Visual Variables: Difference between revisions
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Marks can be | Marks can be | ||
* Points | * '''Points''' are dimensionless locations on the plane, represented by signs that obviously need to have some size, shape or color for visualisation. | ||
* '''Lines''' represent information with a certain length, but no area and therefore no width. Again lines are visualised by signs of some thickness. | |||
* Lines | * '''Areas''' hava a length and a width and therfore a two-dimensional size. | ||
* '''Surfaces''' are areas in a three-dimensional space, but with no thickness. | |||
* Areas | * '''Volumes''' have a length, a width and a depth. They are thus truly three-dimensional. | ||
* Surfaces | |||
* Volumes | |||
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=== Characteristics === | === Characteristics === | ||
The choice of the variable, which would be most appropriate to present each aspect of information depends on the | The choice of the variable, which would be most appropriate to present each aspect of information depends on the characteristics. | ||
* Selective | * '''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. | ||
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 across changes in other visual variables. | ||
* Associative | * '''Quantitative:''' If the difference between two marks in this variable can be interpreted numerically, the visual variable is quantitative. | ||
Several marks can be grouped | * '''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. | ||
* Quantitative | * '''Length:''' The length defines how many values the variable features. For example how many shades of grey can be recognised. | ||
If the | |||
* 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 == | == References == | ||
Revision as of 17:47, 30 October 2006
Information may not have a direct visual manifestation. Therefore one needs to map this information to a visual representation. This is done by visual varibles.
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 are dimensionless locations on the plane, represented by signs that obviously need to have some size, shape or color for visualisation.
- Lines represent information with a certain length, but no area and therefore no width. Again lines are visualised by signs of some thickness.
- Areas hava a length and a width and therfore a two-dimensional size.
- Surfaces are areas in a three-dimensional space, but with no thickness.
- Volumes have a length, a width and a depth. They are thus truly three-dimensional.
Visual Variables
Jaques Bertin defined seven Visual Variables [Bertin, 1967] consisting of:
Since nowadays information is presented by computers, the addition of motion as a new visual variable becomes important.
Characteristics
The choice of the variable, which would be most appropriate to present each aspect of information depends on the characteristics.
- 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 across changes in other visual variables.
- Quantitative: If the difference between two marks in this variable can be interpreted numerically, 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