Cambridge, Massachusetts Perception of Elementary Graphical Elements in Tabletop and Multi-Surface...

Cambridge, Massachusetts

Perception of Elementary Graphical Elements in Tabletop and Multi-Surface Environments

Daniel Wigdor, Chia Shen, Clifton Forlines, Ravin Balakrishnan

CHI 2007

Department of Computer Science, University of Toronto

Acknowledgements

• John Barnwell• John Hancock• MERL & DGP Lab members• Experiment participants

In-Plane Rotation

In-Plane Rotation

NOT THIS PAPER

Planar Rotation

Information Graphics

Encoding & Decoding

15 2823 52

Encoding & Decoding

15 2823 52

Encode

Encoding & Decoding

15 2823 52

Encode

Decode

Cleveland and McGill: Elementary Perceptual TasksBertin: Visual Variables

Visual Variables

Visual Variables • Colour

Visual Variables • Colour• Position

Visual Variables • Colour• Position• Slope

Visual Variables • Colour• Position• Slope• Length

Visual Variables • Colour• Position• Slope• Length• Area

Visual Variables • Colour• Position• Slope• Length• Area• Angle


Modulus:


Modulus:

Stimulus:


Modulus:

Stimulus:

Answer: 38%


Modulus:

Modulus:

Stimulus:


Modulus:

Stimulus:

Answer: 40%


Modulus:Visual Variables • Colour• Position• Slope• Length• Area• Angle

Modulus:

Stimulus:


Modulus:

Stimulus:

Answer: 67%


57

Poor Elementary Perception

58

Slope vs Position

59

Slope vs Position

Experimental Task (Cleveland & McGill)

Conclusions (Cleveland & McGill)

• Error correlated with distance• Rank order of elementary tasks:

1. Position, common scale2. Position, identical nonaligned scales3. Length4. Angle5. Slope6. Area7. Volume, Density, Colour saturation8. Colour hue

Graphical Perception on a Rotated Plane

Vs.

Our Visual Variables:

Experimental Task Example: Line Length

Experiment 1: Single-Screen Comparisons

90° (Vertical)

60°

30°0° (Tabletop)

Hypotheses

I. As the display is tilted, the accuracy of relative magnitude judgements decreases.

Hypotheses

I. As the display is tilted, the accuracy of relative magnitude judgements decreases.

0

2

4

6

8

10

12

14

90 60 30 0

Error %

Err

or

Display Angle

Vertical Tabletop

Hypotheses

II. The up/down distance between objects is positively correlated with the increase in error in magnitude judgements due to screen angle.

Up/DownDistance

ERROR

0

2

4

6

8

10

12

14

16

0cm 14cm 28cmUp/Down Distance

Err

or

: l

Ju

dg

ed

- A

ctu

al

|

90 degrees

60 degrees

30 degrees

0 degrees

Hypotheses

II. The up/down distance between objects is positively correlated with the increase in error in magnitude judgements due to screen angle.

Tabletop

Vertical

Hypotheses

III. Different visual variable types have differing increases in the error in judgements.

Hypotheses

III. Different visual variable types have differing increases in the error in judgements.

0

5

10

15

20

25

0cm 14cm 28cm

Up/Down Distance

Err

or:

| J

ud

ge

d -

Ac

tua

l|

Length (V)

Length (H)

Angle (V)

Angle (H)

Position (V)

Position (H)

Slope

Area

Hypotheses

IV. Sideways presentations of objects experience less error in magnitude judgements due to screen angle than upright presentations.

Hypotheses

IV. Sideways presentations of objects experience less error in magnitude judgements due to screen angle than upright presentations.

0

5

10

15

20

25

Upright Sideways

Length

Angle

Position

Err

or

Hypotheses

V. There will be no effect for side-to-side distance on the accuracy of magnitude perception.

Side-to-sideDistance

slope

area

position

length

angle

Rank Ordering of Visual Variable Perceptibility

Vertical Ranking: Tabletop Ranking:

position (upright)

length (upright)

angle (upright)

slope

area

position (sideways)

length (sideways)

angle (sideways)

position (upright)

length (upright)

angle (upright)

slope

area

position (sideways)

length (sideways)

angle (sideways)

length (upright)

angle (upright)

slope

area

position (sideways)

length (sideways)

angle (sideways)

position (upright)

Rank Ordering of Visual Variable Perceptibility

Vertical Ranking: Tabletop Ranking:

Multi-Surface Environments

Experiment 2: Apparatus

Hypotheses

I. There is an increase in error when comparing visual variable magnitudes between upright and tabletop displays versus comparing on displays of a single orientation.

Hypotheses

II. The error increase when comparing between displays is unevenly distributed across visual variable types.

Hypotheses

II. The error increase when comparing between displays is unevenly distributed across visual variable types.

0

5

10

15

20

25

30

Upright &

Upright

Upright &

Tabletop

Length (U)

Length (S)

Angle (U)

Angle (S)

Position (U)

Position (S)

Slope

Area

Hypotheses

III. The size of the error on the mixed-orientation condition is larger than the largest errors in the previous experiment.

Recommendations

• Mixed-orientation screen comparisons are hard• Ordered list (different than before):

1. length (sideways)

2. length (upright)

3. position (sideways)

4. angle (sideways)

5. area

6. angle (upright)

7. position (upright)

8. slope

Conclusions

• Don’t compare across display orientations• Special visualisations for tabletops & multi-surface spaces

Future Work

Σ= ?

Questions?

Experiment 1 Design

12 participants x

4 display angles x

4 visual variables (per participant) x

3 modulus positions x

9 stimulus positions x

3 magnitude estimates =

15,552 total comparisons

Experiment 2 Design

8 participants x

2 display angles x

8 visual variables x

31 magnitude estimates =

3,968 total comparisons

Cambridge, Massachusetts Perception of Elementary Graphical Elements in Tabletop and Multi-Surface...

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