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Browsing Hierarchical Data with Multi-level Dynamic Queries and Pruning. By H. P. Kumar, C. Plaisant & B. Schneidernam Presented by: Dawit Yimam Seid. Tree Representations. Node-link visualization 2D (outline, tree diagrams) 3D (Cone Trees) Tree-map visualization (nested & non-nested)
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Browsing Hierarchical Data withMulti-level Dynamic Queries and Pruning By H. P. Kumar, C. Plaisant & B. Schneidernam Presented by: Dawit Yimam Seid
Tree Representations • Node-link visualization • 2D (outline, tree diagrams) • 3D (Cone Trees) • Tree-map visualization (nested & non-nested) • Graph structures (hypertext, flow charts, etc.) ICS 280 - Info Visualization
HDS/Tree Browsing “Hierarchical browsing” • interaction matches structure • When do we do hierarchical browsing ? • “hierarchical decision making”, iterative refinement/progressive querying of datasets • e.g. sales & budget data, catalog of products, computer file systems • most AND queries can be considered hierarchical e.g. “SEX=male AND M_STATUS=single AND INCOME>=200,000” ICS 280 - Info Visualization
Tree Browsing - requirements • Somewhat contradictory • Retain context - not getting lost deep in the tree vs. • Don’t display non-relevant information • How to achieve both at the same time ? ICS 280 - Info Visualization
PDQ Tree-Browser’s Approach • Enable viewing tree at different levels • Selection (filtering) criteria at various levels in the tree • attribute based specification of the foci of interest • Hide uninteresting nodes and branches rapidly ICS 280 - Info Visualization
PDQ Tree-Browser Techniques • Dynamic Queries & tight coupling • let users dynamically query nodes at each level • tightly couple query widgets to tree visualization • tightly couple the overview and detail views • Automatic Pruning (in addition to zooming and panning) • automatically prune out uninteresting nodes/sub-trees to get more compact views ICS 280 - Info Visualization
Dynamic Queries for Tree Browsing • Applying DQ to trees is challenging ! • Predefined relationships between data points (unlike the case of flat/independent data sets). A query at one node affects other nodes • Dynamic generation of widgets since • nodes at different levels can have different attributes, and • since these nodes are dynamic ICS 280 - Info Visualization
The PDQ Tree-Browser Interface • Data display - two resizable windows • Overview (left) • Detail view (right) • Dynamic Query Panel • Attribute list (shows attributes of the current lowest level) • Widgets panel - widgets created by users • range-sliders (for numeric) • menu (for text) ICS 280 - Info Visualization
The PDQ Tree-Browser Interface Detailed view Overview Field-of-view Level name button Level increment/ decrement Widgets Panel Attributes List Feedback Indicator ICS 280 - Info Visualization
Query & Manipulation • Query using Widgets • Queries AND-ed together and matching nodes colored yellow in real time • Manipulating a widget at an internal node level makes that node the current lowest level • Tree structure changed through • level buttons • widgets • + or - buttons • pan detail view dragging the field-of-view • Two types of coupling ! ICS 280 - Info Visualization
Pruning • Done when depth of the tree is increased. • Children of non-matching nodes are pruned • Orange shows non-pruned nodes ICS 280 - Info Visualization
Example Application The UniversityFinder
PDQ Tree-Browser Limitations • Max depth of 5 • only up to 3 attributes to query; queries only AND-ed • scrolling the overview needed when tree is large • Clicking nodes in detail view do not open their sub-trees ICS 280 - Info Visualization
Issues/Alternatives • Pruning Vs. graying out ? • To change tree structure as widgets are created or not ? • How to handle large trees ? • Maintain overview to detail view coupling ? • Intermediate views, let user restrict before display • How to generalize the PDQ Tree-Browser to other tree representations (e.g. treemap) • where to place widgets ? How to prune ? • How to add OR and NOT queries ? ICS 280 - Info Visualization
Usability Testing • 8 subjects (2 pilot, 6 test) • 7 tasks (feature based & task-based) • Results (on a scale of 1-9) • 8.7 - pruning (+“Hide Grey Leaves”) is useful • 8.2 - dynamic query is useful • 4.8 - easiness of range-slider manipulation • Some users did not like the dynamic widget creation ! ICS 280 - Info Visualization
Controlled Experiment Goal - compare Full-tree, Partially-pruned tree and Fully-pruned tree • 25 subjects; 7 tasks • Results • Task completion time 1. Fully-pruned 2. Partially-pruned 3. Full-tree • Subjective satisfaction rate 1. Partially-pruned 2. Fully-pruned 3. Full-tree • No clear cut finding on graying Vs. hiding pruned nodes ICS 280 - Info Visualization