|  | Documents Title: 
                Structure-Based Brushes: A Mechanism for Navigating Hierarchically 
                Organized Data and Information Spaces
 Authors: Ying-Huey Fua, Matthew O. Ward and Elke A. Rundensteiner
 Abstract: 
                Interactive selection is a critical component in exploratory 
                visualization, allowing users to isolate subsets of the displayed 
                information for highlighting, deleting, analysis, or focussed 
                investigation. Brushing, a popular method for implementing the 
                selection process, has traditionally been performed in either 
                screen space or data space. In this paper, we introduce an alternate, 
                and potentially powerful, mode of selection that we term structure-based 
                brushing, for selection in data sets with natural or imposed structure. 
                Our initial implementation has focussed on hierarchically structured 
                data, specifically very large multivariate data sets structured 
                via hierarchical clustering and partitioning algorithms. The structure-based 
                brush allows users to navigate hierarchies by specifying focal 
                extents and level-of-detail on a visual representation of the 
                structure. Proximity-based coloring, which maps similar colors 
                to data that are closely related within the structure, helps convey 
                both structural relationships and anomalies. We describe the design 
                and implementation of our structure-based brushing tool. We also 
                validate its usefulness using two distinct hierarchical visualization 
                techniques, namely hierarchical parallel coordinates and tree-maps. 
                Finally, we discuss relationships between different classes of 
                brushes and identify methods by which structure-based brushing 
                could be extended to alternate data structures. Keywords: 
                Brushing, hierarchical representation, interactive selection, 
                exploratory data analysis.  Source: 
                 IEEE Transactions 
                on Visualization and Computer Graphics. (invited paper selected 
                from IEEE Symposium on Information Visualization), May - June 
                2000.  Download: 
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