1. Visual Overview Strategies cs5984: Information Visualization Chris North

2. Homework 1 Grading: +, , -, 0 Tablelens + Shows all attributes simultaneously (overview) Sorting: relates 1 attribute  Many attributes Spotfire + multiple representations (scatter, 3D, bar, histo, …) + details-on-demand better than Tablelens F+C - scatterplot 2D occlusion problem Scatter: relates 1 attribute  1 attribute Strategy: First: Tablelens for overview Then: Spotfire for detail analysis

3. Visual Overview Design Goals Visual: take advantage of human visual processing Information Rich: show as much as you can! (while maintaining a clean design) Interaction Affordances: enable quick access to details E.g. Zooming, Overview+Detail, Focus+Context

4. Visual Overview Advantages Helps solve the Keyhole Problem: Map, organization (spatial layout of concepts) What information is (not) available? Adds context info, relationships Enables direct access Encourages exploration HCI metrics: Improves user performance, learning time, error rates, retention, satisfaction –Studies, e.g. Beard & Walker, Chimera, North, etc.

5. Strategy Strategy 1: Display everything! Only works for small scale Strategy 2: Reduce scale to fit screen Reduce items Reduce attributes Reduce value “size”

6. Strategies Filtering Aggregation / Abstraction Reduced Representation

7. Filtering Filter attributes Scatterplot: selects 2 attributes, ignores rest Filter items VIDA (Visual Info Density Adjuster): show high priority items, representative set (video) Human-Eye View: focused info density

8. Aggregation Aggregate items Grouping several items into one (e.g. SQL “group by”) –Snap-Together Visualization: overview+detail, drill down Semantic zooming –Pad++ (Abstraction) –Lifelines? –NetViz Aggregate attributes Star Coordinates

9. Reduced Representation Stasko, “Information Mural”, web » sanjini, luhui

10. Assignment - Trees Read for Tues Rao, “Hyperbolic Tree”, book pg 382 » Joy, maulik Kumar, “Multi-level DQ and Pruning”, book pg 295 Read for Thurs Johnson, “Treemaps”, book pg 152 Stasko, “Sunburst”, web » Marcus, marty Project groups meet with me early next week

11. Homework #2 Due: Thurs March 1 (1 week) Visualization Design Visualizing timed paths –(the bus schedule problem!)