Bidirectional Squarified Treemap Algorithm

With the further penetration and development of computer application technology, visualization gradually became a research focus in computer application research field. One of the important subjects in visualization is the visualizing of hierarchical data set, which comprised techniques such as list, outline, node-link diagram and newly invented treemap.Treemap, a visualization technique based on 2d space filling, with its significant feature of more effectively ultilizing every pixels in the display space compared with other traditional techniques, was more suitable for visualizing large hierarchical data set. There had been many algorithms for generating treemap, including cushion algorithm for enforcing the ability to illustrate hierarchical information, squarified algorithm for reducing the aspect ratios, pivot algorithm and strip algorithm for remeding the shortcoming of squarified algorithm for losing the order information. This paper analyzed and compared these algorithms, and presented bidirectional squarified algorithm via the analysis of squarified algorithm. Bidirectional squarified algorithm implemented a bidirectional strategy to optimize the layout of rectangles in every step, and defined a layout threshold to minimize the time complexity and further control the layout of rectangles. Through simulating experiments, we testified the average aspect ratios reduction and better stability of bidirectional squarified algorithm compared with squarified algorithm.Grounded on the theoretical study on treemap algorithms, we incarnated a treemap prototype - treemap 1.0, which integrated several main treemap algorithms. Treemap 1.0 demonstrated the effectiveness of treemap technique through typical applications, purveying an ideal platform for studying treemap algorithms. Under treemap 1.0, combining the feedback of users, we performed further analysis and compares in bidirectional and other algorithms. The results indicated that bidirectional algorithm can eventually achieve the least aspect ratios, while suffered less order property and dynamic stability comparing to other algorithms, just as squarified algorithm did. To therapy the less dynamic stability of bidirectional squarified algorithm, we posed several possible solutions. Meanwhile, we...