perspective!!! igor juricevic & john m. kennedy. outline basics of perspective –what is...

Perspective!!!Perspective!!!Igor Juricevic & John M. Kennedy

Outline

• Basics of perspective– What is perspective?– Why study perspective?– Why study perspective pictures?

• Experiments 1-4– The ART theory– Is the ART theory general across observer position?– Is the ART theory general across eye-height?– Is the ART theory general across object orientation?

What is perspective?

• Leonardo– Perspective is nothing else than seeing a

place or objects behind a plane of glass, quite transparent, on the surface of which the objects behind the glass are to be drawn.

What is perspective?

from Taylor (1719)

What is perspective?What is perspective?

Why study perspective?

• Perspective is the basic geometry of the visual system– Determines the information available to the

visual system

Why study perspective pictures?

• Reason 1: explain picture perception• Since the Renaissance… paradoxes

concerning picture perception have plagued the consciousness of mankind

• Explanations by:– Leonardo da Vinci– Albert Einstein– other guys…– have all FAILED!!!

Reason 1: explain picture perception

Why study perspective pictures?

• Reason 1: explain picture perception

• Reason 2: explain spatial perception

Reason 2: explain spatial perception

• The assumption– There is nothing special about picture

perception– Picture Perception = Everyday Perception

• So, a theory that can account for picture perception will account for everyday perception as well

• But…– Why not just study Everyday Perception?


• Why not just study everyday perception?

• Newtonian Physics vs. Einstein’s Physics


• Why not just study everyday perception?• Everyday perception will give you a

“Newtonian Physics” theory of vision• Picture perception may give you an

“Einstein’s Physics” theory of vision– Why? Because you can put people in novel

situations– i.e., you can have the observer at the wrong

vantage point

The ART theory

Experiment 1

Experiment 1

Observer is:TOO FAR

Observer is:TOO CLOSE

Observer is:JUST RIGHT

Compressed (Average Response <90)

Perspective Constancy (Average Response 90-110)

Elongated (Average Response >110)

Observer is:TOO FAR

The ART theory

• The “Angles and Ratios Together” theory

• Angles– “Angle from the Normal”

• Ratios– Visual Angle ratios

• Together– Together

The ART theoryDD

OO

CC

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The ART theory: Angle from the Normal

DD

OO

CC

BBAA

The ART theory: Visual Angle Ratio (Side/Bottom)

DD

OO

CC

BBAA

The ART theory

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2

Angle from Normal (radians)

Vis

ual

An

gle

Rat

io

ElongatedCompressedSquare

0

0.5

1

1.5

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2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

ual

An

gle

Rat

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ElongatedCompressedSquare

The “ART Theory Ranges”

The ART theory

• Able to account for Experiment 1…

• Can it generalize to other situations?

• Like…

The ART theory

• Changes in observer position?

Experiment 1

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

ual

An

gle

Rat

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Sid

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ElongatedSquareCompressed

Experiment 2

0

0.5

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1.5

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2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Sid

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)


Experiments 1 & 2

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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l A

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Elongated 1

Square 1

Compressed 1

Elongated 2

Square 2

Compressed 2

The ART theory

• Changes in observer position?

YES

The ART theory

• Changes in eye-height?

High

Mid

Low

Experiment 3

0

0.5

1

1.5

2

2.5

3

0 0.2 0.4 0.6 0.8 1 1.2


Vis

ua

l An

gle

Ra

tio

(S

ide

/Bo

tto

m)


Experiments 1 & 2

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Elongated 1

Square 1

Compressed 1

Elongated 2

Square 2

Compressed 2

Experiments 1, 2, & 3

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0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Sid

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)


The ART theory

• Changes in eye-height?

YES

The ART theory

• Changes in orientation?

Experiments 1, 2, and 3 Experiment 4

Observer is:TOO FAR

Experiment 4

0

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0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Elongated

Square

Compressed

Experiments 1, 2, & 3

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Experiments 1, 2, 3, & 4

0

0.5

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1.5

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2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


Vis

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Elongated 1 Square 1 Compressed 1


Elongated 4d Square 4d Compressed 4d


0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0 0.2 0.4 0.6 0.8 1 1.2


The ART theory

• Changes in orientation?

Experiments 1, 2, and 3 Experiment 4

MAYBE

Conclusions

• The ART theory begins to explain some of the paradoxes of picture perception

• The ART theory can be applied to perception of the real world (i.e., “Everyday Perception”)

• May need to add factors to ART theory to deal with orientation

Thank you.

perspective!!! igor juricevic & john m. kennedy. outline basics of perspective –what is...

Documents

art theory slide

far slide

close slide

picture perception slide

right slide

kennedy slide

spatial perception slide

art theory ranges slide