In many cases, Tangible User Interfaces allow the manipulation of digital content with physical objects recognized by an interactive tabletop. Usually, such tangible objects are made of opaque wood or synthetic materials, thereby occluding the display. In this paper, we systematically investigate the promising potential of tangibles entirely made of transparent or translucent materials. Besides visualizing content directly below a manipulable tangible, transparent objects also facilitate direct touch interaction with the content below, dynamic illumination and glowing effects. We propose a comprehensive design space for transparent tangibles on tabletops based on a thorough review of existing work. By reporting on our own experiments and prototypes, we address several gaps in this design space, regarding aspects of both interaction and visualization. These include the illumination of tangibles as well as the precise input with transparent tangibles for which we also present the promising results of an initial user study. Finally, benefits and shortcomings of transparent tangibles are discussed and resulting design considerations are presented.

Precise alignment of graphical objects and the creation of accurate layouts are crucial activities in many applications, such as graphics design tools, presentation software or graph editors. Surface computing is very promising for these application domains but not fully explored yet. In this paper we contribute two tools which support layout tasks on interactive displays: interactive grids and multi-touch alignment guides. Both tools allow the precise positioning of graphical objects in a flexible and fluent way by multi-touch input. Direct bimanual interaction and physical metaphors are applied to arrange objects along straight lines and curves. A formative user evaluation showed promising results with regard to a productive and easy use of the tools.

Background: Software product line engineering provides an effective mechanism to implement variable software.However, the usage of preprocessors, which is typical in industry, is heavily criticized, because it often leads to obfuscated code.Using background colors to support comprehensibility has shown effective, however, scalability to large software product lines (SPLs) is questionable.Aim: Our goal is to implement and evaluate scalable usage of background colors for industrial-sized SPLs.Method: We designed and implemented scalable concepts in a tool called FeatureCommander.To evaluate its effectiveness, we conducted a controlled experiment with a large real-world SPL with over 160,000 lines of code and 340 features.We used a within-subjects design with treatments colors and no colors.We compared correctness and response time of tasks for both treatments.Results: For certain kinds of tasks, background colors improve program comprehension.Furthermore, subjects generally favor background colors.Conclusion: We show that background colors can improve program comprehension in large SPLs.Based on these encouraging results, we will continue our work improving program comprehension in large SPLs.Difficulty U value 20.5 24.5 17.5 18 10.

Software product line engineering provides efficient means to develop variable software. To support program comprehension of software product lines (SPLs), we developed View Infinity, a tool that provides seamless and semantic zooming of different abstraction layers of an SPL. First results of a qualitative study with experienced SPL developers are promising and indicate that View Infinity is useful and intuitive to use.

The C preprocessor is often used in practice to implement variability in software product lines. Using #ifdef statements provokes problems such as obfuscated source code, yet they will still be used in practice at least in the medium-term future. With CIDE, we demonstrate a tool to improve understanding and maintaining code that contains #ifdef statements by visualizing them with colors and providing different views on the code.

Faceted browsing is a promising way to incrementally refine data sets. Current approaches do not scale well in terms of screen size and have shortcomings in interacting with hierarchical facets. This paper introduces FacetZoom, a novel multi-scale widget combining facet browsing with zoomable user interfaces. Hierarchical facets are displayed as space-filling widgets which allow a fast traversal across all levels while simultaneously maintaining context. We contribute both a seamless continuous navigation and a quick tap-and-center interaction. Two prototypes are described which successfully apply the space-structuring widget to continuous, sampled data and an information collection. A formative user study of the latter indicates that the interface scales well to small screens. FacetZoom is versatile and offers consistent searching and browsing behaviors in a multitude of applications and device settings.

Current mobile music players and managers rely on scrolling long and hierarchically structured lists of items. They do not scale well to various screen sizes. As a solution, this paper introduces Mambo for browsing personal music collections on mobile and other devices. Songs, albums, or artists can be browsed and filtered according to different hierarchical metadata facets such as time, genre, or alphabet. The FacetZoom widget constitutes the basic metaphor and combines visual faceted browsing with zoomable user interfaces. To search, browse, and filter data in a consistent way, we contribute both a continuous multi-scale and a discrete tap-and-center navigation which is especially suited for mobile devices. A 24-subject formative user study was conducted, investigating the first prototype under PDA and Ultra Mobile PC display conditions using two design variants. The results indicate that the facet-based zooming approach scales well to various display sizes.