2-D: Focus Context

1
2-D FocusContext

• cs5984 Information Visualization
• Chris North

2
Wendy Schafer

• Moosburg
• moosburg.cs.vt.edu

3
Today

• Robertson, Document Lens, p 562
• ashwini, aejaaz
• Spence, Bifocal Lens, p 331,333

4
FocusContext

• Details within overview
• Distortion-oriented display
• Fisheye
• Leung, Apperley, Taxonomy of distortion-oriented
  presentations, book pg 350

5
Visual Transfer Functions
Display surface
Information surface
Identity function normal flat overview
Bifocal
6
Magnification Functions
1st Derivative
7
Bifocal Display

• Spence, Apperley

8
Bifocal Display
Disadvantage 1 dimensional stretching on the 4
sides
9
Perspective Wall / Document Lens
10
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

11
Bubble
Disadvantage local context highly de-magnified
12
Fisheye, wide-angle lens
Disadvantage no flat area
13
Quiz TableLens

• Bifocal!

14
Fisheye Menus

• Non-linear
• combination of Bubble fisheye

15
Why not magnifying glass?

• Hides local context

16
FC vs. OD

• Scales up to larger data (zoom factor and
  chaining)
• Multi foci easier
• multiple overviews possible
• Easy to implement, Less math!
• Fast system performance
• - gt2 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

• 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

17
Assignment

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