中文摘要：

层次数据是生产和生活中常见的一类数据.树可视化通常用于呈现层次数据,是可视分析中的一个重要部分.比较是一种常用的分析方式,而树比较可视化也是可视分析研究中的一个重要课题.树比较可视化从所比较的树的数目角度,分为树内比较、两树比较和多树（3树及以上）比较;从数据特点角度分为静态树比较和动态树比较;从比较分析的任务角度,分为结构比较和属性比较.对现有的树比较可视化方法进行了总结,按照不同方法的表现形式,将树比较可视化分为并置、合并以及动画这3类.同时,结合其他分类方法对树比较可视化方法进行了全面的分析和评估.通过评估和比较,分析了不同方法的优缺点以及在不同的数据分析需求中的适用性.在此基础上,还对树比较可视化中的交互方式进行了总结,并阐述了树比较可视化所面临的挑战.

英文摘要：

Hierarchical data is very common in daily life, and tree visualization, which is used to represent hierarchical data, is an important part of visual analysis. While comparative analysis is widely used in problem solving, tree comparison plays an important role in visual analysis. From the perspective of comparing tree numbers, there are inter-tree comparison, pair-wise comparison and multi-tree comparison. Taking data characteristics into consideration, static tree comparison and dynamic tree comparison can be applied. Tree comparison can also be classified into structure comparison and attribute comparison according to comparison tasks. This paper provides an overview of the tree comparison methods relating to visualization area. These methods are divided into three categories according to their representation： juxtaposition, superposition and animation. The paper analyzes both advantages and disadvantages of different approaches, and then gives suggestions in different situations. It concludes with a discussion about the interactive explorations and the challenges of tree comparison.