Introduction

As the primary metaphor for computer use shifts from an extension of the personal desktop to a gateway into a vast information space, representing this expanse of information on our relatively small screens becomes increasingly problematic. This discrepancy between display space and information space has been associated with problems in navigation, interpretation and recognition [4]. Our response, distortion based techniques, generally create a multi-scale view that makes chosen sections of the information display more readable by magnifying them while simultaneously adjusting the relative positioning of adjacent sections so as not to cause congestion and/or overlap (for surveys see [4, 6, 7]).

Considerable effort has been put into creating viewing methods appropriate for the information displayed. For each method, a view results from the combination of several different distortion components, creating visual displays that vary considerably. To allow for a fresh perspective on a this problem we identify the distinct aspects that comprise the distortion paradigm. Identifying these components and understanding their effects provides a basis for developing new techniques and for more readily tailoring existing techniques to a given type of data or information application.

Figure 1. Left to right: orthogonal magnification and displacement; orthogonal displacement only, radial displacement only; step magnification; sections of uniform displacement
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Distinctions

• Adjustment/Creation. Distortion viewing techniques are most frequently used to adjust an existing display, however, they can be used to create a layout [3].
• Magnification/Displacement. Traditionally magnification and displacement are used in combination [5] to create magnified foci in context. Displacement alone can provide layout adjustment (Figure1, images 2, 3, 5; Figure 2, images 4, 5).
• Orthogonal/Radial. This distinction has been discussed in terms of our mental map [6] and information appropriate layouts [8] (Figure 1, orthogonal 1, 2, 5; radial 3, 4).
• Euclidean/Structural. Distortion implies that manipulation needs to be applied with a notion of space or type of distance metric. Euclidean distance requires a spatial layout, while a structural distance, such as path length or depth in a hierarchy, does not.
• Expansion/Contraction. When applying displacement separately from magnification one can still consider choices between expansion or contraction.
• Uniform/Non-Uniform. Changes in scale can be uniform for a given section or varying in scale throughout the section [5].
• Linear/Non-Linear Distortions. This distinction is discussed in [5] as a constant or varying rate of change within a section of non-uniform magnification.
• Disjoint/Piecewise-Continuous/Continuous Distortions. Composite functions can be used to provide the distortion, and can be combined in a step, piecewise, or continuous manner.
• Global/Excluded. Most distortion techniques are global, affecting the entire display. One application of exclusion is to keep focal areas clear of distortion [1] (Figure 2; 1, 2).
• Global/Constrained. Similarly to the idea of excluding sections from the distortion, a distortion technique can be constrained to a local area [1] (Figure 2; 1, 3).
• Information or Data Aspects. These techniques can be applied to a subsection of the data or information display, for example, either the nodes or edges of a graph (Figure 2, right).
• Distortion Dimensionality. A distortion can be thought of as having a dimensionality. It can be applied in any or all of the three display dimensions.
• Distortion Alignment. The distortion can be aligned with respect to the data, the data's layout, the display space or user's viewpoint.

Figure 2. Left three; distortion variations: Right two; local displacement expands node cluster.
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References

[1] Carpendale, M. S. T., Cowperthwaite, D. J., and Fracchia, F. D., 3-Dimensional Pliable Surfaces: For effective presentation of visual information. ACM UIST, 1995 217-226.

[2] Carpendale, M. S. T., Cowperthwaite, D. J., Storey, M-A.D., and Fraccia, F. D., Exploring Distinct Aspects of the Distortion Viewing Paradigm. Technical Report TR 97-08, School of Computing Science, Simon Fraser University, March 1997.

[3] Henry, T., and Hudson, S., Interactive Graph Layout., ACM UISIT, 1991, 55-64.

[4] Leung, Y. K., and Apperley, M. D., A Review and Taxonomy of Distortion-Oriented Presentation Techniques. ACM ToCHI, 1(2), 1994, 126-160.

[5] Misue, K., Eades, P., Lai, W., and Sugiyama, K., Layout adjustment and the mental map. Technical report IIAS-RR-94-1E Fujitsu Laboratories, 1994.

[6] Noik, E. G., A Space of Presentation Emphasis Techniques for Visualizing Graphs. Graphics Interface, 1994, 225-233.

[7] Spence, R., A taxonomy of Graphical Presentation., Information Engineering Section report 93/3, Imperial College of Science, Technology and Medicine, 1993.

[8] Storey, M-A. D., and Müller, H. A., Graph layout adjustment strategies. Graphing Drawing, 1995, 487-499.

Posters Presentation

Visualization For Structural Biology by Ioan M. Boir Martin and Dan C. Marinescu

Distinct Aspects of the Distortion Viewing Paradigm by M. S. T. Carpendale, D. J. Cowperthwaite, M-A. D. Storey, F. D. Fracchia, and A. Liestman

Extending Table Lens to Multidimensional Data and OLAP Operations by Ramana Rao and Tichomir Tenev

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