Information Visualization Concepts covered What is Information Visualization

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 James Tam

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

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

Which is the best flight? length, stop-overs, switches. . . depart arrive AC 117 Vancouver - Calgary 7: 00 9: 00 Cdn 321 Vancouver - Calgary 9: 00 12: 00 Cdn 355 Calgary - Montreal 13: 30 19: 30 AC 123 Calgary - Toronto 12: 30 16: 30 AC 123 Toronto - Montreal 16: 45 17: 30 *time zone: +1 van-cal, +2 cal-tor, mtl Vancouver 7 9 AC 117 Calgary 8 11 13 15 17 14 16 18 Cdn 321 10 12 Cdn 355 AC 123 Toronto Montreal 10 12 14 16 18 20 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. 5 X Graphics Reveal the Data 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 E. Tufte Visual Display of Quantitative Information note: many visual examples on the following slides are taken from Tufte’s books James Tam

Show The Data # Buffalo # Adults # calves James Tam

Not Get In The Way Of The Message James Tam

Avoid Distortion James Tam

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

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

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

Broad Overview And Fine Detail James Tam

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

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

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

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

Shape James Tam

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

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

Color James Tam

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

James Tam

James Tam

Visual Variable: Orientation selective associative quantitative order 17 15 < < < ? 95 < < James Tam

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

Texture: Vibratory Effects 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 James Tam

Motion 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? James Tam