Michael Langer Heinrich BülthoffNEC Research Institute MPI for Biological

Cybernetics

Princeton, NJ Tübingen, Germany

Shape from Shading under diffuse lighting: does dark mean deep?

Presentation at the European Conference on Visual Perception, Oxford, U.K, August 1998

N(x) L

I(x) = N(x) L

SFS on a Sunny Day

I(x) = N(x) L

SFS on a Sunny Day

(x)

SFS on a Cloudy Day

(x) = angle of visible light source

I(x) (x)

N(x) L d L

SFS under Diffuse Lighting

SFS under Diffuse Lighting

Hill or Valley ?

Does Dark Means Deep?

SFS under Diffuse Lighting

local intensity maximum

Does Dark Means Deep?

intensity

depth+

+

_

_

correlatedanti-correlated

Height-Intensity Correlation

Correlated Condition

Anti-Correlated Condition

1. Grey Silhouette

2. Pair of Probes

3. Test: Which is higher ?

0

0.2

0.4

0.6

0.8

1

+ _

perc

ent c

orre

ctN=17

Correlation

Which is higher ?

Which is brighter ?

heightbrightness

+0

0.2

0.4

0.6

0.8

1pe

rcen

t cor

rect

_Correlation

N=10

Which is brighter ?

I(x) = (x)

I(x) = N(x) L d L(x)

(Langer and Zucker ‘93)

(Stewart and Langer ‘96)

Computational Modeling

0

0.2

0.4

0.6

0.8

1

+ - + - + - human LZ ‘93 SL ‘96

perc

ent c

orre

ct

Human - Models

Conclusion

“Dark-means-deep” cannot account for shape-from-shading perception under diffuse lighting.

Point source models are insufficient. Our visual system uses a more accurate

physical model which is based on the angle of the visible light source.