Polyfocal display

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Polyfocal display is an interactive technique that allows to selectively zoom in to a section of an image. Scaling is described by a (two–dimensional) magnification function, providing for generating several foci — each having induvidual magnification–parameters and correspondingly adjustable distortion in the regions further away from the focus.
The Polyfocal Display function defines an area for a focal point as a location of high radial magnification accentuated by a surrounding area of decreased magnification. Two parameters define the level of distortion found in the resulting transformation. The first parameter controls the level of magnification at the focal point, whereas the second one controls the rate of change of magnification with distance from the point of focus (Leong). Multifocal polyfocal displays also exist, in which more than one focal point is specified.
[Gerstmann, 2001]

Magnification function

Polyfocal display was proposed by Naftali Kadmon and Eli Shlomi for presentation of statistical data on cartographic maps.


  • [Gerstmann, 2001]: Derek Gerstmann, Advanced Visual Interfaces for Hierarchical Structures, 2004