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First publ. in: Encyclopedia of Database Systems / Ling Liu and M. Tamer Özsu (ed.). Berlin: Springer, 2009, pp. 3684-3689.
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ABSTRACT: Maps are currently the most common application domain for zoomable user interfaces (ZUIs). Standard techniques for controlling such interfaces on pen-operated devices usually rely on sequential interaction, i.e. the users can either zoom or pan. A more advanced technique is speed-dependent automatic zooming (SDAZ), which combines rate-based panning and zooming into a single operation and thus enables concurrent interaction. Yet another navigation strategy is to allow for concurrent, but separate, zooming and panning. However, due to the limitations of stylus input, this feature requires the pen-operated device to be enhanced with additional input dimensions. We propose one unimanual approach based on pen pressure, and one bimanual approach in which users pan the view with the pen while manipulating the scale by tilting the device. In total, we developed four interfaces (standard, SDAZ, pressure, and tilting) and compared them in a usability study with 32 participants. The results show that SDAZ performed well for both simple speed tasks and more complex navigation scenarios, but that the coupled interaction led to much user frustration. In a preference vote, the participants strongly rejected the interface and stated that they found it difficult and irksome to control. This result enhances previous research, which in most cases found a high user preference for SDAZ, but focused solely on simple speed tasks. In contrast, the pressure and tilt interfaces were much appreciated, which, considering the novelty of these approaches, is highly encouraging. However, in solving the test tasks the participants took hardly any advantage of parallel interaction. For a map view of 600×600 pixels, this resulted in task-completion times comparable to those for the standard interface. For a smaller 300×300 pixels view, the standard interface was actually significantly faster than the two novel techniques. This ratio is also reflected in the preference votes. While for the larger 600×600 pixels view the tilt interface was the most popular, the standard interface was rated highest for the 300×300 pixels view. Hence, on a smaller display, precise interaction may have an increased impact on the interface usability. Overall, we believe that the alternative interaction techniques show great potential for further development. In particular, a redesign should encourage parallel interaction more strongly and also provide improved support for precise navigation.
International Journal of Human-Computer Studies.
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Thorsten Büring
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ABSTRACT: Based on a comprehensive review of related work, the reported research is structured in two parts. First, we focus on the development of mobile starfield displays. Starfield displays are complex retrieval interfaces that encode and compress abstract data in a zoomable scatterplot visualization. To better adapt the interface to the requirements of a small screen, we merged the starfield approach with semantic zooming, providing a consistent and fluent transition from overview to detail information inside the scatterplot. While the participants in an informal study gave positive feedback regarding this type of data access, they also showed difficulties in orienting themselves in the information space. We further investigated this issue by implementing a zoomable overview+detail starfield display. Thus, while navigating the detail view, the users could keep track of their current position and scale via an additional overview window. In a controlled experiment with 24 participants, we compared the usability of this approach with a detail-only starfield and found that the separate overview window was not able to improve user satisfaction. Moreover, due to the smaller size of the detail view and the time needed for visual switching, it worsened task-completion times. This result led us to implement a rectangular fisheye view for starfield displays. The interface has the advantage that it displays both detail and context in a single view without requiring visual switching between separate windows. Another usability evaluation with 24 participants was conducted to compare the focus+context solution with an improved detail-only ZUI. While task-completion times were similar between the interfaces, the fisheye was strongly preferred by the users. This result may encourage interface designers to employ distortion strategies when displaying abstract information spaces on small screens. Our research also indicates that zoomable starfield displays provide an elegant and effective solution for data retrieval on devices such as smartphones and PDAs. The second part of the research deals with map-based ZUIs, for which we investigated different approaches for improving the interaction design. Maps are currently the most common application domain for ZUIs. Standard interfaces for controlling such interfaces on pen-operated devices usually rely on sequential interaction, i.e. the users can either zoom or pan. A more advanced technique is speed-dependent automatic zooming (SDAZ), which combines rate-based panning and zooming into a single operation and thus enables concurrent interaction. Yet another navigation strategy is to allow for concurrent, but separate, zooming and panning. However, due to the limitations of stylus input, this feature requires the pen-operated device to be enhanced with additional input dimensions. We propose one unimanual approach based on pen pressure, and one bimanual approach in which users pan the view with the pen while manipulating the scale by tilting the device. In total, we developed four interfaces (standard, SDAZ, pressure, and tilting) and compared them in a usability study with 32 participants. The results show that SDAZ performed well for both simple speed tasks and more complex navigation scenarios, but that the coupled interaction led to much user frustration. In a preference vote, the participants strongly rejected the interface and stated that they found it difficult and irksome to control. In contrast, the novel pressure and tilt interfaces were much appreciated. However, in solving the test tasks the participants took hardly any advantage of parallel interaction. For a map view of 600x600 pixels, this resulted in task-completion times comparable to those for the standard interface. For a smaller 300x300 pixels view, the standard interface was actually significantly faster than the two novel techniques. This ratio is also reflected in the preference votes. While for the larger 600x600 pixels view the tilt interface was the most popular, the standard interface was rated highest for the 300x300 pixels view. Hence, on a smaller display, precise interaction may have an increased impact on the interface usability. Ausgehend von einem umfangreichen Überblick über den bisherigen Forschungsstand, gliedert sich die vorliegende Arbeit in zwei Schwerpunkte. Zunächst wird über die Entwicklung von mobilen Starfield Benutzeroberflächen berichtet. Starfields sind komplexe Suchprogramme, die abstrakte Daten mittels eines Punktdiagramms darstellen und visuell komprimieren. Um diese Benutzeroberflächen besser an die Anforderungen kleiner Bildschirme anzupassen, haben wir Starfields mit einer semantischen Zoomfunktion erweitert. Diese erlaubt einen flüssigen und konsistenten Übergang von Übersichts- zu Detailinformation im Punktdiagramm. Ein entsprechend entwickelter Prototyp stiess in einer informalen Nutzerstudie auf positive Resonanz. Es zeigte sich jedoch auch, dass die Probanden Schwierigkeiten mit der Orientierung im Datenraum hatten. Um diesen Umstand näher zu untersuchen, entwickelten wir eine Overview+Detail Benutzeroberfläche für Starfield Applikationen. Diese erlaubte es den Nutzern während der Navigation in einer Detailansicht, die Position und die Skalierung des momentan sichtbaren Datenausschnitts in einem zusätzlichen Übersichtsfenster abzulesen. In einer Nutzerstudie über Bedienungsqualität mit 24 Teilnehmern verglichen wir den Overview+Detail Ansatz mit einer ursprünglichen Variante der Oberfläche, welche lediglich eine Detailansicht bot. Wir fanden heraus, dass das Übersichtsfenster die Nutzerzufriedenheit nicht steigern konnte. Zudem führte die kleinere Detailansicht und das stetige visuelle Hin- und Herwechseln zwischen den zwei Fenstern zu einer signifikanten Zeiteinbusse bei der Bewältigung von Testaufgaben. Aufgrund dieses Ergebnisses wurde in einem weiteren Projekt eine rechtwinklige Fischaugenverzerrung für Starfields entwickelt. Diese Oberfläche hat den Vorteil, dass Detail- und Kontextinformationen in einer integrierten Ansicht dargestellt werden können, und sich der Benutzer somit während der Navigation auf ein einzelnes Fenster konzentrieren kann. Eine weitere Nutzerstudie mit 24 Probanden wurde durchgeführt, um die Fischaugenverzerrung mit einer weiterentwickelten Variante des semantischen Zooms zu vergleichen. Während es keinen Zeitunterschied bei der Bewältigung der Testaufgaben zwischen den Oberflächen gab, wurde die Fischaugenoberfläche von den Probanden stark präferiert. Dieses Ergebnis ermutigt Designer, in Zukunft verstärkt Verzerrungstechniken für die Visualisierung von abstrakten Daten auf kleinen Bildschirmen einzusetzen. Unsere Forschung deutet auch darauf hin, dass Starfield Applikationen eine elegante und effektive Oberflächenlösung für die mobile Datensuche mit Smartphones und PDAs bieten. Der zweite Teil der Arbeit befasst sich mit kartenbasierten ZUIs, für welche ein verbessertes Interaktionsdesign entwickelt werden soll. Karten sind der momentan häufigste Anwendungsbereich für ZUIs. Der Standardansatz zur Bedienung derartiger Applikationen auf Geräten mit Stifteingabe beruht zumeist auf sequentieller Interaktion, d.h. die Nutzer können entweder Zoomen oder Pannen. Eine demgegenüber fortgeschrittene Technik ist Speed-Dependent Automatic Zooming (SDAZ), welches kontinuierliches Pannen mit Zoomen in eine einzelne Nutzereingabe bündelt und daher eine simultane Navigationsinteraktion ermöglicht. Wiederum ein anderer Ansatz ist es, dem Nutzer eine simultane aber zusätzlich auch separate Kontrolle von Zoomen und Pannen anzubieten. Eine derartige Funktionalität erfordert jedoch, dass die ansonsten zu begrenzte Stifteingabe mit weiteren Eingabedimensionen erweitert wird. Diesbezüglich stellen wir eine einhändig zu bedienende Technik basierend auf Stiftdruck vor, und eine zweihändige Variante, bei der der Nutzer den Kartenausschnitt mit dem Stift horizontal und vertikal navigiert, während die Skalierung der Ansicht über das Kippen des Geräts gesteuert wird. Entsprechend haben wir vier Benutzeroberflächen entwickelt (Standard, SDAZ, Stiftdruck und Kippen) und diese in einer Nutzerstudie mit 32 Probanden getestet. Die Ergebnisse zeigen, dass SDAZ eine effektive Bearbeitung von simplen Schnelligkeitsaufgaben als auch von komplexeren Navigationsszenarien ermöglichte, jedoch das Koppeln von Zoomen und Pannen dennoch zu einer hohen Nutzerfrustration führte. In einer Präferenzbefragung bezüglich der getesteten Benutzeroberflächen zeigten die Probanden eine starke Ablehnung gegen SDAZ und erklärten, dass sie die Oberfläche schwer und umständlich zu bedienen fanden. Im Vergleich dazu wurden die neuartigen Interaktionvarianten Stiftdruck und Kippen ausgesprochen gut angenommen. Allerdings machten die Probanden während des Tests kaum Gebrauch von der angebotenen parallelen Interaktion. Dies führte bei einem 600x600 pixel grossen Sichtfenster zu ähnlichen Lösungszeiten wie für die Standardbenutzeroberfläche. Letztere stellte sich für ein 300x300 pixel grosses Sichtfenster sogar als die signifikant schnellere Variante heraus. Dieses Verhältnis wird auch durch die Präferenzwahl widergespiegelt. Während für das grössere Sichtfenster die Kippvariante die bevorzugte Technik war, erhielt für das kleinere Sichtfenster die Standardvariante die meisten Stimmen. Wir vermuten daher, dass auf einem kleineren Bildschirm, präzise Interaktion einen relativ höheren Einfluss verglichen mit dynamischer Interaktion auf die Nutzungsqualität hat.
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ABSTRACT: Previous research has shown that Alphasliders are an effective tool for searching an alphabetically sorted list when only limited screen space is available for the graphical user interface. To improve user satisfaction, we propose equipping the widget with a novel text filter to dynamically limit the slider range. In this way, users are supported in locating target items and in identifying records that are missing. The results of a comparative user evaluation run on a Personal Digital Assistant showed that 8 out of 12 participants preferred the filter widget to the classic interface. We further suggest an enhanced Alphaslider design to speed up user interaction.
First publ. in: Proceedings / IEEE Conference on Information Visualisation, 2007, pp. 145-149.
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ABSTRACT: ZuiScat is a visualization concept for querying large information spaces on Personal Digital Assistants (PDA). Retrieval results are presented in a dynamic scatterplot, which is enhanced by geometric and semantic zoom techniques to provide smooth transitions from abstract visual encodings to data content. The same visualization is also used to manage bookmarks and to serve as a powerful query history tool. User feedback suggests that ZuiScat provides intuitive and efficient data access but still needs further improvement in terms of zoom usability and visual mapping.
First publ. in: Proceedings of the 7th international conference on human computer interaction with mobile devices & services [Mobile HCI 2005], Salzburg, Austria, 2005, pp. 129-136.
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ABSTRACT: While zoomable user interfaces can improve the usability of applications by easing data access, a drawback is that some users tend to become lost after they have zoomed in. Previous studies indicate that this effect could be related to individual differences in spatial ability. To overcome such orientation problems, many desktop applications feature an additional overview window showing a miniature of the entire information space. Small devices, however, have a very limited screen real estate and incorporating an overview window often means pruning the size of the detail view considerably. Given this context, we report the results of a user study in which 24 participants solved search tasks by using two zoomable scatterplot applications on a PDA - one of the applications featured an overview, the other relied solely on the detail view. In contrast to similar studies for desktop applications, there was no significant difference in user preference between the interfaces. On the other hand, participants solved search tasks faster without the overview. This indicates that, on small screens, a larger detail view can outweigh the benefits gained from an overview window. Individual differences in spatial ability did not have a significant effect on task-completion times although results suggest that participants with higher spatial ability were slowed down by the overview more than low spatial-ability users.
First publ. as paper in: Proceedings of the working conference on advanced visual interfaces, AVI 2006, Venezia, Italy, May 23-26, 2006, pp. 233-240.
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ABSTRACT: Existing information-visualization techniques that target small screens are usually limited to exploring a few hundred items. In this article we present a scatterplot tool for Personal Digital Assistants that allows the handling of many thousands of items. The application's scalability is achieved by incorporating two alternative interaction techniques: a geometric-semantic zoom that provides smooth transition between overview and detail, and a fisheye distortion that displays the focus and context regions of the scatterplot in a single view. A user study with 24 participants was conducted to compare the usability and efficiency of both techniques when searching a book database containing 7500 items. The study was run on a pen-driven Wacom board simulating a PDA interface. While the results showed no significant difference in task-completion times, a clear majority of 20 users preferred the fisheye view over the zoom interaction. In addition, other dependent variables such as user satisfaction and subjective rating of orientation and navigation support revealed a preference for the fisheye distortion. These findings partly contradict related research and indicate that, when using a small screen, users place higher value on the ability to preserve navigational context than they do on the ease of use of a simplistic, metaphor-based interaction style.
IEEE Transactions on Visualization and Computer Graphics 12(5):829-36. · 2.21 Impact Factor
