2-D: Focus+Context cs5984: Information Visualization Chris North

Wendy Schafer Moosburg moosburg.cs.vt.edu

Today Robertson, “Document Lens”, p 562 » ashwini, aejaaz Spence, “Bifocal Lens”, p 331,333

Focus+Context Details within overview “Distortion-oriented display” “Fisheye” Leung, Apperley, “Taxonomy of distortion- oriented presentations”, book pg 350

Visual Transfer Functions Information surface Display surface Identity function = normal flat overview Bifocal

Magnification Functions 1 st Derivative

Bifocal Display Spence, Apperley

Bifocal Display Disadvantage: 1 dimensional stretching on the 4 sides

Perspective Wall / Document Lens

NonLinear Magnification

“Bubble” Disadvantage: local context highly de-magnified

“Fisheye”, “wide-angle lens” Disadvantage: no flat area

Quiz: TableLens Bifocal!

Fisheye Menus Non-linear: combination of Bubble + fisheye

Why not magnifying glass? Hides local context

F+C vs. O+D + Space efficient + Detail connected to context Smooth transition + matches human vision/processing? + Neato! - Distortion - Longer learning time - no flat overview - Need a way to turn off focus - Content moves differently than mouse - hard to tell zoom factor + Scales up to larger data (zoom factor and chaining) + Multi foci easier + multiple overviews possible + Easy to implement, Less math! Fast system performance - >=2 places to look (cross-eyed!) Tracking field-of-view box hard Hand-eye coordination problem - detail and overview disconnected - Windows/space management - replicates detail data in overview

Assignment Read for Thurs (Visual Overview Strategies) Stasko, “Information Mural”, web » sanjini, luhui Project! Mid-project status report: Tues March 27