Abstract: How to display a large tree in the limited screen while maintaining its hierarchical structure clearly in order to avoid cognitive difficulties has been one of the main research topics of tree visualization. The improved Space-Optimized Tree（SOT） method presented in the paper further optimizes the space utilization through more reasonable space division, meanwhile, it further reduces the recognition burden due to the irregular distribution of the leaf nodes on original SOT tree through the regular positioning of them.

Key words: visualization, structure visualization, tree visualization, space-optimized layout

摘要： 如何在有限的屏幕空间呈递层次规模尽可能大的树并保持其清晰的层次结构以避免认知困难问题一直是树可视化研究的主要问题之一。提出的改进的空间优化的树方法采用更合理的子树空间划分，进一步提高空间利用率，通过改变边缘结点定位方式进一步降低了原方法中因其分布不规则性而造成的认知负担问题。

关键词: 可视化, 结构可视化, 树绘制, 空间优化布局