Five Common Map Afflictions, Causes, and Solutions

(1) Map Measles: Too many points at too low of a zoom level. Caused by lack of zoom-level specific coding and/or lack of simplification pre-processing. The solution is to pre-process the data to rid it of the least important points, or to on-the-fly select by attribute (e.g., “population > 500,000”), or on-the-fly binning (e.g., hexagonal binning). Rx: TileMill’s Styling For Zoom Levels tutorial, Hexbin discussion on indiemaps.

(2) Blotchy Skin: Jarring colors interrupt an otherwise flawless complexion. Caused by lack of pre-determined color palette. The solution is to choose a color palette prior to beginning the project and adjust it as needed. Rx: Color Brewer, Cartographer’s Toolkit, Colour Lovers, your own art collection.

(3) Abnormal Cell Walls: Differentiation of polygonal features via varying polygon line-widths and colors, cataclysmically colliding at shared boundaries. Caused by rapid output needs and resulting sloppiness. The solution is to use inner-buffering to provide a continuous color for each polygon while allowing for neighboring polygons to have a different color. Rx: view how it’s done, buffer with QGIS using negative distance.

(4) ADHD: No clear hierarchy of elements, features jumbled in an inappropriate order. Caused by misuse or ignorance of established standards. Also caused by human error and not acquiring critical feedback from outside sources prior to publication. The solution is to be aware of appropriate layer order (e.g., state borders under interstates, park shading under local roads). Rx: study Google Maps, seek critique.

(5) Over Accessorizing: Putting everything on the map that can be put on the map. Caused by GIS analysts, who have a multitude of information at their fingertips, wanting to squeeze every potential drop of wisdom possible out of the data by presenting it all at the same time, resulting in less information transfer rather than more. Also caused by meddling bosses. The solution is to drill down to only the salient details, to separate data into comprehensible segments, to present different maps in different tiles, or to put in a huge effort in getting the data massaged together (e.g., road atlas). Rx: study road atlases, NYTimes map graphics, MIT Senseable City Lab products, winning maps from various map competitions (e.g., NACIS 2012 narrative, first place GISCI 2012).

  1. #1 by John Nelson on April 22, 2013 - 1:56 pm

    I used to think measles maps were bad news, too, until I started making them. If you map enormous volumes of a single subject, the results can show beautiful patterns of a larger phenomenon you never though to investigate. Lots-o-dots can yield lots of insight.

    Humans are really good at detecting structural patterns in a dense population -but we are really bad at differentiating lots of symbol types (your #5).

    Give intentional measles mapping a try and you might have fun; aggregation can be a preemptive bummer. And if you are aggregating by scale to optimize online maps, I feel your pain, but try pre-processing and serving as a raster.

    Anyway, great list, great blog, and thanks for the insights!

  2. #2 by Bill Duffy on April 22, 2013 - 5:20 pm

    I’ve always called #5 the Pizza Special – one map with everything on it. A constant battle with my clients.

  3. #3 by Holly Glaser on April 25, 2013 - 4:15 pm

    I object to your use of ‘ADHD’ in your problem list.
    There are many people who have ADHD and struggle with it every day of their lives. Using ADHD as a joke is just plain insensitive and rude.

    Kindly apologize and rewrite your article to regain my respect

  4. #4 by Gretchen on April 25, 2013 - 7:19 pm

    @Holly: It’s good to point out that real ADHD is a much more serious diagnosis than any one could give to a map.

  5. #5 by Ben on April 29, 2013 - 7:42 am

    This article (and this whole site) is very helpful for a person like me who, while having years of analytic experience, has cartographic skills that leave something to be desired.

    @ Holly: I have severe ADHD and struggle with it every day, but this world needs a little more levity. These days, people are overly sensitive, overly litigious, overly hostile and overly negative in general. ADHD has also given me the desire for many interests and hobbies in life, which keep me busy but in the process have a profound calming effect.

    Great tips, keep them coming.

  6. #6 by Gretchen on April 29, 2013 - 7:34 pm

    @Ben: Glad you’re getting a lot out of the site! Thanks for your input.

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