Protovis: A Graphical Toolkit for Visualization

Despite myriad tools for visualizing data, there remains a gap between the notational efficiency of high-level visualization systems and the expressiveness and accessibility of low-level graphical systems. Powerful visualization systems may be inflexible or impose abstractions foreign to visual thinking, while graphical systems such as rendering APIs and vector-based drawing programs are tedious for complex work. We argue that an easy-to-use graphical system tailored for visualization is needed. In response, we contribute Protovis, an extensible toolkit for constructing visualizations by composing simple graphical primitives. In Protovis, designers specify visualizations as a hierarchy of marks with visual properties defined as functions of data. This representation achieves a level of expressiveness comparable to low-level graphics systems, while improving efficiency-the effort required to specify a visualization-and accessibility-the effort required to learn and modify the representation. We substantiate this claim through a diverse collection of examples and comparative analysis with popular visualization tools.

尽管有无数用于可视化数据的工具，但高级可视化系统的符号效率与低级图形系统的表现力和易用性之间仍然存在差距。强大的可视化系统可能不够灵活，或者强加一些与视觉思维相悖的抽象概念，而诸如渲染应用程序编程接口（APIs）和基于矢量的绘图程序等图形系统对于复杂工作来说又很繁琐。我们认为，需要一种为可视化量身定制的易于使用的图形系统。作为回应，我们推出了Protovis，这是一个通过组合简单图形原语来构建可视化的可扩展工具包。在Protovis中，设计人员将可视化指定为标记的层次结构，其视觉属性被定义为数据的函数。这种表示方式达到了与低级图形系统相当的表现力水平，同时提高了效率（指定可视化所需的工作量）和易用性（学习和修改表示方式所需的工作量）。我们通过大量不同的示例以及与流行可视化工具的比较分析来证实这一说法。