Maps as abstractions of reality: Benefits and costs
Chapter 1: Context and Concepts

Maps try to display some aspect of reality. But like books, movies, television, or newspapers that try to do the same, they fall short (figure 1.7). The only perfect representation of reality is, after all, reality itself. ("You had to be there.") All else is, to a greater or lesser degree, an abstraction. Abstractions present choices. How much abstraction can we tolerate? How much information can we afford to lose? The fundamental tradeoff is:

  • More abstraction equals less information (farther from reality).

  • Less abstraction equals more information (closer to reality).

The tradeoff can also be viewed this way:

  • More abstraction equals greater simplicity and legibility (more effective visual communication).

  • Less abstraction equals greater complexity, less legibility (less effective visual communication).

    Figure 1.7

    In our quest to represent reality as faithfully as possible, we may be tempted to put too much "stuff" in our maps or other graphics. This may give us maps that have a lot of information but that may be illegible junk heaps. Usually, the abstraction-reality tradeoff should tilt us in the direction of simplicity. Better to have one or two important points clearly understood than to have utter confusion pushing readers toward anger and frustration. Worse yet, that confusion may cause readers to draw incorrect conclusions. That outcome could be worse than no map at all.

    Consideration of this tradeoff should be part of the map production process. With practice, it will become "second nature" and will not need much thought. But for the novice, it is an important issue calling for thought and perhaps discussion with colleagues. Reading Tufte (1983, 1990) will raise awareness.

Chapter 1: Context and Concepts
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Mapping Crime: Principle and Practice, by Keith Harries, Ph.D., December 1999