DATA VISUALIZATION. Lin Lu Lecture 9--Information Visualization. Interaction

Transcription

1 DATA VISUALIZATION Lecture 9--Information Visualization Interaction Lin Lu

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 8/ This lecture looks at two concepts: Focus and context Brushing

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)

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 (

5 Bifocal Display Implemented as an image browser that scales different areas of image in different ways Chris North, Univ of Maryland Available at:

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

7 What is the Bifocal Display Doing? Transforming the information space to the display space Visual transfer functions Display Space Normal display Information space Display Space Bifocal display context Information space focus

8 Developing the Idea Card, Robinson and McKinlay developed the idea into the Perspective Wall ENV

9 The Perspective Wall 2D layout wrapped around a 3D structure Space utilisation: -detail on centre panel 3x size of equivalent flat wall fitting field of view

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

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 Display Space Perspective Wall context Information space focus

12 FishEye Menus Here is the same idea applied to menus Ben Bederson, University of Maryland Reference: Bederson, B. B. (November 2000) Fisheye Menus Proceedings of ACM Conference on User Interface Software and Technology (UIST 2000), pp , ACM Press.

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: u/fisheyemenu-demo.shtml

14 Menus arrow scroll hierarchical fisheye

15 Table Lens This is a focus and context idea specifically aimed at tables Try codes at:

16 Table Lens

17 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:

18 Rapid Zooming Interfaces There is often a blurred distinction between zooming interfaces and distortion techniques Look at: ml New buzzword: ZUIs

19 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?

20 Multiple Views Multiple views can also be used to provide focus and context Powerpoint uses this to good effect!

21 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 ml ENV

22 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

23 Linking: Brushing Brushing has become a fundamental concept in visualizing information Already encountered in xmdvtool

24 Linking: Coordinated Views Selection from one view can be linked to a corresponding selection in another view Coordinated multiple views

25 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?

26 Snap Together for Directories