In the last few years, multi-touch has become the default mode of interaction not only for portable devices such as smartphones and tablets, but also for interactive tabletops and wall displays. Changes are also expected to happen with desktops as touch-enabled monitors become more affordable and readily available. Controlling everything with fingers instead of a single, indirect mouse cursor drastically changes the requirements and capabilities of interfaces. These changes present both opportunities and challenges for information visualization, where interactions are still predominately mouse and keyboard; we need to rethink those interfaces. Given the wide variety and complexity of existing visualization techniques, it is probably not feasible to create a single set of multi-touch interactions that can cover all visualizations. To consider generalizing touch interactions across visualizations, we therefore need more concrete practical examples. In this paper, we add to the small existing set of multi-touch enabled visualizations by extending one specific visualization technique, stacked graphs, which is commonly used and yet could significantly benefit from multi-touch interactions.
Despite their popularity, stacked graphs suffer from issues with legibility, enabling comparisons, and scalability. With the design and development of TouchWave, we show how bringing stacked graphs to multi-touch capable tablet computers to address their inherent issues requires a complete rethinking of the visualization, in both representation and interaction. In addition, we demonstrate how we address stacked graph issues with a simple yet comprehensive set of touch-based interactions.
The main contributions are: TouchWave, which extends capabilities of stacked graphs by introducing a set of consistent multi-touch interactions that mitigate several basic stacked graph problems; a collection of touch interaction design goals, which consider particularly the issues of creating a hands-on-data visualization experience; and the concept of kinetic manipulation, which encourages combining the active physical finger, hand, and body motions with the animated responses of the visualization to enhance an experience of virtual tangibility.
I re-recorded the conference talk for all your enjoyment and it's up on vimeo:
TouchWave: Kinetic Multi-Touch Manipulation for Hierarchical Stacked Graphs In ACM International Conference on Interactive Tabletops and Surfaces - ITS 2012. Boston, MA, USA, ACM Press, 10 pages, November 11-14.