Teaching:TUW - UE InfoVis WS 2008/09 - Gruppe 01 - Aufgabe 1 - Visual Encoding
Visual Encoding
Definition
Visual encoding is the set of techniques enabling the representation of data on a screen or on paper. It comprises of the use of shapes, colours, areas and other visual variables that make it possible to associate data variables to graphic variables.[Dürsteler] . Visual encodings are mappings of information to display elements.[Munzner]
Techniques of Visual Encoding
The fundamental substrate of visualizations is spatial position. Marks such as points, lines, or area-covering elements can be placed on this substrate. These marks can carry additional information independent of their spatial position, such as size, greyscale luminance (brightness) value, surface texture density, color hue, color saturation, curvature, angle, and shape.[Munzner]
- space
- marks
- connections & enclosures
- retinal properties
- temporal encoding
- viewpoint transformation
space
When you think about an empty paper as the beginning of a visualisation, the space between some possible object is one of the most powerful aspects to give something an important note.
marks
Marks are the visible things that occur in space [Jacko]. You can distinguish between four types of Marks
- Points
- Lines
- Areas
- Volumes
connections & enclosures
Connections and enclosures build the important dependencies between the objects (marks). Connections show a relationship between objects, while enclosures can also indicate related objects.
retinal properties
Retinal properties describe how objects (marks) look like. In other words they are the informations that are carried by marks, such as crispness, shape, resolution, transperancy, color(value,hue&saturation), grayscale.[Munzner]
temporal encoding
It's the encoding which depends on the temporal changes of marks(mark position and their retinal properties).
viewpoint transformations
Viewpoint transformation is the modification of the view position of the viewer, the ability to interactively modify and augment Visual Structures and to turn static presentations into visualizations, thus enhancing the perception.
There are three common view transformations :
- Location Probes : Usage of Location in the visual structures to reveal additional info
- Viewpoint control : Modification of the view position of the viewer against the Visual structure for modifying some viewing parameters to enhance the visual perception. (Moving the viewpoint to create visualisation : Pan,zoom,clip the viewpoint)
- Distortion : Creating a focus area and context area.
References
- [Munzner,2000] Interactive Visualization of Large Graphs and Networks, EN: http://graphics.stanford.edu/papers/munzner_thesis/