Posts Tagged ‘unnecessary map elements


A Dollar per Square Meter

Today’s effort comes to my attention via a reader, Nicholas, who wrote to me early last year and suggested that I have a look at the following piece:

Click to enlarge

Click to enlarge

It was created by Chris Dickersin-Prokopp, who posted it on his blog and on Greater Greater Washington (where it got most of its comments) in February 2013. If you read the comments, you can see that, unfortunately, the response was not quite as positive he had hoped for. Not only did Mr. Dickersin-Prokopp accept the criticism gracefully, but he said he hoped that perhaps he’d find his way onto the pages of this very blog. So, let’s have a look.

To me, the real issue here is not in the map design itself, but instead the disconnect between the author and his readers. It’s an issue in any sort of creative field: you make something, and it turns out that the people who view that something were looking for something else. Mr. Dickersin-Prokopp’s detractors seemed to be looking for details on the map:

“Wow. I find it hard to think of a worse way to visualize these data. How am I supposed to draw any conclusions from a picture showing thousands of overlapping circles?”

“I can’t tell how many overlapping circle I’m looking at in different areas. Why not just make each sale a dot and color code the dots for different sales price ranges?”

But the author, I speculate, was trying to paint a broad picture: where, generally, home sales are more concentrated and more expensive. Counting individual circles isn’t necessary here. You just need to be able to tell where there are roughly more or roughly less. I think that his map does this job just fine, giving you the 10-second quick understanding of the basic pattern. His readers, however, were looking for something else: a map that let them break these patterns down in more detail, and count the number of houses in neighborhoods (everyone always wants to know what’s going on in their neighborhood/city/state when they see a map). The map isn’t ready to do that, as is, and the second quote above suggests a reasonable alternative. But one that, probably, wouldn’t have done as good a job at telling the quick broad story.

Two different ways of reading the same set of data: the big pattern, and the individual location data. The author had one in mind, but some of his commenters had another. What to do? Well, there may well have been a good symbology to satisfy both. But, setting that aside, how do we get people on the same page as us if we’re making maps? I think this map could use a little more context, to steer people’s minds toward reading it as the author wishes. Annotations would be handy—highlight some region or other and say, “over here, we can see a dense area of inexpensive home purchases that happened because of Reason X.” Get people thinking about the patterns and pull them away from the details that the author is less focused on.

The other option is to just change the map in response to comments, trying to give the audience what they’re looking for. It’s tough, as a creator, to have to give up on part of your vision and preferences, but it’s necessary if you want anyone to look at your creation. If no one likes it, then it doesn’t matter how great you think it is: no one is looking. Of course the hard part about that is that while many don’t agree with your choices, they don’t agree with each other, either. Some folks liked Mr. Dickersin-Prokopp’s effort:

“The message the map intends to convey is clear and obvious.”

If he changes things, he may displease some folks who were previously happy. There’s not much to be done about that, except to accept that you can’t please everyone.

Bigger picture aside, there are some other interesting things to dissect here, starting with the legend. which states, “Circle size represents sale price. One square meter equals one dollar.” If I interpret this correctly, this means that, in order to divine the sale price of a home you must determine how large a circle when compared against the map scale. That is, you pretend the circle is a real area of land in DC, measure the size of that land, and then convert to dollars. This is quite a fascinatingly weird way of explaining the symbology, and I’ve never seen anything like it. For good reason: it’s difficult enough so as to be largely useless. If you want people to understand what symbols mean, show the symbols; a legend should show more than it should tell. It would be better if this particular map showed people some sample circles and the values they represent. Then readers can reasonably eyeball things.

Typical proportional symbol legend designs. Via Esri Mapping Center.

Typical proportional symbol legend designs. Via Esri Mapping Center.

It’s highly unlikely that anyone is planning on measuring the exact price of each home (and if they do, they deserve what they get). We just need to let them get a rough idea of the pattern, and the circles above do that easily, without requiring people to visually measure square meters.

Speaking of which, that brings us to the scale. The increments could be a lot more helpful. At the very least, they should be in kilometers, but miles would be likely much more intelligible to an US audience. And the scale bar probably doesn’t need to be as wide as DC itself. No one is likely to do any measurements with it. To that end, I’d argue it could be dropped altogether. It is an unnecessary map element.

One Nice Thing: Putting your work out there for criticism and comment is tough, especially if you’re opening it up to the harsh gaze of the random Internet visitor. Mr. Dickersin-Prokopp handled the experience gracefully, and listened to the feedback he received, where I’ve seen other people in similar situations try to rationalize away criticism, or strike back angrily. Kudos to him.


Assembly-Line Map Elements

Gentle readers, my apologies for being so long in returning to blogging. Inspiration has sometimes been a bit lacking, and when it wasn’t, time was. But be assured I have no plans to abandon this enterprise without notice, though I may take breaks from time to time. I’m also hoping to bring back guest posts to keep things going when I don’t have the time.

On to today’s main event. This morning I received an email from a colleague pointing me in the direction of the GIS Lounge, specifically the recent post there entitled “Ten Things to Consider When Making a Map.” It’s a well-intentioned piece — many people out there who are just starting out begin with the question, “how do I make good maps?”, and there are several other forums and websites out there which give aid to the uninitiated. Unfortunately, the GIS Lounge chose to give the following as one of their pieces of advice:

6. Incorporating Map Elements

Making sure that all map elements are properly applied is important for providing readers with the context of the map.  All maps should have a clear and concise title, scale bar, and north arrow.

I can think of few more misguided statements about cartography. Longtime readers know that I am the head of the Worldwide Campaign to Eliminate Needless North Arrows, as well as the International Crusade Against Useless Scale Bars. Such elements often end up as no more than functionless clutter, yet we are told that they are mandatory all the same. If you click on the link above, you’ll be taken to the GIS Lounge’s list of “required” map elements (edit: shortly after I made this post, the page was changed to no longer call them “required”), including scale bars, north arrows, and legends. To be fair, the GIS Lounge is by no means alone in advising that there are certain things that every map simply must have — such declarations are unfortunately not rare. However, their “What’s in a Map” post is probably the most prescriptive one I’ve seen in a good while.

To begin, the entire concept of a list of “things you must do to make a proper map” is deeply, fundamentally flawed. It’s as misguided as a list of “things you must do to make a good painting,” or “things that make a good story.” Everything is contextual, depending on your audience, the message and mood you want to convey, how the work will be used, etc. It’s impossible to say something is required for every single situation. It’s not just the impracticality that’s a problem, though. The real issue is that such lists of “things maps must have” have their roots in a concept of cartography as a series of steps to follow or pieces to assemble, rather than a holistic art form or craft. Good maps are not made by following a simple mindless procedure or making sure you’ve ticked off all the boxes. That kind of attitude is how maps end up featured on this site. It’s also the only way machines can make maps at the moment, and it’s probably why they’re often so poorly done (see also this post I made on my other blog).

A list of requirements for how to make a good map is dangerous because it tempts beginners into shutting off their critical thinking and their creativity. Rather than consider why something should be done, or trying something new, they simply follow the list. I’ve seen it far too often in students. It also leads people to criticize and think narrowly about otherwise good maps because they don’t fit rigid expectations. Instead of a requirement list, I would say that the best we can do is simply give a list of things to think about when making a map, not things that must be done. To their credit, the GIS Lounge leads off their “Ten Things to Consider” piece with the caveat that these are simply suggestions, “a starting point of things to contemplate.”

Beyond the philosophical problems of actually having a list of required map elements, there are issues with the specific items on the list. Namely, not all maps actually need these elements. Let’s take them one at a time.

Title: Most maps do probably need titles, but it really depends on the context. Something sitting in the midst of a textbook page may have an explanatory caption, instead. A well-done legend often explains what the map is about as clearly and as quickly as a title, as well.

North Arrow: Most maps don’t need a north arrow. I honestly cannot fathom why they are so popular. Consider the following map:

From the US Census Bureau, via Wikimedia Commons

It has no north arrow. Most of us can recognize the United States, and we’re able to, say, determine that Texas is south of Minnesota. Even if we weren’t familiar with the area depicted, we’d probably assume north is toward the top (and, if it’s not, then a north arrow becomes a much more necessary element), as that’s the common convention we’ve learned. But what if you didn’t know this convention and honestly weren’t sure about which way was north? How would you possibly orient yourself? Well, you probably don’t need to. You’re probably not planning on navigating using this map and a compass. Many north arrows on maps aren’t telling you anything you actually need to know, or don’t already know. They’re just in the way.

Of course, worse than having a needless north arrow is an inaccurate one. Consider the Robinson Projection:

From Wikipedia

Dropping a north arrow onto this map would be misleading, because where north is varies based on where you are on the map. It’s not always straight up — sometimes it’s up and to the left, sometimes up and to the right, sometimes straight up. The angle of north varies on most map projections, including the one above. Far better than a north arrow in this case is to use a graticule — the grid of latitude and longitude lines, which shows a reader how the cardinal directions change across the map. But even this is not mandatory — a graticule, like a north arrow, is only useful if people really need to have some idea as to directions. Certainly this happens from time to time — if you’re teaching kindergartners where the continents are, then they probably need that information. But if you’re showing this to a tenured professor, they probably already know that New Zealand is east of Australia.

And I won’t even get in to the times I’ve seen students put north arrows on maps of the South Pole.

Scale: Again, most maps don’t need a scale, either. Will people reading your map really be comparing sizes or measuring distances?  Probably not. Again, this is partly a matter of your audience’s familiarity with the area depicted, but if I’m reading the map below, I really don’t care how far apart the states are:

Of course, the other issue is that, since all map projections necessarily distort, the scale of a map is different everywhere. Sometimes the changes are small enough that it’s not a problem, but a scale bar on a world map is going to be wrong most everywhere. It’s better to leave it off rather than to mislead.

Legend: Finally, many maps can do without legends. For a prime example, have a look again at a map I tackled last year:

The legend on this map is completely pointless. Better to write “Cairanne” next to the big red dot in France and trust that readers will figure it out. Map literacy is much like verbal literacy — people learn certain conventions, and we can rely upon most adult audiences to know these. We know that the red dots are cities, and that the words next to them are the city names. No one needs to tell us that at this age. It’s just a waste of our time and space, and potentially confusing (one can wonder if Cairanne is actually a city out in the Mediterranean). Legends aren’t needed to explain every little tiny symbol; just the ones that your audience won’t know.

As with everything that goes onto a map, conscious thought has to go into application of map elements. They should not be rote, or random. They should be employed with consideration of the map’s purpose and audience. That’s what design is — consciousness. It is misleading to say that legends or scales or other map elements are mandatory, and such statements will only lead to more bad maps. We must teach thoughtfulness and sound judgment, not obedience.

I’ve decided to consolidate the Worldwide Campaign to Eliminate Needless North Arrows and the International Crusade Against Useless Scale Bars into the Global Consortium for the Thoughtful Employment of Map Elements (GCTEME). If you would like to join, send a self-addressed, stamped envelope to the following address:

Daniel Huffman
c/o: University of Wisconsin Cartography Lab
550 North Park St.
Madison, WI 53706

I will send you back a letter of membership that looks very official and which will win you respect at NACIS. There are no membership requirements, nor are there actually any benefits. Or activities to speak of, except telling your friends about it.


A Village Floating off the Coast

Today’s contribution comes from my friend Kate, the one with whom I was recently on a Michigan wine tour. This is a map which heads an article on the village of Cairanne and the wines which originate there:

Copyrighted by Click to visit site.

There seems to be some sort of notion out there that every map needs a legend. That, somehow, it’s not a map anymore if it doesn’t have one. This is patently untrue. If you know your audience can easily figure out how to read your symbols, you can probably skip it (or, at least, minimize it). Legends are for imparting literacy when your think audience lacks it. They are frequently needed, but not indispensable.

The legend on this map is clearly dispensable. I cannot fathom why the name of the village was not labeled right next to the giant red dot. Instead, the artist created a legend at the bottom to explain what the giant red dot means. His or her choices suggest the following assumptions were being made about audience:

  • Readers have the skills to figure out that Paris, Dijon, etc. are at the locations of the dots found near those words.
  • Those same readers would not understand what it meant if the word “Cairanne” were similarly placed next to a big red dot in France.
  • But they will, however, know what it means if the word “Cairanne” is placed next to a big red dot outside of France.
  • Readers will know that the big red dot outside France is meant to represent the big red dot inside France.

Some of these assumptions are more questionable than others, to put it mildly. In fact, because of the nonsensical nature of assumption number two, the legend makes this map harder to read. As Kate writes, this map had her “confused for almost a minute about whether they thought Cairanne was in Spain.” Probably because she assumed that the artist would label the big red dot in France as “Cairanne” if it were Cairanne. She was confused because she didn’t think that the map artist might have considered her too dumb to figure it out without a legend.

While we are on the giant red dot, I might strongly recommend making it not so giant. Cairanne is a small village. But the dot pattern on the map gives a subtle impression that Cairanne is huge and Paris is insignificant. The artist wants Cairanne to stand out, understandably. But there are better ways to establish a visual hierarchy on this map, for example by changing the colors of the non-Cairanne cities and dots to fade a little more into the background, and making the Cairanne dot the same size as (or only slightly larger than) the non-Cairanne dots, while still keeping it red so that it pops out.

Meanwhile, making its long-awaited return to this blog, it looks like we’ve got another great example of the Island Effect going on here! Just north of France is some water, indicated in white. Just east of France is some land, indicated in white. Thus, France looks like it’s floating off in the sea, lacking any geographic context. Now, I don’t think this is always a problem — it’s perfectly fine to have a map that shows France and nothing else at times. Here, however, the author is very inconsistent in his or her treatment of geographic context. It seems senseless to show some bits of contextual information (the names of some countries) and leave off others (a little bit of land showing where those countries are). It’s also strange to mark Italy, Spain, and Belgium, while leaving Luxembourg, Germany, and Switzerland off the map. Either France’s surroundings are important, or they’re not. To my mind, it should either be an island and the sole thing on the map, or it should be shown in its full European context with all its neighbors. Going halfway just looks sloppy.

Finally, it’s worth noting that the copyright for this map is placed in a bit of an odd position. It’s between the map and the legend, very much visually in the way. I appreciate the owners of the work wanting to ensure they’re credited, but it could be put less obtrusively in the corner.

One Nice Thing: At least the artist thought to include some geographic context. I can imagine a lot of places would just throw an outline of France on the page, with a dot for Cairanne and nothing else. For people familiar with Paris, Bordeaux, etc., this map helps to give them reference points.

Not every map needs a legend. Nor does every map need several of the other common map elements, for that matter. If I scrounge up a few good examples, I may write a post to kick off my Worldwide Campaign to Eliminate Needless North Arrows, and my International Crusade Against Useless Scale Bars.