Perceptual Science Series

3D Shape Perception: The Role of Priors

Dr. Zygmunt Pizlo

Monday, October 23, 2006, 01:00pm - 02:00pm

Purdue University, Department of Psychological Sciences and the School of Electrical and Computer Engineering

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The last 25 years of research on 3D shape perception have been dominated
by Marr's theory.  According to Marr, the visual system reconstructs the
visible surfaces first and then forms an object-centered representation of
the surfaces, called shape.  Surfaces are reconstructed by using depth
cues such as motion, binocular disparity, texture, etc.  I will present
results of several psychophysical experiments, which show that: (i) the
role of depth cues in establishing the 3D shape percept is minimal, (ii)
the perceived 3D shape cannot be predicted from perceived surfaces, and
(iii) the perceived shape depends on the operation of spatially global
constraints applied to the 2D shape on the retina.  These results were
used to formulate a new computational model of shape reconstruction.  The
model can accurately reconstruct 3D shapes without using depth cues.

Dr. Zygmunt Pizlo