Tree visualization is a branch of information visualization dedicated to visualizing hierarchy within a dataset. It has widespread applications in visualizing Ancestry, the File System, an Organizational Chart, Internet Addressing, and many more. To adequately represent a particular hierarchical dataset, customization of existing tree layouts or even building a novel tree layout is necessary. A review of the existing information visualization toolkits shows their limitations in providing layout customization and task-specific interaction support for trees. Using the existing toolkits, developers often are required to write code from scratch to implement/customize a tree layout if it is not supported by the toolkit. This process requires significant effort from developers both in terms of coding and in understanding the domain.
This thesis presents findings from usability studies of AVIT – an API for Visualizing and Interacting with Trees. AVIT has been developed with the main focus of providing ease of use to software developers in implementing and customizing different tree layouts with task-specific interaction support. To gather developers’ feedback, two usability evaluations of AVIT were conducted. The first evaluation identified usability problems in AVIT. Based on the feedback, changes were made to the API and the documentation to improve usability. A second evaluation was conducted on an updated version of AVIT to determine what impact the changes had on the usability experience of the API and identified additional usability issues for future iterations of development. Lessons learned from developing and evaluating AVIT are also discussed to aid future work in this area.