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

1st Derivative

Bifocal Display

• Spence, Apperley

Bifocal DisplayDisadvantage: 1 dimensional stretching on the 4 sides

Perspective Wall / Document Lens

NonLinear Magnification• http://www.cs.indiana.edu/hyplan/tkeahey/research/nlm/nlm.html

• http://www.cs.indiana.edu/hyplan/tkeahey/research/papers/infovis.98.html

“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