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Robotics Institute
Seminar, January 16
Time
and Place | Seminar Abstract | Speaker
Biography | Speaker Appointments
A ground surface based space perception in real and virtual environments
Bing
Wu
Department of Psychological & Brain Sciences
University of Louisville
Louisville, KY 40292
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Time and Place |
Mauldin Auditorium (NSH 1305)
Refreshments
Talk
With reference to a flat terrain, humans can
judge distance accurately up to about 20m an ability important for various
actions. Here we explored how this feat is achieved and what is information
provided for accurate distance perception. Subjects distance judgment was
examined in real, altered and virtual environments using perceptual tasks or
actions to assess the role of a variety of intrinsic and environmental depth
cues. We found: (1). The perception of direction is largely veridical
(direction constancy). A target in the dark was seen along its projection line
from the observer even if the perceived location was erroneous (Ooi et. al.,
2001). This highlights the role of the angular declination, or height in the
visual field, in distance judgment. (2). A continuous and
homogeneously-textured ground is critical for veridical distance perception.
Texture variations, gaps in the ground, or the partial occlusion of the ground
will lead to errors in judging distance (Sinai et al., 1998; Yarbrough et al.,
2002). The results underscore the notion that the ground is used as the
reference frame for coding objects locations. (3). Distance is underestimated
if an observers view is restricted to the local ground area about the target.
This suggests that accurate distance judgment relies on a process that takes in
information about the target as well as that faraway from it to build an
accurate ground surface representation. We thus propose the sequential surface
integration process (SSIP) model that a ground surface representation is formed
by sampling and combining information across space and time and the computation
starts from near space where rich depth cues can provide for a reliable initial
representation and then progressively extends to distant areas. Confirming
this, our results found that subjects could judge distance accurately by
scanning local patches of the ground from near to far, but not in the reverse
direction (Wu et al., 2003).
References
Sinai, M. J., Ooi T. L., He J. Z., (1998).
Terrain influences the accurate judgment of distance, Nature, 395, 497-500.
Ooi, T.L., Wu, B. & He, Z.J. (2001).
Distance determined by the angular declination below the horizon. Nature, 414,
197-200. Yarbrough, G. L., Wu, B., Wu, J., He, Z. J., & Ooi, T. L. (2002).
Judgments of object location behind an
obstacle depend on the particular information selected. Journal of Vision,
2(7), 625a, http://journalofvision.org/2/7/625/.
Wu, B., Ooi, T.L., & He Z.J. (2003).
Perceiving distance accurately by a directional process of integrating ground
information, Nature (In press).
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Speaker Biography |
Bing Wu is a Ph.D. student in Dept. of
Psychological & Brain Sciences at the Univ. of Louisville, majored in
Experimental Psychology. Prior to his arrival at the University of Louisville
in 1999, he received a B.A. in Biomedical Engineering from Huazhong University
of Technology & Sciences in 1994 and a M.S. degree in Neurobiology in 1997
from Shanghai Institute of Physiology, Chinese Academy of Sciences. Currently,
he is working with Dr. Zijiang He. His research area is human space perception.
More specifically, his research aims at understanding what information in the
environment enable people to judge distance accurately and how this feat is
achieved by the visual system. Bing Wu has five papers published or accepted,
including two in Nature.
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Related Material |
- Talk abstract (doc).
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Speaker Appointments |
For appointments, please contact George Stetten
The Robotics Institute is part of the School of Computer Science, Carnegie Mellon University.