The power of interactively linked hierarchy visualizations

This paper describes an interactive web-based tool for visualizing hierarchical data including the recently developed concept of space-reclaiming icicle plots and several more traditional hierarchy visualizations. The tool provides ways to upload, share, explore, and compare hierarchical data using a multitude of different linked hierarchy visualizations. The current version supports up to eight hierarchy visualizations, focusing on user-friendly interactive navigation by a dynamic graphical user interface with a variety of functions while each visualization is interactive by itself. Moreover, color deficiency issues are taken into account in the tool, further improving the usability for this user group. All of the visualizations can be shown in linked views while typical hierarchy parameters and visual variables can be changed on user demand. The interactive tool makes use of OpenGL and Angular, an industry standard JavaScript platform, and runs in a web browser. We illustrate the usefulness of the visualization tool by applying it to the NCBI taxonomy that consists of more than 300,000 hierarchically organized species while filtering for the tetrapoda subhierarchy as an application example. To further test the usability of the tool we did a performance test with increasing sizes of processed hierarchy datasets and even support a GPU implementation. Also user feedback on the eight visualizations was collected. Finally, we explain implementation details and discuss limitations and scalability issues of the linked visualization techniques.