Radial Icicle Tree (RIT): Node Separation and Area Constancy

Yuanzhe Jin, Tim de Jong, Martijn Tennekes, Min Chen

DOI: 10.1109/TVCG.2023.3327178

Room: 105

2023-10-25T00:33:00ZGMT-0600Change your timezone on the schedule page
2023-10-25T00:33:00Z
Exemplar figure, described by caption below
The Radial Icicle Tree (RIT) elucidates the connections and distinctions between various categories within the dataset. Through the implementation of RIT, we visualized data from the CBS dataset, which was aggregated from wearable devices adorned by volunteers in a laboratory setting. RIT plots were utilized for eight categories of human physical activity, unveiling inter-category relationships. This underscores one of the key benefits of RIT - the ability to swiftly and lucidly reveal intrinsic data relationships when structural connections are present. It also facilitates simple comparisons between diverse plot categories concurrently, enabling users to uncover intriguing relations among them.
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Keywords

Tree visualization, icicle tree, sunburst tree, size encoding, area constancy, node separation, radial icicle tree, RIT

Abstract

Icicles and sunbursts are two commonly-used visual representations of trees. While icicle trees can map data values faithfully to rectangles of different sizes, often some rectangles are too narrow to be noticed easily. When an icicle tree is transformed into a sunburst tree, the width of each rectangle becomes the length of an annular sector that is usually longer than the original width. While sunburst trees alleviate the problem of narrow rectangles in icicle trees, it no longer maintains the consistency of size encoding. At different tree depths, nodes of the same data values are displayed in annular sections of different sizes in a sunburst tree, though they are represented by rectangles of the same size in an icicle tree. Furthermore, two nodes from different subtrees could sometimes appear as a single node in both icicle trees and sunburst trees. In this paper, we propose a new visual representation, referred to as radial icicle tree (RIT), which transforms the rectangular bounding box of an icicle tree into a circle, circular sector, or annular sector while introducing gaps between nodes and maintaining area constancy for nodes of the same size. We applied the new visual design to several datasets. Both the analytical design process and user-centered evaluation have confirmed that this new design has improved the design of icicles and sunburst trees without introducing any relative demerit.