Visual Variables: Difference between revisions
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== | == Definition == | ||
=== Marks === | |||
== Marks == | |||
A mark is made to represent some information other than itself. It is also referred to as a sign. | A mark is made to represent some information other than itself. It is also referred to as a sign. | ||
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== Characteristics == | === Visual Variables === | ||
Jaques Bertin defined seven '''Visual Variables''' [Bertin, 1967] consisting of: | |||
[[Image:visualVariables.png]] | |||
* 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. | The choice of the variable, which would be most appropriate to present each aspect of information depends on the caracteristics. | ||
Revision as of 17:37, 30 October 2006
Definition
Marks
A mark is made to represent some information other than itself. It is also referred to as a sign.
Marks can be
- Points
Points are dimensionless locations on the plane, represented by signs that obviously need to have some size, shape or color.
- Lines
Lines represent information with a certain length, but no area and therefore no width. Again lines are visualised by signs of some thickness.
- Areas
An area has a length and a width and therfore a two-dimensional size.
- Surfaces
Surfaces are areas in a three-dimensional space, but with no thickness.
- Volumes
A volume has a length, a width and a depth. It is thus truly three-dimensional.
Visual Variables
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