1. James Tam Information Visualization Concepts covered What is Information Visualization? Tufte's Principles for Information Visualization. Visual Variables. These lecture notes are a chosen selection from the "Representations" lectures from CPSC 481

2. James Tam What Is Information Visualization? Visually representing representing abstract data on a computer in a way that makes it easier to acquire or use the information. From www.bravenet.com

3. James Tam Representations Representation of numbers Decimal: 123456 Binary: 010001 Roman Numerals: IV Different representations have different strengths

4. James Tam Which is the best flight? departarrive AC 117Vancouver - Calgary 7:00 9:00 Cdn 321Vancouver - Calgary 9:0012:00 Cdn 355Calgary - Montreal 13:3019:30 AC 123Calgary - Toronto 12:3016:30 AC 123Toronto - Montreal 16:4517:30 *time zone: +1 van-cal, +2 cal-tor, mtl length, stop-overs, switches... 79 11 13 15 17 1012 14 16 1820 Vancouver 810 12 14 16 18 AC 117Cdn 321 Cdn 355 AC 123 Calgary Toronto Montreal

5. James Tam Anscombe’s Quartet N: 11.0 mean X’s : 9.0 mean Y’s : 7.5 standard error of slope estimate: 0.1 sum of squares: 110.0 regression sum of squares: 27.5 residual sum of squares of Y: 13.8 correlation coefficient: 0.8 r squared: 0.7 regression line: Y=3+0.5X Graphics Reveal the Data

6. James Tam Principles for Information Visualization Graphics should reveal the data show the data* not get in the way of the message* avoid distortion* present many numbers in a small space make large data sets coherent encourage comparison between data supply both a broad overview and fine detail* serve a clear purpose note: many visual examples on the following slides are taken from Tufte’s books E. Tufte Visual Display of Quantitative Information

7. James Tam Show The Data # Buffalo # Adults# calves # Buffalo

8. James Tam Not Get In The Way Of The Message

9. James Tam Avoid Distortion

10. James Tam Broad Overview And Fine Detail Mutually Exclusive Views Icewind Dale (Black Isle)

11. James Tam Broad Overview And Fine Detail Overlay Diablo (Blizzard)

12. James Tam Broad Overview And Fine Detail Separate Views Defender (Williams Electronics)

13. James Tam Broad Overview And Fine Detail

14. James Tam Broad Overview And Fine Detail Bederson, B.B. (May 2000) University of Maryland www.cs.umd.edu/hcil/fisheyemenu/

15. James Tam Visual Variables Position Changes in the x, y, z location Size Changes in length, area or repetition Shape Changes in form Value Changes in brightness Orientation Changes in alignment Colour Changes in hue Texture Variations in pattern Motion www.st-duffer.com

16. James Tam Visual Variables Visual variables can affect how you interpret information selective is a change in this variable enough to allow us to select things from a group? associative is a change in this variable enough to allow us to perceive things as a group? quantitative is there a numerical reading obtainable from changes in this variable? order are changes in this variable perceived as ordered?

17. James Tam Visual Variable: Position selective associative quantitative order 100 0 10 0

18. James Tam selective associative quantitative order Visual Variable: Size > > >>>> =4 X

19. James Tam Selective associative quantitative order Visual Variable: Shape >>>>>>> 15 34 105

20. James Tam Shape

21. James Tam Visual Variable: Value selective associative quantitative order <<<<<< 15 34 105

22. James Tam Visual Variable: Color Selective associative quantitative order > > > > > > > > 15 13 34 67

23. James Tam Color

24. James Tam Encoding Common advice says use a rainbow scale -Marcus, Murch, Healey -problems with rainbows

25. James Tam

27. Visual Variable: Orientation selective associative quantitative order ? << < < <<< 15 1795

28. James Tam Visual Variable: Texture Selective associative quantitative order >>>> 45 15 33

29. James Tam Texture: Vibratory Effects

30. James Tam Visual Variable: Motion selective - motion is one of our most powerful attention grabbers associative – objects moving in unison groups them effectively quantitative - subjective perception order

31. James Tam Motion

32. James Tam Summary How the representation of information can effect the ease to which information can be acquired or used? What are some general guidelines for Information Visualization? What are Visual Variables? How can changes in Visual Variables affect how viewers can interpret information? Which Visual Variables are more effective at different types of visual interpretation tasks?