Symbolizing: Basic Design Principles

Graphic elements, controls and components

Objectives of lecture:

1. Reminder to those who missed EVENT 04 on Monday to pick up answer sheet and submit a makeup
2. Acknowledge some glorious maps (on paper and digital). Keep up the good work!
3. Start with a Pictionary non-event
4. Introduction of Graphic Elements and basic design principles

Goal: present geographic information using graphic media in such a manner to communicate the message effectively and efficiently.

The Model: Robinson, and coauthors describe map design as an interaction:

graphic elements are the visual variables which can be manipulated to achieve the components (of design) within the bounds of the controls (technical constraints).

This is a paraphrase of Bertin's Semiologie Graphique 1968, English translation not published until 1983. Dent has part of it, MacEachern develops it further. See course bibliography.

Primary Graphic Elements

("Symbol dimensions" in Dent)

• Size dimensions of graphic symbols (diameter, area, width, height...). Communicates magnitude (maybe order).
• Shape distinct visual recognition based on regular/irregular, smoothness/ sharpness and other geometric characteristics. Communicates nominal categories.
• Hue commonly called "color", the spectral variations perceived by the human visual system as categories (eg. red, green, blue, cyan, magenta, yellow). Communicates nominal categories
• Value relative lightness or darkness. Communicates order or magnitude.
• Saturation (sometimes called Intensity or Chroma) gradation from grey to intense hue at same level of value (dark/light). Communicates order.
• Spacing distance of marks in symbols (# lines per inch, dots/inch...) [when spacing is close and objects are small, readers perceive value, not spacing]. (Dent calls this pattern texture.) Communicates nominal distinctions unless the user perceives it as value.
• Orientation directional arrangement of elongated individual marks. oriented to frame of reference, but can be affected by geometry of cartographic objects. (Dent calls this pattern orientation with a separate dimension of pattern arrangement.) Communicates nominal distinctions.
• Location position in the visual field of reference. constrained by geographic facts.

Recent lists have added a graphic element:

• Focus: sharpness of definition of objects; a degree of blurriness could communicate an ordering (or quantitative scale) [perhaps most useful for uncertainty in locating the object?]

Graphic Components

Five Controls of graphic design:

The graphic variables have a natural association with

points/lines/areas

and they have an even closer connection to

levels of measurement.

A style of mapping is a formula for combining graphic variables to achieve certain goals under the constraints (objective, audience, "reality", scale etc.).

There are lots of attempts to prescribe the correspondence between levels of measurement and graphic elements. Dent has a simple version in Table 4.4 page 77, with more detail (borrowed from Muehrcke in Figure 4.6 and 4.7 page 78) These give a rough idea, but there are exceptions and special cases to consider. MacEachern has a more complete matrix, with all kinds of issues raised...