Visual Variables

Basic Definiton

Jaques Bertin defined seven Visual Variables [Bertin, 1967] consisting of:

• Position
• Size
• Shape
• Value
• Color
• Orientation
• Texture

Since information is presented by computers, the addition of motion as a new visual variable gets important.

Characteristics

The choice of the variable, which would be most appropriate to present each aspect of information depends on the caracteristics.

• Selective

If a mark changes in this variable and it can be selected by the other marks easily the visual variable is said to be selective.

• Associative

Several marks can be grouped accross changes in other visual variables.

• Quantitative

If the differnce between two marks in this variable can be interpreted numerical, the visual variable is quantitative.

• Order

If the variable supports ordered reading it is an ordered visual variable. This means that a change could be read as more or less. e.g. in size you can order according to the area of the marks.

• Length

The length defines how many values the variable features. For example how many shades of grey can be recognised.

References

• Proceedings

[Bertin, 1967] Bertin, Jaques: "Sémiologie Graphique". Paris: Editions Gauthier-Villars. Deutsche Übersetzung von Jensch, G.; Schade, D.; Scharfe, W.: Graphische Semiologie.Diagramme – Netze - Karten. Berlin: Walter de Gruyter, 1974.

[Skupin, 2000] Skupin, A: "From Metaphor to Method: Cartographic Perspectives on Information Visualization" IEEE Symposium on Information Visualization. October 9-10, 2000, Salt Lake City, Utah.

[Carpendale, 2003] M. S. T. Carpendale: "Considering Visual Variables as a Basis for Information Visualisation", University of Calgary, Department of Computer Science, 2001-693-16, 2003