shape from shading under diffuse lighting: does dark mean deep?
DESCRIPTION
Michael Langer Heinrich Bülthoff NEC Research Institute MPI for Biological Cybernetics Princeton, NJ Tübingen, Germany. - PowerPoint PPT PresentationTRANSCRIPT
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.