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ZVTM provides full support for Sigma Lenses, which are instantiated and programmatically manipulated in the same manner as distortion lenses described hereafter. See the Lens package API documentation for more information. The CHI 2008 paper gives the theoretical background behind Sigma lenses. it is available from the ACM Digital Library or the HAL-INRIA open archive. The companion video is available as a Quicktime movie, and on YouTube.

screenshots of various sigma lenses


Magnification lenses make it possible to create focus + context representations. They can be associated with any ZVTM external standard view (they cannot yet be associated with accelerated views). The following demo shows a distortion lens (a.k.a graphical fisheye lens). There are many other types of magnification lenses available in ZVTM, including all Sigma Lenses.

Drag the mouse (left or right button) to pan. Hold shift and drag the mouse vertically to zoom in/out.

Note: depending on your browser and Java plug-in, a bug might prevent the lens from appearing the first time you activate it. Just drag the mouse inside the applet to make the lens appear. The problem disappears for subsequent lens (de-)activations.


See Section 5.2 of the Developer's guide.