【作者】 任磊； 王威信； 滕东兴； 马翠霞； 戴国忠；

【Author】 Ren Lei +, Wang Weixin, Teng Dongxing, Ma Cuixia, Dai Guozhong (Intelligence Engineering Laboratory, Institute of Software, the Chinese Academy of Sciences, Beijing 100080, China)

【机构】 中国科学院软件研究所人机交互技术与智能信息处理实验室；

【摘要】 本文针对层次结构信息可视化的嵌套圆可视化方法进行优化改进。主要对于树结构同层兄弟节点的外切圆排列算法在排列中心、外切排列顺序等方面进行优化;并针对树结构不同层父子节点的嵌套圆递归排列算法在嵌套圆排列分布等方面进行优化。实验表明,优化后的方法能够提供更紧密的外切排列效果,提高空间利用率,并且呈现更为有序的可视化视图,更利于用户认知。可用性评估表明,优化后的方法获得了更高的任务完成效率和更高的用户满意度。更多还原

【Abstract】 The visualization of hierarchical information structures plays more and more important role in the information visualization community. All kinds of visualization methods have been developed for the visualization of large hierarchies in a small display, among which, space-filling visualization has been admittedly thought of as one of classical methods. We proposed a space-filling visualization method for large hierarchies by packing nested circles. The brother nodes at the same level are represented by externally tangent circles and the tree nodes at different levels are displayed by packing nested circles. This approach is similar to Treemaps method, which provides good overviews for large hierarchical data sets. And with nested circles instead of rectangles, it makes it easier to see groupings and structural relationships. However, this approach has two drawbacks as follows. On one hand, the algorithm of packing brother nodes at the same level does not adapt well to packing a group of circles which have a great difference in radii. As a result, the shape of packing layout of a group of circles with random radii by the algorithm tends not to be like a circle. So the irregular shape of the circles’ group will occupy more display space. On the other hand, the algorithm of packing tree nodes at different levels layouts the nested circles without any order, which often leads to that the nodes with much information are arranged far way from the center of the display space. In consequence, the disordered layout of nested circles makes user feel confused and augments the cognition burden. In this paper, motivated by the problems above, the algorithm of packing brother nodes at the same level and the algorithm of packing tree nodes at different levels are improved to optimize the method of tree visualization by packing nested circle. As for the first problem, an improved algorithm of packing brother nodes at the same level is presented. First a group of circles are sorted in descend order by radii and the center of the biggest circle is taken as the origin of circles’ group. Then the circles in turn are packing externally tangent to the circles’ group in descend order. As for the second problem, an improved algorithm of packing tree nodes at different levels is described. The nodes at every level are sorted in descend order by size before the correspond nested circles are packing. Therefore, the more information a node has, the closer the node is to the center of display space, which could enhance user’s cognition of tree structure. We implement all algorithms above using VC++ 6.0. Experiment results show that the improved algorithms lead to a more compact visualization of tree structure and allow a smaller circle to contain the externally tangent circles’ group, so it has a more efficient use of display space. Besides, the ordered layout by the improved algorithms gives a clearer visualization of large hierarchical information structures更多还原