ENV 2006 7.1

Envisioning Information

Lecture 7 – Interaction

Ken Brodliekwb@comp.leeds.ac.uk

ENV 2006 7.2

Interaction

• Major difference between paper and computer-based visualization is ability to interact with picture and alter the presentation of the data

• Nice simple example is ‘Dancing with Histograms’– Dix and Ellis

http://www.comp.lancs.ac.uk/computing/users/dixa/papers/simple98/

• This lecture looks at two concepts:– Focus and context

– Brushing

ENV 2006 7.3

Focus and Context

• A recurring problem in Information Visualization is lack of screen real estate

• Challenge has been addressed in some innovative ways• Want to achieve:

– Focus: to see detail of immediate interest– Context: to see the overall picture

• Want to do this interactively…• Six approaches:

– Distortion– Rapid zooming– Elision– Multiple windows– Use 3D (more space)– Use animation (more time)

ENV 2006 7.4

Distortion: Bifocal Display

• As name suggests, distortion achieves aim by magnifying focus area and demagnifying surrounding context

• Probably the first suggestion was the bifocal display of Spence and Apperley (1982)

– Play Spence bifocal_lens movie (http://www.iis.ee.ic.ac.uk/~r.spence/videos.htm)

ENV 2006 7.5

Bifocal Display

• Implemented as an image browser that scales different areas of image in different ways

– Chris North, Univ of Maryland

Available at:http://people.cs.vt.edu/~north/infoviz/

ENV 2006 7.6

Bifocal Display

• A possible application is in map reading

• This London underground application was developed by Marcelo Cohen in Leeds

• Zoom / pan

• Focus /context

ENV 2006 7.7

What is the Bifocal Display Doing?

• Transforming the information space to the display space

– Visual transfer functions

Informationspace

DisplaySpace Normal

display

Informationspace

DisplaySpace

Bifocaldisplay

context

focus

ENV 2006 7.8

Developing the Idea

• Card, Robinson and McKinlay developed the idea into the ‘Perspective Wall’

ENV 2006 7.9

The Perspective Wall

2D layout wrappedaround a 3D structure

Space utilisation:-detail on centrepanel 3x size ofequivalent flat wall fitting field ofview

ENV 2006 7.10

Perspective Wall

• Advantages:– User can adjust ratio of

detail to context– Smooth animation helps

user perceive object constancy

– Relationship between detail and context is consistent: objects bend around the corner

ENV 2006 7.11

Perspective Wall

• In terms of transfer function, the situation is closer to the early Spence movie

– Perspective gives smoother transition from focus to context

Informationspace

DisplaySpace

PerspectiveWall

context

focus

ENV 2006 7.12

FishEye Menus

• Here is the same idea applied to menus– Ben Bederson, University of Maryland

• See also:– http://www.samuelwan.com/downloads/com.samuelwan.eidt/

fisheyemenu/FisheyeMenuDemo.html

ENV 2006 7.13

Comparison of Menu Styles

• Research pages at University of Maryland include a nice applet that allows you to compare different menu styles

– Arrow bar– Scroll Bar– Hierarchical– FishEye

• Screenshots on next slide created from:

– http://www.cs.umd.edu/ hcil/fisheyemenu/ fisheyemenu-demo.shtml

ENV 2006 7.14

Menus

arrow scrollhierarchical

fisheye

ENV 2006 7.15

Question

• What are the disadvantages of the magnifying glass paradigm for providing focus and context?

ENV 2006 7.16

Table Lens

• This is a focus and context idea specifically aimed at tables

• Try applet at:http://www.inxight.com/products/sdks/tl/

ENV 2006 7.17

Table Lens

ENV 2006 7.18

Rapid Zooming Techniques

• Idea is to allow rapid zooming between focus and context– Zoom in to focus, then out to context

• Recent idea is SDAZ – Speed Dependent Automatic Zooming– Linked to scroll bar

– Moving scroll bar fast will zoom out

– Slowing scroll bar will zoom in again

– See: http://www.cosc.canterbury.ac.nz/andrew.cockburn/liter.html

ENV 2006 7.19

Rapid Zooming Interfaces

• There is often a blurred distinction between zooming interfaces and distortion techniques

• Look at:http://www.cs.umd.edu/hcil/piccolo/index.shtml

New buzzword: ZUIs

ENV 2006 7.20

Elision Techniques

• Hide parts of a structure until they are needed• Widely used in graph drawing software for very large graphs• Have you seen this in xmdvtool?

ENV 2006 7.21

Multiple Views

• Multiple views can also be used to provide focus and context

• Powerpoint uses this to good effect!

ENV 2006 7.22

Move into 3D: Cone Trees

• Using a third dimension allows us to prioritise the focus (foreground) without losing the context (background)

• For large tree structures it is impossible to find sufficient screen space

• Cone trees in 3D provide a solution

• Here is a movie

http://research.compaq.com/SRC/3Danimate/conetree.html

ENV 2006 7.23

Adding a time dimension: RSVP

• We can gain more space by adding time!

• Recent Spence work addresses problem of browsing information spaces– Rapid Serial Visual Processing

– To gain a quick view of what is available

– Distinction between browsing and searching– Here is the movie (http://www.iis.ee.ic.ac.uk/~r.spence/videos.htm)

ENV 2006 7.24

Browsing the Web

• Spence has also turned his attention to browsing the web – On mobile devices!– Here is the movie (http://www.iis.ee.ic.ac.uk/~r.spence/videos.htm)

ENV 2006 7.25

Linking: Brushing

• Brushing has become a fundamental concept in visualizing information

– Already encountered in xmdvtool

ENV 2006 7.26

Linking: Coordinated Views

• Selection from one view can be linked to a corresponding selection in another view

– Coordinated multiple views

ENV 2006 7.27

Linking: Multiple Views

• Many of the concepts we have talked about are brought together in the Snap-Together system of Shneiderman and North

• How many visualizations can you recognise here?

http://www.cs.umd.edu/hcil/snap/

ENV 2006 7.28

Snap Together for Directories

ENV 2006 7.29

Linking: Spence Attribute Explorer

• Spence has also developed a tool called Attribute Explorer– Compare it with xmdvtool

– Look for brushing concept– Here is the movie (http://www.iis.ee.ic.ac.uk/~r.spence/videos.htm)