Specular Reflections and the Perception of Shape

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Specular Reflections and the Perception of
Shape Roland W. Fleming, Antonio Torralba, Edward
H. Adelson Journal of Vision (2004)
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observation we are able to recover some depth
using only specular reflections problem how
is this accomplished? no traditional cues
available - motion - disparity -
texture - lambertian shading
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can we really recover depth from specularities?
Savarese, Li, Perona (2004) No, theyre only a
very weak cue.

• 3 objects
• - patch w/spec reflections
• - subjects try to guess original object in 3
  expts

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can we really recover depth from specularities?
Fleming, et al (2003, 2004) Yes, and reliably
and quite acccurately.

• stimuli irregular, smooth, w/boundaries
• subjects adjust randomly initialized normals to
  perceived orientation

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what information is available?
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what information is available? ...and we dont
rely on boundaries
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what information is available? a relationship
between curvature and reflection compression
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• we have to make some assumptions
• about the object
• about the surroundings

• texture compression can be computed quickly
  (though roughly) with filters
• using steerable pyramid
• 24 filter orientations at each location
• 1 scale very local

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• texture compression can be computed quickly
  (though roughly) with filters
• using steerable pyramid
• 24 filter orientations at each location
• 1 scale very local

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stable across different scenes
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stable across different scenes
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correspondence between truth and guesswork
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• how realistic are the stimuli?
• smoothness
• - limited world scenes
• specularity only

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orientation fields for shaded/specular objects
can be consistent
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...or very inconsistent
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so how do we disambiguate the two?
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• discussion
• claims
• simple, quick computations can give some
  information about depth
• evaluation
• subjects can perceive shape from specularity
  alone
• orientation field and its anisotropy correlate
  with curvature
• this is stable across scenes and varies
  shape-to-shape
• reflection-induced orientation fields are
  consistent/inconsistent with texture and
  shading
• implication
• fast, biologically relevant computation
• real world settings require parallel processing
  of shading/reflection
• whats missing
• priors on objects, world, inference, separation
  of reflection