Usability Analysis of Custom Visualization Tools

Many visualization tools allow the implementation of custom (non-standard) visualizations, but they differ in approach. The approaches vary from imperative to declarative programming. Moreover, some tools provide environments that assist designers in implementing visualizations. Which approach supports designers best in implementing custom visualizations? What is lacking? To answer these questions, we compared the approaches of four recent visualization tools that support custom visualizations using an example. Further, we evaluated the approaches using the framework of the Cognitive Dimensions of Notations (CDs). Our findings favour notations that use declarative rather than imperative programming, and environments that allow exploration rather than dialogue-dependant ones.