(This is NOT the blog I had planned next for the series, but it is one that may help clarify why this topic is of such significance. If you were not wild about the last blog, you might skip this one.)
In a comment on my last blog regarding cartographic knowledge, Pat McDevitt, VP of Engineering at AOL, formerly with MapQuest, TomTom and Tele Atlas, mentioned his interest in “map-like-graphics”, such as subway maps (see my response to his comment for more detail). In the 1980s, Barbara Bartz Petchenik coined a term for such displays by naming them “map-like-objects”, or MLOs. MLOs sacrifice some aspect of cartographic accuracy to promote easier understanding and use by a selected population. Let’s explore this concept a bit, as a discussion may help to further illustrate the points I was making in my last blog.
The class of MLOs that represent subway maps includes purpose-built graphics designed to help riders of these transportation systems understand how rail lines connect stations in a manner that can be used to plan journeys. Since the rider only can access and exit the trains at specific stops, the actual geometry of the network ( in terms of distance and direction) is of inferior importance to creating a display that is readable, interpretable and actionable in a manner that allows the user to ride between an origin and an intended destination. The argument here is that while MLOs may sacrifice cartographic accuracy, they are tools that can be more effective than using an accurate, detailed map of the same spatial objects. If only the use-case were so simple! Let’s explore by personal example.
I have visited London at least 20 times during the course of my adult life. I usually explore the city riding the London Underground to travel to a location near my planned destination. I admit, with some shame, that of all the urban geographies I have explored I know London’s geography the least well. I find this curious since this location is one of my favorite travel destinations. It is, also, a destination I have visited more frequently than other urban areas that I seem to be able to navigate with little problem.
During my visits to London I was bothered that the objective reality I gained while walking its streets seemed to conflict with where I expected the city’s spatial features to be located. While I was certain that some time/space perturbation was afoot, I was not sure if popping out of the Underground’s “wormholes/tube stations” so distorted my mental map of London that it could not be remediated.
More recently I started exploring the notion that my ill-conceived geography of London actually was a result of traveling using the Underground. I realized, after some consideration of the issue, that my “relative mental spatial reference” for the locations of features of interest in London was likely based on where the nearest tube station was positioned. What is problematic here is that my sense of the geography of the tube stations was informed by the Tube map. Was it really possible that I had used my knowledge of where stations were shown on the ubiquitous Tube map to inform the reality of my above ground wanderings on my probable location? Sounds like science fiction, but could it be true?
To that point, my irrational view of London’s geography might be because the Tube map includes a variety of planned misrepresentations, which you can read about in the article What does London’s Tube Map Really Look Like? Of additional relevance is a study from 2011 by Zhan Guo called Mind the Map (a parody on Mind the Gap – signage familiar to all who have ridden the Tube). Gou concluded that 30 percent of passenger take longer routes because the Tube map misrepresents distances between stations. (You can read a concise version of Gou’s report in the Daily Mail.)
Based on this brief diversion we might conclude that while MLOs can be useful, they may be extremely misleading. Many would say that the problems generated by MLOs result from the users of these maps employing them for purposes for which they were not intended. If that is so, maybe these map-like-objects should come with a use warning, like those on the mirrors of some American cars – perhaps something like:
This map probably represents a spatial area that is considerably larger than this paper/display screen. True distances, directions and spatial context are not represented correctly or reliably. Reliance on this map for any use, even riding the Tube, is not recommended and may result in serious injury, lost time, exposure to buskers, or other inconveniences. The publisher and producer of this map and related licensees are not responsible for errors of omission, commission, or other misrepresentations resulting from lack of cartographic knowledge, incompetency, lack of moral fortitude regarding international border disputes, editorial policies, advertorial policies or, more commonly, frequent cost avoidance cutbacks in map compilation efforts.
While such warning might sound humorous (hopefully), the multiple use issue is of considerable concern. While those who create MLOs may realize the shortcomings of this type of spatial display, I am not sure this type of knowledge is known by users of the map. It is likely that a large proportion of the population that use MLOs will be unaware of the limitations that complicate extending the use environment that the original MLO was designed to allow. In some ways the problem is similar to that experienced by the twenty-six percent of U.S. citizens who, having observed the sky (or not) concluded that the sun revolves around the earth!
The problem of representing spatial reality in maps is extremely difficult. People who use maps do so in one of several manners, but all of these uses involve, to some extent, answering the question “where?” In many cases map use is data driven, prompting people to browse the map in a manner that helps them organize it into a familiar/understandable patterns.
To illustrate this case, imagine that you are viewing an election map displaying states that voted Republican (colored red) or Democrat (colored blue). Most people would explore this display by examining their home state, comparing other nearby states and then looking for the states that voted their preference, followed by those that supported the opposite side. The recollection that most people would have of this map is the patterns made by red and blue states and their spatial clustering across the extent of the map. Even the most cursory inspection of a map usually results in the acquisition of a pattern that is matched with other map patterns that users have acquired. The unfortunate complication here is that users do not know when they are observing an MLO that works well only for a selected purpose, or when they are observing a cartographic display that has been tightly controlled to produce a spatially accurate a representation of the variable being mapped.
Perhaps more pernicious is the hybrid MLO. The American Airlines map that I showed last time was designed to function as an MLO, but was based on a highly accurate cartographic display. In addition, the map was created by a production system that was designed to produce both reference and detailed street maps, but apparently not to produce advertisements or MLOs. Imagine teasing the cartographic reality out of that map. Someone who had not seen a world map before might assume that the globe really does look like what was shown in that display. Well, so what?
I recently read an interesting article by Henry Petroski titled “Impossible Points, Erroneous Walks,” (American Scientist March-April 2014 Volume 102, Number 2, available only by subscription) that was brought to my attention by Dr. Duane Marble shortly after I published my last blog. Petroski, a noted author (he is both a Professor of Civil Engineering and History at Duke University), was railing about an illustration in the New York Times that incorrectly represented the scallops on a sharpened pencil. His thoughts on the seriousness on this seemingly modest error were equally true of MLOs. He wrote:
Books, newspapers, and magazines are also teachers, as are television and radio and the web, as well as the inescapable advertisements. Whether or not we are consciously aware of it, the whole of our everyday experience is an ongoing teaching event.
This is why it is important that what we and our children are exposed to in the broader culture be presented and represented accurately. The words and images that we encounter in common spaces can be no less influential in shaping our perception of the world than what we learn in a formal classroom setting. If we find ourselves surrounded by incorrect depictions of objects, our sense of how things look and work can become so skewed that we lose some of our sense of reality.
This is not to say that there is no room for imagination and creativity in both engineering and artistic work. But even the most abstract of ideas and renderings of them should follow rules of geometry grammar and aesthetics that make them meaningful to venture capitalist and museum-goers alike.” (Petroski, 2014, P1-2 Impossible Walks, Erroneous Points).
There we have it. In the context of maps, we might substitute “But even the most abstract of spatial ideas and rendering them should follow the rules of cartography, map grammar and the design of displays representing spatial distributions…” That of course would return us to the title of my last blog, which was “Does Anyone Need to Know Anything About Maps Anymore?” Of course they should! Next time, let’s resume why this lack of cartographic insight will become a greater problem in the future of online mapping.
Thanks for visiting,