University of Twente Student Theses


Evaluation of focus + context techniques applied to network data visualizations

Shadaram, Shahab (2010) Evaluation of focus + context techniques applied to network data visualizations.

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Abstract:Visualizing network data at different spatial scales is a vital need in today‟s applications such as transport planning or traffic management. Sometimes, it is difficult for map readers to explore network data visualizations with large amount of data. Generalization can be used to abstract a network data representation by different activities such as aggregation, but it leads to reduction of some necessary information. Zooming methods like conventional zooming try to provide different zoom levels for map users in order to explore network data visualization at different spatial scales, usually without any reduction or elimination in the network data representation. The problem with conventional zooming is that by zooming in, the context will be lost and overview is not visible anymore and by zooming out, users may get lost in the large amount of data. Focus + context techniques tackle this problem by providing both focus and context area at the same time and make navigation easier than conventional zooming for users. In this research, it is tried to evaluate three focus + context methods, applied on both static and animated network data visualizations. These methods are location map, magnifying glass and fisheye view. Besides providing focus and context at the same time, dynamic characteristics of these methods are other advantages which enable to move the focus area based on user‟s area of interest while maintaining the context. It is assumed that fisheye view is a proper method to apply on static network data visualization due to providing a smooth distortion from the focus to the context area, while it makes the focus area blurred in case of animated network data visualization, magnifying glass has constant magnification that leads to a clear representation of the focus area while it has problems in maintaining the connectivity of lines at the edge of the glass and location map is a proper method to apply on both static and animated network data visualization. These hypotheses are tested in usability test to see if they are correct or not. Enschede road network data is used as a case. Also, speed profiles of vehicles are included in an animated flow line map. After applying focus + context methods on the static and animated network data visualizations, a usability test is held to evaluate the usability (efficiency, effectiveness and satisfaction) of the applied methods. 21 PhD students of ITC participated in the test and the results showed that some improvements need to be developed in the applied techniques, such as increasing the size of the enlarged area and providing different zoom levels for the magnifying glass and fisheye view methods. Most of the participants found location map as the most effective and fisheye view as the most efficient methods. 72% of participants found the location map technique more satisfying than the fisheye view and the magnifying glass techniques, because it provides different zoom levels for them. It is also concluded that the fisheye view technique is not such a useful method to apply on animated road network data visualization. Finally, some recommendations are mentioned for next researchers to consider as future work.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
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