Halo (visualization technique)
- For other uses, see Halo (disambiguation).
In information visualization, the halo technique is a method for viewing large documents on small screens or display windows, which functions by pointing users to the locations objects out of the visible field. Off-screen objects are surrounded by rings which reach into the border visible field (or window). From the position of the arc-shaped marker, combined with its curvature, users can infer the off-screen location of the object.
Halo has been used to display maps on personal digital assistants and mobile phones. The name of the technique was derived from the metaphor of a streetlamp shining a halo onto the street. The technique was invented by Patrick Baudisch in 2001, while at Xerox PARC,
A similar concept is arrow location, where the direction of objects is represented by a directional marker shown in the border. This variant has been used in 3D video games for several years. Arrow-based techniques convey the direction to off-screen locations, but require additional scale-dependent annotations in order to convey distance. Halo arcs, in contrast, point to a location, which implies direction and distance.
Advantages
- Faster and more reliable comprehension than techniques based on arrows.
- Halo is scale-independent, because arcs point to a location, rather than indicate a (scale-dependent) distance.
- Application designers can use arc color, thickness and texture to convey additional parameters, such as type of off-screen location or desirability.
Disadvantages
- More prone to clutter than arrow-based techniques
- Notion of distance decreases for objects located far away