3. This is kind of an inverse of the Tissot’s Indicatrix above, showing chunks of the spheroid’s surface over the projected tiles that represent them in web maps.”

Alberto Cairo’s short piece arguing that the Mercator projection isn’t a monstrosity doesn’t cover particularly new ground: the Mercator was created for a specific purpose (bearing-based navigation) and is a good choice for small-scale maps, but it has no business on a world map. But it’s probably worth reiterating, since I still see over-the-top condemnations of the projection on colonialist grounds, channeling Arno Peters (which, you know: not new).

Equal Earth Physical Map

On Sunday Tom Patterson announced that the Equal Earth Physical Map is now available for download in JPEG, Illustrator and GeoTIF formats. Unlike its political counterpart, no territorial boundaries appear on this map (though cities do). Not having borders doesn’t mean that Tom and his collaborators won’t get into trouble with the names of natural features, though: I note they use Sea of Japan rather than East Sea, for example (see above). But, importantly, they’ve released the map into the public domain: if you don’t like their labels, or their choice of cities or colours or textures, you can make changes to the map and put out your own version.

Previously: Equal Earth Gets a Wall Map.

Equal Earth Gets a Wall Map

It was announced today at NACIS that the Equal Earth projection is now available as a wall map—which is a necessary thing if it’s going to go toe-to-toe with the Peters map. The political wall map is only available as a download (three versions, centred on Africa and Europe, the Americas, or the Pacific): the 19,250 × 10,150-pixel, 350 dpi file results in a 1.4 × 0.74 m (55″ × 29″) print—assuming you have access to a large-format plotter. Not everyone does, so it’s only a matter of time, I suspect, before they have prints available for sale.

The map shows countries and territories in surprising detail (it includes Clipperton, for example); and while it does show disputed regions as such, its choices of boundaries and nomenclature won’t make it many fans in South Korea or India.

Previously: The Equal Earth Projection; Equal Earth Updates; More on Equal Earth.

About the Spilhaus Projection

Le Cartographe

This image went a bit viral earlier this week. Some context. It’s from an August 2015 blog post at Le Cartographe, in which Alexandre Nicolas discussed (and rendered, above) a projection produced in 1942 by South African oceanographer Athelstan Spilhaus. In Spilhaus’s oceanic projection, centred on Antarctica, the world’s oceans form a single, uninterrupted body of water. Which, you know, it is. The continents form the edges of the map; there is … some … spatial distortion. As Alexandre wrote in 2015, “This projection is rarely used and it’s a real shame!”

Previously: The Penguin Projection (speaking of Antarctica-centred projections).

More on Equal Earth

Equal Earth projection in colour

The Gall-Peters projection is a second-rate projection with first-rate public relations; cartographers’ responses to the projection that focused on its cartographic shortcomings ended up missing the point. Something different is happening with the Equal Earth projection, which was announced last month as a response to Gall-Peters: an equal-area projection with “eye appeal.” It’s getting media traction: the latest news outlet to take notice is Newsweek. So, finally, there’s an alternative that can be competitive on the PR front, without having to mumble something about all projections being compromises until the eyes glaze over.

It’s turning up in GIS packages, too: in D3, in G.Projector and in proj4. There’s even a t-shirt.

Previously: The Equal Earth Projection; Equal Earth Updates.