Tu Ying, Shen Han-Wei
Computer Science and Engineering Department, Ohio State, USA.
IEEE Trans Vis Comput Graph. 2007 Nov-Dec;13(6):1286-93. doi: 10.1109/TVCG.2007.70529.
While the treemap is a popular method for visualizing hierarchical data, it is often difficult for users to track layout and attribute changes when the data evolve over time. When viewing the treemaps side by side or back and forth, there exist several problems that can prevent viewers from performing effective comparisons. Those problems include abrupt layout changes, a lack of prominent visual patterns to represent layouts, and a lack of direct contrast to highlight differences. In this paper, we present strategies to visualize changes of hierarchical data using treemaps. A new treemap layout algorithm is presented to reduce abrupt layout changes and produce consistent visual patterns. Techniques are proposed to effectively visualize the difference and contrast between two treemap snapshots in terms of the map items' colors, sizes, and positions. Experimental data show that our algorithm can achieve a good balance in maintaining a treemap's stability, continuity, readability, and average aspect ratio. A software tool is created to compare treemaps and generate the visualizations. User studies show that the users can better understand the changes in the hierarchy and layout, and more quickly notice the color and size differences using our method.
虽然树形图是一种用于可视化层次数据的流行方法，但当数据随时间演变时，用户通常很难跟踪布局和属性的变化。当并排或前后查看树形图时，存在几个问题可能会妨碍查看者进行有效的比较。这些问题包括布局的突然变化、缺乏突出的视觉模式来表示布局以及缺乏直接对比来突出差异。在本文中，我们提出了使用树形图可视化层次数据变化的策略。提出了一种新的树形图布局算法，以减少布局的突然变化并产生一致的视觉模式。提出了一些技术，以便根据地图项的颜色、大小和位置有效地可视化两个树形图快照之间的差异和对比。实验数据表明，我们的算法可以在保持树形图的稳定性、连续性、可读性和平均纵横比方面实现良好的平衡。创建了一个软件工具来比较树形图并生成可视化效果。用户研究表明，使用我们的方法，用户可以更好地理解层次结构和布局的变化，并更快地注意到颜色和大小的差异。
