“And what exactly is it you’re trying to tell me?” History of the Union Army @ HistoryShots: http://www.historyshots.com/Union/index.cfm

As part of my recent “assessment obsession,” I’m now researching strategies for critiquing maps. Each week, students in my Urban Media Archaeology class will be reviewing a selection of maps and assessing what they illuminate and obfuscate, how they integrate form and content effectively and poorly, whether or not they serve their intended purpose, and what lessons we can take away from them and apply, or avoid, in our own mapping projects. Here’s my preliminary round-up of map critique resources; we’ll have to work together to distill all of this into some kind of flexible rubric — one that applies to maps as multimodal media (which is not how most of these folks seem to conceive of maps).

Harvard GSD, “Elements of Cartographic Style“:

  • Must consider difference between topographic and thematic maps

All maps should contain:

  • Title
  • Name / Institutional Affiliation / Date
  • Caption: “explains the critical concepts and relationships you are trying to illustrate”
  • Labeled Key Elements
  • Citations and dates for primary sources of data
  • Citation of projection method and case
  • Graphical Scalebar
  • Graphical Hierarchy: “key concepts as discussed in the caption should be given emphasis with a bright color and bold lineweights and labels. Key relationships may be portrayed with diagrammatic graphics”
  • Concise Legend, if Necessary

Advice for Thematic Maps: “The map is not the territory… Just so your map readers know that you are not confusing data with a perfect representation of reality your discussion of a thematic map should begin with a description of what the data literally represent — observations of particular classes of entities made for a specific purpose at a particular time, with a particular precision and aggregate units. After this explanation, you can go on to make statements about how the data do or do not adequately represent the concepts of interest for your study.”

Elements that every thematic map should have:

  • “Contextual Framework Portraying data without a contextual reference overlay as discussed in the sections on topographic mapping is pointless.
  • Concise, evocative legend Your thematic data should be re-categorized if necessary so that your readers are not challenged to keep track of more than 5 different classes. Seven, maximum.
  • Use plain terms in legend headings and labels If you accept the software defaults for your legend labels and headings, people who understand maps will also understand that you simply don’t care about communicating.
  • Try not to hide important information in arbitrarily broad categories The categories portrayed in the legend, whether qualitative or quantitative, should highlight distinctions that are useful.
  • Discuss the Aerial Precision of Mapping Units Whether the data are quantitative or qualitative, thematic data have a particular granularity. For example Census Data may be aggregated at a Block level or Tract. Land Use Data may only register distinctions for patches of ground larger than a stated Minimum Mapping Unit (like 5 acres, or a 90 meter cell.)
  • Graphical Hierarchy the same ideas about graphical hierarchy that apply to topographic maps may also apply with thematic maps. This is especially true with regard to the foreground layer of key topographic features and a reference layers to provide context. You may decide to drop some of the labels used in your reference layer — particularly when your map document includes separate maps for presenting the contextual framework. Typically, the thematic layer will be the background layer of the map but you may also use transparency and an aerial photo at large scales, or shaded relief at smaller (broader) scales. When mixing background layers with transparency you should be careful that whatever background layers you use — particularly aerial photos and or shaded relief, to not make the key distinctions in your thematic layer more difficult to read.”

Adrienne Gruver, “Visual Thinking and Visual Communication” Lesson in Geography 486: “Cartography and Visualization,” Penn State:

  1. Subject
  2. Purpose
  3. Audience
  4. Data Variables Shown
  5. Visual variables used to represent or symbolize the data variables (e.g. hue, size)
  6. Is there a logical match between the kind of data variable shown and the kind of visual variable used to represent it?
  7. Appropriate map specifications, e.g. color, size, output file, etc depending on how the map should be read/used (print, web etc).
  8. What is confusing or takes time to understand?
  9. What is well-done vs. what could be improved?
  10. How does design contribute to all of the above?

We need to extend these variables so that they encompass multimodal maps — i.e., maps that aren’t purely visual.

Denis Wood & John Fels, The Natures of Maps: Cartographic Constructions of the Natural World (Chicago: University of Chicago Press, 2008):

From Robert Karrow, Jr.’s, review, in Technology and Culture (October 2009):

“In terms of methodology, Wood and Fels rely, first, on extremely thorough and systematic “unpacking” of the map, the kind of analysis they famously directed at a North Carolina state highway map in The Power of Maps. And to assist in this process, they’ve adapted some terms from literary analysis that allow them to talk about a map’s context. They speak of the parimap as the verbal and physical expressions that surround and embody the map, everything from titles and legends to paper stock and typography. They also recognize an epimap, constituting information not physically a part of the map, but circulating freely around it. Elements of an epimap would include advertising, commentary, and packaging, like the issue of National Geographic that holds a given map. Together, parimap and epimap constitute the paramap, “everything that surrounds and extends a map in order to present it.”

Climate Cartographics“:

Guidelines for critiquing maps, drawing on Wood & Fels:

1. Layout and Perimap: How do the title, captions, text color, balance and other elements of the perimap set the context for reading the map?

2. Data Presentation: What symbology, colors, background, projection and other features in the map image contribute the map’s message?

3. Data Analysis: What type of data is shown? What are the classification techniques, choice of scale, research methods, and sources?

4. Message: What is the message of the map? How effectively is it communicated? Who is the intended audience?

5. Recommendations: How should the map be changed so that it would communicate the message more effectively?Xx

From James Corner’s “The Agency of Mapping: Speculation, Critique and Invention” In Denis Cosgrove, Ed., Mappings:

  • Consider “what is selected and prioritized…, what is subsequently left aside or ignored, how the chosen material is schematized, indexed and framed, and how the synthesis of the graphic field invoked semantic, symbolic, and instrumental content” (216)
  • Consider “the graphic system within which the [map’s] extracts will…be organized. The system includes the frame, orientation, coordinates, scale, units of measure and the graphic projection (oblique, zenithal, isometric, anamorphic, folded, etc.). The design and set-up of the field is perhaps one of the most creative acts in mapping.” (229)
  • Consider the essential operations in mapping: “first, the creation of a field, the setting of rules and the establishment of a system; second, the extraction, isolation or ‘de-territorialization’ of parts and data; and third, the plotting, the drawing-out, the setting-up of relationships, or the ‘re-territorialization’ of the parts. At each stage, choices and judgments are made, with the construing and constructing of the map alternating between processes of accumulation, disassembly and reassembly” (231)

Other Resources:

**Judy M. Olson, “Multimedia in Geography: Good, Bad, Ugly, or Cool?” Annals of the Association of American Geographers 87:4 (December 1997): 571-578.

Cynthia Brewer, Designing Better Maps: A Guide for GIS Users (ESRI Press, 2005).

Vidya Setlur, Cynthia Kuo, Peter Mikelsons, “Towards Designing Better Map Interfaces for the Mobile: Experiences from Example” COM.geo 2010.

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