Academic parochialism

Last week I went to a schematic mapping workshop in Vienna, Austria. Schematic maps are some of my favourites and I'd used this opportunity to finally get round to developing my own ideas about a redesign of the London Tube Map. I'm by no means the first and won't be the last but after penning a discussion of what I characterised as the over-use, mis-use and abuse of Beck's original style from 1933 (The Cartographic Journal, 51, 4 pp343-359) it really was about time I put my money where my mouth was and had a go. The workshop provided a hard deadline and an impetus to make a map and throw it to the lions.

Me. And my map.

There were about 40 or so people attend the workshop. People came from a wide array of academic backgrounds - psychologists, computer scientists, graphic designers, cartographers and the transport industry itself. I'll be blunt. It was disappointing. While there were some interesting talks there was very little true sharing of ideas or development of collaborative opportunities. The cliques stayed within their own cliques and so the opportunity was lost. I displayed my maps and not one person wanted to actively engage in a discussion, or offer ideas for improvements. Having paid for the trip out of my own pocket that's disappointing. So what we ended up with was another example of academic parochialism at its worst. Niche groups striving headlong up their own small part of a much wider discourse and not really willing to engage beyond what they know or do. There were lots of words but not much else.

We had people focusing on usability, but not really appreciating practical implementation. We had people searching for efficient algorithms for label placement or line arrangement, not appreciating that many software packages already exist to do much of that heavy lifting. We had the idea that a fully automated map is difficult to create but never a real discussion about why you'd want that anyway. After all, maps are always made by humans to a greater or lesser extent. We had the idea that many who make schematic maps do so with design software. There was little from the GIS or data-driven cartographic community and no real appreciation of its existence or value. A lot of it was searching for a solution to a problem that isn't properly defined. It's low-level academic effort. The sort that keeps people busy but doesn't ever actually get anywhere purposeful. I know. I used to live in that world, and the further I get from it the more I recognise it for what it is and the more I am relieved to be out of it.

And the classic examples of 'research results' based on a survey of a group of students who are easy to cajole into research always has me raising my eyebrows. At best it's lazy, at worst, it undermines your work beyond it being useful. Of course students are likely to also be public transport users but they are not a diverse enough set of people if you want to capture the wide variety of people who have many and varied needs. I think we can do better. But there was also something else that made me think about the event in a way that I cannot ever recall feeling before.

I guess what I found most disconcerting is I felt like an outsider. This is a group founded and moulded by Maxwell Roberts who describes himself as "the world’s leading specialist in schematic map design". So, inevitably, there's going to be some disciples of his work in attendance and, as it turns out, all but 4 talks were 'invited'. Dr Roberts even took the floor twice for two 35 minute stints to bookend the event. Except I'm not one of his disciples. I like much of his work but ever since I wrote that journal article, Dr Roberts has made it known he took exception to my characterisation of some of his work as being unhelpful to wider debates about the value of Beck's work. To me, there's value in debate. Just because person A says something, person B does not have to agree. I used the opportunity to write a refereed paper that expressed my views based on the evidence I presented. In normal academic discourse, such views can and should be challenged. Different views expressed and published and so forth. But, it seems, this is not the case and it was unfortunate that Dr Roberts went out of his way to avoid me in Vienna. It's unfortunate but I can live with that. Should I have approached him? Possibly. But when you get bad vibes you tend not to bother in the interests of self-preservation.

Map Gallery at the Vienna Transport Museum.

There was a gallery of work on display at the Vienna transport museum on one evening. My maps were up there and earlier in the day I'd expressed my wish that people tackle them, rip them apart and let me know what they thought. I even wore my London Underground District Line Moquette shoes for some added interest. Maybe Dr Roberts would take the opportunity? Unfortunately not. Again, he went out of his way to avoid me (and my colleague Professor William Cartwright too).

Professor William Cartright and I at the map gallery.

I was going to leave it. If that's how these people want to work and (not) foster collaborative opportunities or, even, have a good old-fashioned academic slanging match then that's up to them. I returned from Vienna glad to have reconnected with some good friends, met a few new people and, once again, to have visited such a beautiful city. Except this morning I woke, to this tweet by @TubeMapCentral (aka Maxwell Roberts)

Any designer can create an attractive schematic map if the lettering is small enough, but it takes a very special designer indeed to create such a questionable schematic map with tiny lettering. Dr. Field should actually read the usability research that he is so quick to dismiss. pic.twitter.com/k8tKfymTCD

— Tube Map Central (@TubeMapCentral) April 14, 2019

So let's get this straight. Dr Roberts had every opportunity to talk to me last week. He had every opportunity to discuss my previous paper as well as my effort at making a map of the London Underground. But no. Instead, he posts a bitchy tweet (without using my twitter handle). It's a shame he didn't say my font was too small to me in Vienna because I totally agree with him. In fact, the prints were the first time I'd seen the work printed and my first reaction was the same - fonts are way too small. WAY too small. And this is the point of critique - to put your work in the gaze of your peers and others and to take on board comments and criticisms. A future iteration will address this limitation.

I wasn't going to write about my experience in Vienna but his tweet has me annoyed simply because he could have spoken to me in person. I should have seen the signs. Last talk on day one. My colleague, Professor Cartwright given less time than the other speakers. It all added up to support the fact that we simply were not wanted at the workshop because 5 years ago we had the audacity, the sheer temerity to offer some critical thoughts on some of his work as part of a wider debate. Yet they took our registration fee quite happily to boost numbers. If you're going to marginalise people then do so with class. But it doesn't achieve much. It narrows your potential for considered debate, albeit some of which might be challenging, but which ultimately strengthens a discipline. I don't like some of his work so therefore he doesn't like me. Makes sense eh? Not to me it doesn't. Tweets are cheap. I know, I send enough of them! But having had the opportunity to tackle me about the 2014 paper, or even chide me for my amateurish effort at tackling a really tricky map he, instead, waited until there was no danger of discussion. Ahh well.

What I did find of immense value at the workshop was listening to a presentation by the train manufacturer Siemens along with those at Wiener Linien who are exploring their cartography in relation to real needs, namely to fashion maps for a new generation of trains. So they are getting on with the job. We weren't allowed to take photos and I should probably not say too much as the work is currently not public and remains confidential. Except to say, they are experimenting with some really innovative animated maps. These go well beyond having a simple animated symbol that shows where you are on the route. There's morphing of the map under particular circumstances, changes to content depending on location and conditions, focusing of detail to serve the needs along the route, and real-time information delivery that goes way beyond simply showing train times and connections. I've honestly not seen anything like it and had a wonderful chat with the people behind it. These are the conversations you enjoy and ones which take you forward. The small-mindedness of a few has not detracted from my experience of this particular work and the potential it offers.

This, to me, also shows where we are in terms of who is driving research these days. Industry has overtaken academia in many fields. Cartography is one such field. Small groups of people doing very niche academic research into aspects of map design are becoming unimportant. And I think that's why these sort of workshops become increasingly frustrating. They aren't really helping move things forward, certainly not with much pace. There's too much reinvention and no real cohesion. They seem to exist to further one or two people's aspirations for relevance, rather than a sustained research agenda that feeds into real implementation. And along comes a train operator who, along with their customers, defines a need, researches it, and develops a solution.

I expressed this view earlier in the day at an 'open mic' slot where I used 10 minutes to play devil's advocate. In 2005 Google both decimated and utterly reinvented cartography. Since then, most transport networks persist with their schematic maps yet I contend that people are more interested in travelling between places of interest, not station names. Of course, this goes against Harry Beck's principles that above-ground geography is unimportant to the traveller but I think times have changed. So, for instance, if I'm in London and I want to travel between the London Eye and Selfridges how do I work out my route? I open Google Maps and I type in directions. I would suggest most people will likely do the same. In fact, I cannot recall the last time I actually saw someone use a pocket London Underground map. And even if I did I have to know where the two points of interest are in the first place and relate them to the location of stations. That's often very difficult with a schematic map. And yet Google Maps returns the optimal route (walk to Westminster station and catch the Jubilee line to Bond street). It gives me real-time train arrivals, journey time, walking routes to bookend the tube journey, as well as bus alternatives, and it now even tells me that a Lime scooter is nearby and could be quicker. The map zooms to become hyper-local. We see the actual location of station entrances so we can relate our geographical surroundings to where we actually need to go. And the map has the geographical tube network overprinted. So, my assertion is that, in 2019 the schematic map as we know it and love it may be dead. People use their smartphones and Google Maps to do their journey planning. It may well be the case that the printed schematic map has been killed by Google. Maybe this is what upset Dr Roberts? I don't know. I don't particularly care.

Unfortunately, in retrospect, the workshop was simply about his self-promoting academic parochialism. I'm glad I'm out of it, and Max, if you're reading this, please be assured I'll not darken your door at the next workshop. But I will be buying your next book on airline schematic maps because I'll likely very much enjoy it.

Professor Georg Gartner and Dr David Fairbairn discuss the Vienna map.

Update:
Unfortunately, Dr Roberts has decided to double down on his twitter rant.

Dr. Field's opinions about schematic mapping are questionable because he does not have an intellectually defensible, coherent theory of effective design. You can see that from own creation. In fact, I am not even sure he understands what the issues are and why they are important. pic.twitter.com/jvTNTXeF82

— Tube Map Central (@TubeMapCentral) April 17, 2019

Seems a little unfounded to me but I made the point that the opportunity to discuss, debate, argue even, was last week. Why didn't he take the opportunity to have me on a panel discussion for instance? Or even have a quiet word with me during one of the breakout sessions? It's not unusual for people who are passionate and knowledgeable about a subject to sometimes disagree but the art of academic discourse is to attempt to appreciate other people's perspectives. If you are closed to that, and wrap it in unsubstantiated personal attacks then you are doing yourself a disservice. I am concerned for his students if this is how he fosters discussion and engages in debate. It also reflects poorly on the University of Essex if this sort of approach to academic discourse is in any way supported.

Bend it like Mercator

After their win in the Champions League final yesterday, the 101 Great Goals blog published a piece on the relative location of FC Barcelona's triumvirate of South American strikers. They picked up a map from Reddit that showed their birthplaces as being positioned in such a way that you can draw a perfectly straight line between them on Google Maps.

Here's the map:

A headline writer's dream...arguably the three best strikers in the world all born in formation as well as playing in formation for the world's best team. An easy map to make...take a pen and draw a line across the map to link three red symbols, each of which is about 50 miles in diameter in real world units. Job done.

Except the map is incorrect...which makes the headline potentially incorrect too. A straight line between two places on the globe becomes a curved line when projected using Web Mercator (which the Google Map used by the author is in this case). You cannot simply draw a straight line on the map and infer that it represents a straight line on the curved surface of the globe - because it doesn't.

Here's what the line looks like on a virtual globe as if looking from Messi's birthplace to Neymar's birthplace:

And when we place that line back onto a projected flat map, here's the outcome:

The line now has a slight curve to it but with symbols about 10 miles in diameter it still just nicks the edge of the town where Suarez was born. If I'd used smaller symbols I could have shown the line doesn't pass through Salto, Uruguay. If I'd used big red blobs like the original then of course the line would pass through Salto. Built correctly, we not only get an accurate map...but one that supports the story even better!

OK, we're talking small margins here but the author of the original map got very lucky simply because of the quirk of geography relating to the three players he chose to link on the map. Because the three locations are relatively close to one another (in global terms) and they are also only 30 degrees or so south of the equator we don't see a massive distortion in the line. It has a curve, yes...but only a slight one.

But what if we look at three other footballers? Wayne Rooney was born in Croxteth, Liverpool. Harry Kewell in a Sydney suburb in Australia; and C. V. Pappachan, the famous (?) former Indian footballer born in Thrissur. Here's their map:

As far as I know there is nothing at all to link these three footballers but if we'd taken the mapping approach used to link Barcelona's strikers we'd also get a perfect straight line passing from Liverpool in the UK, all the way to Sydney, Australia via Thrissur on the southern tip of India.

If you got in a plane and flew the straight line route between the UK and Sydney the closest you get to Thrissur is about 2,500 miles. The red line shows the planar version of a straight line projected on Web Mercator. I included the Barcelona striker's line for scale which shows that smaller distances, particularly near the equator, 'appear' less curvier.

News aggregators, blogs and, well, pretty much anyone should question maps. They lie. They are terrible at telling porkies. Worse. Most map readers don't know they're being fed a lie because they look authoritative; and they don't know that the maker of the map they're looking at didn't know the pitfalls of their approach either.

As it turns out, Barça's strikers do happen to have been born close enough to almost lie in a straight line on the globe and on the map. The curve on the projected map tells the accurate story. Try telling the story using three other footballers who appear to have been born along a straight line on a map and chances are, they weren't.

Hat Tip to Brian Timoney for the tweet about this map.

Colour me bad

Cartographers have often been accused of doing little more than drawing lines and colouring in. It's a rather negative and stereotyped perception that fails to acknowledge the many different aspects of the job of making a map or indeed, to what purpose the map design is intended to support.

I've therefore become concerned at the growing trend of maps that appear to be created simply to showcase, how do I put it, drawing lines and colouring in. Most of us probably had paint-by-numbers kits as kids but we grew up and started with a blank canvas which was far more challenging but ultimately, more rewarding. Cartography has regressed to paint-by-numbers. People no longer start with an empty canvas. Having the data and colouring in tools is so useful in so many ways but for far too many it's just an excuse to do some mapping by numbers. We're not being stretched to think about the map any more. We're simply putting together component pieces from others and painting them in different ways.

Take the following examples which have garnered much love on the interwebs. I'm deliberately not naming the authors and I have no particular issue with the end products because on the whole, aesthetically, they work as pieces of art. But do they work as maps? I think they're illustrative of a paint-by-numbers craze in modern cartography.

One of the major requirements for a map has always been base data to give context, situate our own data or simply to indicate the pattern that humans make on the natural landscape. Over the past few years acquiring base topographic data has become ridiculously easy through the many open and paid-for suppliers that exist. Many of these come pre-styled into designs that support a variety of uses. Many of them can be re-styled using a number of different approaches. The processes of data collection, processing and generalisation are largely ignored by today's modern map-maker. Instead, they simply regurgitate other people's data and re-style to distinguish their map from everyone else's maps. The maps above then leave it at that. They go no further and they offer no clue as to what their eventual purpose might be other than as an example of painting data.

The result of all of this artistic expression is simply that we're seeing an awful lot of re-styled versions of the same data. They are painted maps in their own right but what function do they support beyond that? They appear to exclaim that form is the end-goal and function is all but forgotten. Pretty yes, but none of the maps you see above can really be used for anything purposeful. The balance between figure and ground is so often forgotten in many of these re-styled maps as well..and the typography is often poorly integrated. Putting our own data on top of them would be pure folly.

The maps are fun it’s true. But is the exercise of colouring in data doing anything to enrich cartography? In its simplest form we're using freely available vector data, popular and widely available design and production environments and then, well, changing the colours of the vectors. What does this prove? It proves we're able to find the RGB values of some inspirational art or colour schemes from nature and then change the map data accordingly. This is nothing more than buttonology – a longstanding issue, debate and criticism of digital cartography and geo-technology in general. We're losing our ability to understand the structure of the data in a cartographic sense or to wrestle with it in conjunction with typographic elements, layout or thematic overlays. We're losing our understanding of cartography.

Of course, we've been conditioned to accept that a pre-styled base map is adequate for making maps. How many maps do you see where someone puts a choropleth on top of a topographic basemap for instance? Using topographic, or reference, base maps just makes no sense for thematic cartography but it's an easy solution because it requires no effort. Actually, getting the balance between base and theme, ground and figure does require effort and should be part of our concern as cartographers. Effort is required. Effort should be rewarded but I see far too many of these painted maps get accolades they scarcely deserve.

Painted maps tend to show little cartographic quality. The re-painting of the data only illustrates the map-maker's ability to use a piece of software. There's no real generalisation of the data; selection of data or omission of clutter. There's hardly any graphical hierarchy built in to the map or emphasis on how colours interplay between symbols or across the map. Random features get symbolised in bizarre ways simply because the data exists so it should be coloured. How could the lines be simplified or exaggerated to the extreme but still give us a sense of the map? How might clarity or legibility be changed and to what extent? Is it possible to invert the data in a visual sense or play with the layout in ways the riff off approaches in art more generally? And what happens when you zoom in or out of the map...does the style update as the data is progressively generalized or modified at different scales? Rarely does any of this happen. We simple get more of it at larger scales but there's little nuance to the way the data is portrayed.

A lot of art deconstructs images and objects. Think of how Warhol approached bananas or a tin of Campbell’s soup or a picture of Marilyn Monroe. His art was to express the figure of his work in a new, different way. Re-colouring data on a map doesn't go far enough. It doesn't show any sense of design acumen. Maybe I'm just getting bored of all the so-called re-imaginations of map data but where is the originality? Where is the expression? Where is the cartography?

It's always nice to play around with maps and experiment (I do it all the time) but at some point we've got to go beyond being seduced by the technology and get back to understanding of the map and the relationship between aesthetics, form and function. Learning to change the appearance of symbols is good. Goofy and experimental mapping is also good. 'Goofy and thinky' is, to quote Hannah Fairfield (of the New York Times at OpenVis 2015), far better.

It’s the thinky bit that I feel is missing from this type of work and that the seduction of being able to use the data and do something to it relatively easily is what counts for many. Over the last ten years or so, the shift in time from having to collect and process all this data before you can even get to styling it has been profound. Someone’s done all the hard work. Actually, millions of people have done the hard work. Isn’t it incumbent on us to honour this work and take it further than simply painting it?

I think this sort of work might be generally called inconsequential cartography. I’d like to see more consequential cartography. I’m all for playing with the map in artistic ways but take it further. Make a statement. Make it say something. Make it work in concert with some other data to create a map, rather than just changing the basemap. Give it a real purpose. Give it a context. Marry the playful form with a function.

The cartography of Luminocity 3D

I've just had a good look at Luminocity 3D by Duncan Smith of CASA, Bartlett UCL. I'm impressed.

Web mapping is beginning to show signs of getting beyond the infantile and maturing from its pubescent phase and this example shows what can be achieved when you consider the entire user experience.

The maps are clean and well produced and there are plenty of them to support the inquiring mind, each accessible from a sensible tabbed box in the upper right. There's a permanent legend in the bottom right with not only a clear illustration of the chosen classification and shading schemes but a short description to assist interpretation. Nice to see data attribution and sources cited too. The title panel is sensible and although containing all the usual share and contact buttons is relatively unobtrusive. The graph in the bottom left is a masterstroke - it's linked to the map so we get a good scattergraph overview of the data distribution. Hovers provide the data summary and clicking a component in the graph orients the map appropriately. I really like the use of subtle graphical cues such as a slight animation to show an active element, or the emerging horizontal or vertical lines to anchor your eyes to the x or y axis. Likewise, hover controls on the map also deliver data summaries and the addition of a graphical yellow glow also gives focus. The ability to switch labels on and off easily also gives both unencumbered and contextual view of the map.

I also like the use of data re-apportionment into a consistent regularly tesselated grid which overcomes the problems of trying to use different geographies. It also makes moving between maps easier and supports visual comparisons more readily.

All that said, I'm going to get picky (because that's the purpose of the blog). I found myself frustrated by some of the cartographic choices.

Firstly, while diverging colour schemes tend to make a map look more interesting (more colours) it doesn't fit the data in a cognitive sense. Most of the datasets would benefit from a single hue progression or similar. Most of the variables are mapped with some arbitrary break defined where one colour morphs into another yet the importance of that critical middle value is never established. Is it important? The use of a diverging colour scheme suggests so but it is unlikely.

In fact, perusing through the maps shows an inconsistency in the graphical treatment. Most are diverging, some are single hue, others are multi-spectral (agh!).

Second, while the use of a regular grid is great the use of 3D on most of the maps is distracting. It's effectively a plan oblique representation of the hexagonal grid using a second variable to map population or employment density. Fine in principle and allows the map to remain planimetric (thus preserving scale across the map) but where you see large numbers of tall prisms it inevitably obscures a lot of detail behind. Prism maps have always suffered this limitation and I can understand that mapping the second variable gives us an important additional piece of information but it's questionable whether the cost of occlusion warrants it. The answer would be to include an ability to view the map from multiple orientations either through a rotate tool or just giving us, say, four of the cardinal compass directions. At least that way the map reader can see what's behind a block of prisms through map interaction.

Finally, the map works on multiple devices and some of the overlying boxes can be minimized - but not all. This does create a cramped feel on some devices and it would be nice for there to be more control over the position and visibility of these.

Like I said, I'm being picky but I'd like to see the cartography match the levels of the overall app, particularly in the use of colour.

Pretzel crust cartography

I saw an ad on television last night that may help the understanding of how cartographers think about good map design and construction vs what we perceive as poor map design and construction. It was for a new Pretzel Crust pizza available at Little Caesars. It's constructed with a pretzel crust as the base (poor basemap for a pizza in my opinion) and then goes on to slop on a thick yellow cheese sauce instead of a tomato based sauce (odd choice, gloopy and lacking taste), before topping it off with four more cheeses and pepperoni (solid choice for a final topping but a bit out of place on the base).

Take a look and you decide whether any of this should be allowable on a pizza. The pizza appears at about 16 seconds...by 20 seconds I'd hope you won't want one...by 26 seconds I'm hoping you're wondering what the hell they were on when they invented it. If you're thinking yum, gotta go get one now then you may as well not read any more of this post.

Want a pretzel? Have a pretzel. Want cheese dipping sauce with your nachos...go ahead (though forgive me if I don't - plastic orange goo isn't that appealing even in it's correct environs). But designing a pizza using these ingredients just doesn't work for me. If it was experimental then fine...but don't release it and ask people to pay for it. I wonder if I'm alone in this or whether sales prove otherwise?

There are clear parallels to mapping. Start with any old basemap - probably a default topographic one because you don't know what the others are for or, even better, use a satellite image because that's colourful and detailed and more must be better. Then slop some data over the top. Don't pay much attention to symbol choice or design...just dump your data across the top and smear it around. Actually, make it bright because it won't show up on the satellite basemap unless it's bright. Then if you have some point based ingredients (e.g. emoji...see previous post), position these across the top. Finish off with a smear of butter and a good dose of flavour enhancing salt and boom - you made a pretzel crust map.

On emoji cartography

Thinking of putting emoji on a map? Please don't

Whatever you call them: pictograms, pictorial markers and mimetic markers have always been hugely important in cartography. Well designed graphics that are used to represent a point of interest are fundamental to topographic mapping in particular but have become vital for web maps that show points of interest across a basemap. They should be clear, unambiguous and allow us to efficiently communicate the feature with simple graphic clarity. They should work in harmony with the rest of the map and subtlety often leads to a well balanced overall map.

They're not easy to design though. You're often working with a very restricted size, perhaps pixel count and, ordinarily, a single colour. With all those constraints it's often difficult to imbue symbols with the meaning required if the intent is to support a map reader's ability to understand the feature without constant recourse to the map legend. This reason alone is why it's more common to use pre-defined symbols delivered as part of your software or available online. There are perfectly good repositories for symbols (e.g. Symbol Store, Maki) but what about emoji?

Emoji - the Japanese pictographs which have become standard in electronic messaging. They're increasingly used as shorthand for all sorts of communication.

Their increased use doesn't, however, mean they are well suited to being placed on a map. Take a look at this map, made by Katy DeCorah (click to view the live map as part of Katy's blog).

Katy's blog entry explains she was interested in exploring a technical challenge, and she succeeded. But what of the outcome? Once the technical challenge had been achieved we still need to consider whether it's useful in a cartographic sense and in this case I'd suggest it isn't though Katy did at least use a limited set of POIs and did a good job of picking an emoji that vaguely represents the feature being mapped.

In general terms these sort of symbols create disharmony. The emoji are too detailed, too colourful and too 'cartoony'. They inevitably clash with the background map and where they begin to coalesce (as they will in a multi-scale environment) they become impossible to decipher. Their style doesn't suit most cartographic work unless you have a very specific mapping project...perhaps a large scale children's atlas. They simply don't look good on a map. For balance...there are other cartoony symbols that I'd also vehemently discourage in cartographic terms. Such as:

One of the tenets of the cartographic design philosophy that I was taught was to keep things simple. The KISS principle (Keep It Simple Stupid) holds true for 99% of cartographic tasks. The best advice any budding cartographer can heed is to learn how to be comfortable omitting detail in terms of the overall map and also the individual elements. Creating clean, simple lines leads to a much more harmonious map and one that is, crucially, much easier to disantangle and read. Symbol design goes a long way to creating that harmony. Just because a set of symbols is technically capable of being put on a map doesn't mean they should be.

Slopping emoji (or other 3D style, multi-coloured, shaded pictorial symbols) all over your map just doesn't work. Use them in your social messaging where a single emoji is often added as an exclamation or to characterise an emotion. Please don't use them en masse on a map...it hurts the eyes and as Kirsten Dunst might say, it's just a piece of poo (ht Craig Williams).

Voronoi treemap maps

The New York Times flexed their considerable graphic muscles this week with some superb interactive charts showing how the population composition of U.S. States has changed over time. You can check them out here.

They really are beautiful graphs. Simple, clean, lots of 'white space', good hierarchy of typeography and excellent use of colour linking to a small map legend. They even provide some additional discussion and as you hover over the graph the intersection between time period and place gives you some basic metrics.

They then added to this excellent set of graphs with an interactive map of the same data; a new kind of map that they're calling a voronoi treemap map.

The data has been pivoted so the focus is on space in contrast to the focus being predominantly on time in the graphical representation. You can pick one of three time slices to explore how patterns vary spatially. The hovers still work extremely well and one click zooms to a state...great user interaction and experience. The benefits of looking at a map instead of the graph are that it should support the visual comparison from place to place. That's not something you can do with the graphs with each one only illustrating a single state...but what about the map?

What fascinated me about the map is the technique. The use of voronoi polygons to sub-divide space into a tesselation of shapes that represent different proportions is nothing new. Treemaps are also nothing new and have been used very successfully as a sort of area-based cartogram. Here, though, NYT have combined the techniques and used a bounding space (each State) inside of which space is tesselated based on the proportion of the population from different other places. It's not something I've seen before and it's always worth looking at experimental cartography.

Does it work?

I like the idea and I like the attempt at trying something new. However, I see two issues that I feel undermine the map and what it offers.

Firstly, the voronoi polygons are only proportional intra-state and not inter-state so you get polygons with the same percentages of populus that are visually quite different to polygons with the same value in another state (see Texas compared to Oklahoma state-born residents, both 61% but one visually dominates). The point about putting anything on a map is to create visual comparisons and the voronois are, effectively, unequal in area from state-to-state so incomparable visually. The relative areas of each state underpin what we see. Since we're visually comparing one place to another and forming a mental picture at first glance Texas would seem to have a larger number of State-born residents than Oklahoma. I'm not sure there's an easy solution unless you turn the voronois into a population-equalizing cartogram (e.g. the Gastner Newman) to account for the different sized areas. It'd certainly be interesting to see what happens if they were equalised by population or area.

My second observation is really just about the design and layout. In each state the surrounding voronoi fragments seem to be randomly positioned around the central voronoi polygon that represents the people born in-state. If you look at the small legend map on the graph version you see that the orange, green, blue and pink colours are used to suggest west, south-west, north and north-east. It would have been nice if the surrounding voronois were arranged so they sit on a compass direction to where the state actually exists. So for each state the oranges would always be on the left, the blues to the north etc. This may bring some sense of structure to the map and avoid the somewhat random positioning we currently see.

Overall I think there's a lot of merit in this new map technique but it probably needs some more thinking to make it really useful.

Web Mercator and Comparisons

Getting the curved surface of the earth onto a flat map (paper or screen) requires a map projection. The reason so many projections exist is because there is no perfect projection and they all contain distortions which affect area, distance, shape or size...and distortions vary to different extents across the map.

While for most people, the often complex mathematics of transforming locations to the map is beyond their expertise it's important to pay some attention to the choice of projection. Choosing an appropriate projection is vital to ensure that the inherent distortions don't wreck the very purpose of your map.

Let's look at one example...say, for instance, you were wanting to create a map which allowed you to compare the areal extents of different cities across the world. You might want to see how one city compares to another in terms of the amount of green space, or the population density in urban areas. The one thing, the only thing, you need to get right is the choice of a projection that supports visual comparison. You need a projection that does not distort area...because area is the one property of the map that supports the cognitive process of visual comparison. Let's see this in action...

We can see what happens to distortions when we overlay Tissot's Indicatrix on the curved surface of the earth. The Indicatrix is simply a grid of equally sized circles (on the globe) which are a very familiar shape which makes it easy for us to see what happens when it gets distorted through projection. When projected, the grid of circles of equal size, shape and area are distorted which gives us a clear indication of what happens to the real geography that gets projected at the same time.

Tissot's Indicatrix on a globe:

Here's what happens when we project to Web Mercator, the default for web maps:

Web Mercator preserves angles (which is why the circles retain their shape) but distorts size, and, fundamentally, area. It's great for navigation (its intended purpose) but dreadful for most other purposes.

Now let's compare the two cities marked on the map...Oslo and Singapore.

Oslo is at 60 degrees North. Singapore is pretty much on the Equator at 1 degree North. There's virtually 60 degrees of latitude between them and looking at the two Tissot Indicatrix circles they fall in you can see the distortions that Web Mercator creates in the size of area between the two places. If you examine the size of the two circles you find that the Indicatrix around Oslo is approximately 75% larger than the one around Singapore.

Let's have a look at the impact on a real map. The following maps are on Web Mercator and both at a scale of 1:250,000. Oslo on the left, Singapore on the right.

Now let's look at exactly the same map but projected using a Cylindrical Equal Area projection. I've switched the standard parallel to 60 degrees North for the Oslo map just to ensure the shape isn't distorted compared to Singapore but areas are consistent between the two maps. Now compare Oslo with Singapore.

Oslo is now shown at the correct areal extent and size compared to Singapore. The distortions you see in the size of text etc is simply because the map tiles used to display this were originally in Web Mercator...so the fact they are now reduced in area by about 75% actually results in the map looking like it's shrunk. It has! It also shows how much Web Mercator tiles are distorted in terms of area the further from the equator you go.

The answer...pick the right projection for the right job. You can go beyond Web Mercator on a web map so it's just a case of figuring out how to do it using your technology of choice. If you're going to be comparing areas either for city comparison or for thematics you really do need an equal area projection unless all of your cities sit on the same degree of latitude. If not, you're literally pulling the wool over the eyes of your map readers and they leave with a totally distorted impression of the themes mapped.

Next time you look at a map whose purpose is comparing places just pause to check the projection and then make your own decision whether you can trust what your eyes are telling you.

Testing..testing...1, 2, 3.

I was reminded this week of a number of ways in which you can assess cartographic work in simple ways. A conversation between Alberto Cairo and Moritz Stefaner trod over some old ground but their conversation is worth exploring because much of what I see fails these simple tests (and leads to me blogging). They debated the first and second of the simple tests I set out below. I added the third. These are tests that I (and many others) apply when looking at and critiquing maps. They are the basic tests that anyone can apply:

So What?
The first test is simple...does the work you are looking at leave you asking so what?. This is how we used to assess student dissertation proposals and get them to reflect on whether their proposal was worth doing. Was it persuasive? Did it make me want to know more...to explore or find something out? Did it make me care? All maps ought to, at some level, inspire their intended audience to want to care about what it is that's being illustrated and the message of the map. It has to have a function and if the form is well crafted that function should be visible. The map may very well have a good purpose to the map-maker but has that been extended to an audience?

This isn't an exact science though. Different people and user groups have different so what thresholds and so what works for one may not necessarily work for another. This is where a consideration of the audience comes in when you are making a map. Engage your audience first. Bring along others if you can. Pleasing everyone all the time is impossible though.

It's also perfectly reasonable to experiment and at the moment we're in a period of cartographic development where technology is out-pacing best practice. Animation and 3D are just two areas that we've always played with but now the tools are mature enough to allow people to really get their hands dirty...and they are. At the moment there's too many failing the so what? test. This may not be a bad thing IF it leads to new ways of working that make good use of the techniques.

Ah-ha!
Let's assume people have got past the so what moment because, let's face it, if they haven't then they've already clicked to another web page or left dissatisfied with your work. Upon inspection, does the map give you some sort of mini-eureka moment? Is the message communicated with clarity and has the map-maker made it legible? Clarity and legibility are key though they are not the same thing. Clarity relates to the message. Has the message been encoded into the map's syntax effectively. Legibility is the way in which the map-maker has brought focus to that message through effective graphical structure.

Put simply...do you get it? This is the ah-ha! moment when you realise what it is you're supposed to learn or find out. It should come relatively easily.

The person that reads your map should leave with a deeper understanding of the theme or topic. They shouldn't have to work too hard to gain that understanding either. The ability of the map-maker to make you care enough to want to look at the map and give you some sort of clarity about a topic is what good cartography is about.

The squint
Does the story of the map immediately jump out at you? Given we cannot rely on people spending that much time or effort viewing your map, making the message legible is crucial and this has a lot to do with your ability to structure your map. This is down to what British geographer William Balchin termed graphicacy. He coined the phrase in a 1972 address to the Geographical Association. Graphicacy is the natural counterpart to other cognitive intelligent processes of communication such as literacy, numeracy and articulacy. Maps and other spatial documents are the tools of graphicacy and the very basis of geography. Cartography is the professional application of expertise in graphicacy.

Becoming proficient in graphicacy will help you tell your story more effectively in the same way that effective writing or speaking skills helps you communicate using the written or spoken word. If you know how to speak in a graphical language then you're half way to being able to communicate your message. This goes beyond knowing constructional techniques and mechanics for knowing how and when to use certain graph or map types though. It's just as much about how you organise them on the page or screen. While written and spoken language comes at us in serial...one word after another in a sequence that our eyes follow and our brain systematically decodes, pictures arrive at our eyes in parallel. Maps are presented all at once. So we need to encode them so that certain components appear more prominently to give our brains a chance at decoding into some sense of order. These lead the eye. they may be larger or more visually prominent, they may use lighter or desaturated or bolder or more saturated colour, they may appear in a certain animated sequence or they may require interaction but doing a squint test is a good way to determine whether what you are looking at is communicating well.

So...sit back as if you're in a wild west film, chewing on a cheroot and pretending to be Clint Eastwood. then squint and look at the map. What do you see? If you can still make out the main features and the central topic of the map then chances are it's got its graphical structure well proportioned and balanced. It's a simple way of seeing whether what you are seeing is what your brain is receiving. If your eyes are picking out peripheral or less important components under this test then that's going to cloud the message. There is some science behind this...what you're doing when squinting is reducing the amount of light entering your eye. Your peripheral vision is also impacted. You therefore have lower levels of visual acuity (visual resolution) and so you are trying your hardest to pick out key shapes and features.

And finally...some words from a master
As with everything, there will always be examples that break the rules. there will always be innovation that overrides some of this so be mindful of that when looking at maps. Also, remember that the value of a map is going to vary between audiences so that will undoubtedly affect your impression. Then there's the final matter of subjectivity. While the above are semi-objective tests there's no doubt that we all have preferences for certain types of maps and particular looks and feel. Do you prefer Monet, Turner or Banksy? We all bring our subjective preferences to the table.

In the week that the great designer Massimo Vignelli died it's worth reflecting on some of his basic tenets in design and thoughts on why experts in a field are important in the context of shaping best practice. This gives context to the simple tests described above:

"I like design to be semantically correct, syntactically consistent, and pragmatically understandable. I like it to be visually powerful, intellectually elegant, and above all timeless."

"If you can design one thing, you can design everything."

"I thought that it might be useful to pass some of my professional knowledge around, with the hope of improving [young designers'] design skills. Creativity needs the support of knowledge to be able to perform at its best."

"If you do it right, it will last forever."

"The life of a designer is a life of fight against the ugliness."

"There is no design without discipline. There is no discipline without intelligence."

"Good design lasts longer."

"...and that is why I love Design."

The three tests outlined here are basic things you can do to see if your own designs are working and to look at whether other designs are working. It's not rocket science but it may just help you to take a step back and reflect on the quality of the work. There's lots of fancy ways to make maps but fundamentally...are they working?

Spreading Light, Wasting Light

This blog entry is about mapping, honestly...but to get to my point I'll start with Dave Grohl and then get to Robert Downey Jr and Steven Feldman...bear with me.

On a recent flight I watched (for the second time) the great documentary on Sound City studios by Dave Grohl. The iconic music recording studio in Los Angeles was one of only a very few in the world to house a custom Neve 8028 24-track recording console designed by Rupert Neve. It was a hand-wired analog device which acted as the interface between the musician and the tape used to record the music but it was the console that gave the end product such a rich, unique sound. Often, musicians would need to play their track over 150 times to get it as they wanted it with all the imperfections ending up on the tape. They not only had to master their trade but be dedicated to giving their best live performance that would become the recorded piece. With only 24 tracks available on the console, the producers also had to be prudent and understand how a complete track was to be constructed to achieve their intended final sound.

The story is ultimately one of decline of Sound City as a viable business (it closed in 2011) despite it being the birthplace of countless classic albums produced in the late twentieth century as digital recording appeared and along with drum machines and other digital instruments, allowed people to record direct to a computer. The benefit's of digital recording are clear - the entry level for people making and recording music are massively decreased; the costs are much lower to make a recording; and anyone with a computer can record music. By using a program like Pro Tools you can play a track once then work on your computer to change duff notes, alter the pitch, add a range of effects (curiously with an image of an effects pedal you'll never likely have even seen in real life) and record as many tracks as you care. In short, it's making music for dummies and we've seen a proliferation of music appear as a result, all of it seeking perfection through a processed approach. You actually don't even need to be a musician to make an album these days. No craft, no art, no expertise as such...just working with digital data that equates to music when processed in a particular way.

However, as one contributor put it eloquently, there's nothing of the musician in much modern digitally produced music. A huge amount is over-produced with multiple layers of noise. What made music recorded through the Neve board at Sound City so immersive was the imperfections; the fact that you're listening to a real person play a real instrument with all minor imperfections in their playing exposed. It gave the music a 'feel' and a human quality that is difficult to express but which can be easily heard. It's an audible aesthetic and one that cannot be replicated in the same way using modern technology. The same commentator went on to say that yes, music recording has opened up like never before but he challenged us to consider whether it meant there was any better music out there. His thesis was simple..that all that has happened is more people with a lower level of ability or understanding of music (playing, recording, producing) now make music - but that there's a much higher proportion of poor music as a result. It's harder to find the quality any more because quantity sells.

Back to cartography - but as anyone who has read my blog before will realise, the above tale is pretty much verbatim my views on a lot of modern mapping. The death of expertise and massively reduced barriers to making maps has given us quantity but has seriously diluted the quality. People are becoming blinded to high quality mapping because they're consistently told to go look at this or that 'great' map by people who probably couldn't tell the difference anyway.

So my latest gripe is with the plethora of animated maps of social media data that are using CartoDB's torque engine. I like what CartoDB are doing and their torque engine is a very simple way to animate time-dependent data. But what of the result - how is it being used? Take a look at the following map of how Robert Downey Jr's twitter account gained followers in the first 24hrs after his first tweet:

And the man himself even commented on the map:

Just spreading light. RT @TwitterData This map shows what happened to @RobertDowneyJr followers after his first Tweet http://t.co/EhmewFyAdf
— Robert Downey Jr (@RobertDowneyJr) May 13, 2014

So what does the map show? I think Downey Jr was spot on...it just shows him spreading light. Actually, it doesn't really show anything at all, except for twitter's absence in China. So a huge global movie star gains followers in places where people live. Are we amazed? And I'll not even bother to go into the pitfalls of the problems of mapping and inferring anything from Twitter data (because I've done that before).

Here's another of the tweets that were posted around the recent F.A. Cup Final between Arsenal and Hull City: Again...it's just flashing light. What purpose does it actually serve? Visually, I like the effect but it really only shows us that people tweet. And therefore tweets reflect where people are on the planet. And Arsenal are much more popular than Hull City. And perhaps my good friend Steven Feldman is the one responsible for lighting up the UK as a twitter loving Arsenal fan?

There's just nothing particularly substantive about making maps like this. Once you've seen one you've seen them all. The digital tools make making the map very simple but it doesn't mean we're seeing good maps. It's quite literally a data dump on a map. There's no sorting, sifting, no trying to extract an interesting story or communicate a highlight (no pun intended though this would be a useful thing to do!). Light is cumulative and brighter = more but why are we so fascinated by 'more' of everything?

When I look at the map I see flashing light but after a short while I lose sight of the light area (most tweeting in relative terms..and really, the only metric this map is capable of displaying) because the almost strobe effect of the single tweets in the sparse areas becomes more prominent. Is this really the right message? And when the map is saturated with tweets what are we seeing? Anything?

I find the story of Sound City and its demise in the face of the onslaught from digital music has many parallels with my area of expertise. Whilst there's no doubt making maps these days is massively improved on many of the older techniques it doesn't necessarily equate to there being better maps. Like Grohl, who is a master of his craft (whether you like his music or not), many musical experts can still find ways to make their music and embrace digital technologies as part of their workflow. Trent Reznor is also a perfect example of this. A musician who knows his craft but is hugely experimental and who can weave modern technology into his work expertly.

I'm not decrying technological innovation and progress - just lamenting the decline of the thought that people used to have to put into making a map. If it was worth making it'd take time...and so that cost alone was a good way to decide if making the map was worth the investment. These sorts of maps can be made in minutes but without any sort of cartographic craft you end up making maps of flashing lights that tell us nothing or, as the title of Grohl's last Foo Fighters record stated...you're simply "Wasting Light'.

Update 1: there was an interesting side debate on this topic where some were suggesting that frivolous maps are nice once in a while. I agree. Firstly that this sort of animated map of social media data is content frivolous but also cartographically frivolous. It's experimental and at the moment we're in a period of cartographic change where for the first time in a long time technology is outpacing best practice. Experimentation is good and we need to figure out ways to harness these new approaches and to develop new best practices. This is a challenge and one that cartographers need to embrace. Unless they do, all we'll see is more of this type of mapping and more people telling more people how great it is.

The worm is turning

This entire blog is a conduit to encourage better mapping by exploring and providing critique on the dreadful, the mundane, the inaccurate and the sheer bloody hideous maps that we sometimes see. It's about standing up for what's right in my area of professional expertise and trying to reassert the value of high quality cartography (even if it hacks a few people off...which it seems to regularly).

For a few years, the over 100 blog posts I've written have sought to explain why bad maps are bad and how they might be far more effective...but over that same period there's also been a dramatic increase in the proportion of poor maps and, more than that, a massive increase in the various media sites that regurgitate, promote and peddle cartocrap and which also contribute through their own less than optimal efforts.

But maybe the tide is turning? This week has seen two media sites post articles on the problems with online maps....that's right...the PROBLEMS with online maps. Music to my ears.

First, Ben Blatt at Slate wrote an article entitled "Bad latitude: The trouble with viral maps". Then Business Insider's Mike Nudelman and Christina Sturbenz got in on the act with "The internet is obsessed with maps - here's why it's gone too far". And what prompted all of this? Ironically, it may well be the NBC Nightly News map that caused me such ire I wrote my "Changing face of America" blog post which was then itself used as a basis for the article by John Brownlee in his FastCoDesign blog "The worst infographic of 2014 (so far)".

The Changing face of America cartofail was perhaps so awful it may well have jolted people to question what they see a little more; to not be so accepting of every map they see and promote to such huge levels of viral contagion. Maybe, just maybe, some have actually pondered why people like me get so worked up at what all too often appears to be the dumbing down of the art and science of making maps? Or maybe online media has just measured the pulse of horror over this particular graphic and this week we're seeing some sort of reaction.

There's probably something else going on...we're possibly just reaching a tipping point. Our social media feeds are absolutely saturated with maps. Really saturated. Just yesterday I saw these two awful efforts:

The first was actually from a 2011 article in The Atlantic by Richard Florida entitled "Mapping the anti-creative class" that I hadn't seen before (but in social media if something goes around once it inevitably goes round again and again). It's just an abomination. There's no cartographic control been applied at all. It's a load of map-like components dumped on a page. There's no thought to symbolisation, layout or meaning. But it wasn't the map that horrified me so much as the write up which began "Those terrific cartographers over at...". No...NO. This is not cartography. It's been made by someone who clearly shows no cartographic acumen. The reporter clearly has no background in assessing or justifying that comment. It's tantamount to libel to accuse the author of cartography.

The second is from an article entitled "This is what America would look like without gerrymandering" in Vox by Andrew Prokop. It offers a really odd (and methodologically questionable) way of redistricting the United States that is based on using an algorithm that splits a state in half using the shortest possible line...which they kept repeating until they had roughly the same number of districts as the 'real' map. They are pretty shapes but also pretty meaningless. By repeating the flawed approach they simply propagate the errors at finer resolutions.

All of these media sites have been guilty of promoting this sort of stuff. They scrape and aggregate then push it to the unassuming and the uninitiated. In a tiny corner of the world people like me voice our concerns but it's a hard fight against large, loud, noisy voices, likes, pluses and retweets. But what happens when the media get bored of writing the same articles? They tend to take the opposing view. It's a cyclic approach to reportage...it's how so much of news media works. They build something up then knock it down again because then they have something new to write. The 15 minutes of fame that people have yearned for by creating maps they simply want to go viral may just be about to end because the backlash is beginning.

There's something ironic about Slate and Business Insider beginning to take a different stand since they have been two of those media outlets more than happy to promote cartocrap in the recent past. I'm not going to quibble though - if they bring this message to more people who then take a more critical eye to their consumption of online maps then that is a good thing. They will hopefully start to become a little more discerning, more demanding. Up to this point, the media have stoked the production of awful maps because they've been behind their promotion. If they begin to take a different approach then maybe people will also begin to think more...to produce work of a higher quality with at least basic construction being applied sensibly.

Maybe I'm being a little altruistic. I don't for one minute expect a dramatic shift from quantity to quality. As someone who has, in a very small way, campaigned for better mapping across all facets of my professional and private work in cartography it's a shift I hope has begun. It's a huge ship to turn and there's always people who believe their own facts but maybe if the outlets they rely on to push their work change tack, they may have to revisit their own approach.

Hubble bubble, transparency and trouble

I recently wrote a blog highlighting the problems of using transparency on choropleth maps when they overlay basemaps. Mike Bostock's recently posted "Let's make a bubble map" provided a really great tutorial on thematic mapping but also highlighted the issue of transparency once again. Here's his final map:

Look nice? Well yes, at first glance it does. It's clean, modern and pleasing to look at...and remember, these days most people are only glancing at maps so that first visual impression is oh so important. It's not just about looks, it's about the message we see with our eyes and how our brains are interpreting it. The use of transparency on this map creates a confused message because at first glance do you see size as important or darker colours as important? Or both?

There's a trend in online mapping in particular that uses transparency as part of the symbology design at every available opportunity. Modifying the alpha channel can be extremely useful and gives us a huge amount of flexibility to design symbols that work, particularly given the interplay of often complex symbology that competes for space.  It also allows us to produce some really pleasing effects. The problem here, though, is that applying transparency at an individual symbol level means that where symbols overlap you get darker colours. That's not a desirable effect when we're trying to communicate something about a quantity represented by a variably sized symbol...because it communicates something extra that is meaningless.

A proportional symbol is really just a geometric shape that reflects the value of a point or of an area (represented by a point). The overlaps have no spatial meaning whatsoever. Cognitively, we begin to confuse out estimation of magnitude (by seeing size differences) with another estimation of magnitude (lightness or saturation of colour). The use of transparency here creates a pseudo-choropleth effect that demarcates areas of circles as different to one another in some quantifiable sense. It's like seeing a load of stacked Venn diagrams where the overlaps have some additive property we should be mindful of. Except overlaps on proportional symbols are merely a function of proximity of the locations as well as choices made about relative symbol size. Overlaps do not mark out special areas where 'more' of something exists.

It's a confusing visual message. Additionally, where we see a large number of smaller symbols overlapping a larger one, the overlapped transparency masks the larger (more important) symbol. Look at the difference between the areas around Los Angeles County CA and then Cook County IL. How many of us miss the large symbol near Cook County because of the overlapping smaller ones? - yet it is similar in size to LA County, which just doesn't have as many counties nearby so doesn't get swamped. The overlaps are far more prominent on the east coast than the west simply due to the geography of there being more counties...but the increased density that we perceive through overlapping symbols causes an additive colour effect overplay the actual data magnitudes. By using transparency we're adding visual heirarchy to the symbols that show smaller darker ones as more prominent. That's at odds with a map like this where larger sizes should be at least on the same visual level.

Bostock correctly reorganises his symbols so smaller sit on top of larger. Then, instead of using transparency there are two more useful ways in which overlaps are dealt with to avoid the problems caused by transparency. First, the use of a border the colour of the background of the map is sufficient to demarcate symbols by effectively using cut-out effects. The symbols remain on the same visual level so we simply see the relationship between size and value. Like this:

Alternatively, hollow symbols with a strong outline might be used. Again, this makes the symbols all sit on the same visual level so we see size of the symbol as the visual variable relaying the information. For this example, the sheer number of symbols may not make this as good an approach but it can be used to good effect in different circumstances depending on the relationship of the geography, data and symbol scaling employed:

Bostock does a lot of other good work in the tutorial, not least pointing out the benefit of a decluttered basemap, or that we may consider using population weighted centroids as well as the need for strong visual anchors in the legend. All solid advice. The final version of his map as a web map adds a hover tooltip and also highlights the county by changing the border to black - a very sensible approach to give clarity to what is selected and to use interactivity in a useful way.

While I'm writing this though...there's one other niggle I have...the name: bubble map.

The long-standing term used to describe this type of map is a proportional symbol map. Now before someone calls me out on this and points to the fact Bostock notes this clearly at the start and end of the blog well yes, he does (he also refers to it as a graduated symbol map which isn't quite the same). So why persist in pushing a new term when a perfectly good one already exists?

Charles de Fourcroy is arguably the first to use proportional symbols in a graphic to show demographic data (he used squares...in 1782). We had to wait until 1837 to see proportional width symbols used for flow maps (Henry Harness). It was probably Charles Minard who then used the technique of making a symbol proportional to a value as part of his differently sized pie charts to show the origin of meats consumed in Paris...in 1851. And map-makers have been making (and calling them) proportional symbol maps ever since.
I appreciate Bostock probably wasn't the first to coin the phrase so it's unfair to pick on this example but it's symptomatic of a growing epidemic. Bubble charts are not new. They're proportional symbol maps. How much more perfectly decent cartographic history and relevant terminology is going to be reinvented? The connotation with the word bubble is that the symbols are circles. It's true that most proportional symbol maps use circles because they are often the most suitable (as in 'the perfect shape'). But here's a version with squares:

OK, I'd agree it's not as pleasing for this dataset but it can have its uses. If and when you use squares, hexagons or any other proportionally scaled symbol to map thematic data do we have do call them bubble maps too...or maybe each map sub-type now gets its own name...squarey map?

Anyway, I digress.

Transparency is your friend as a map-maker, but knowing when not to use it is as important as knowing when it can really help your work.