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DTSTART:20141026T030000
TZOFFSETFROM:+0200
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RDATE:20151025T030000
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BEGIN:DAYLIGHT
DTSTART:20150329T020000
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UID:calendar.7042.field_data.0@www.ugov-ricerca.uniroma1.it
DTSTAMP:20260404T184417Z
CREATED:20150505T141905Z
DESCRIPTION:Curvature\,  as a descriptor of shape (e.g. describing the boun
 dary of planar shapes) possesses a rare combination of good properties: It
  is intrinsic\, intuitive\, well defined\, extensively studied and of an u
 ndisputed perceptual importance. However\, there are at least two serious 
 problems concerning its such use in computer vision: One has to do with no
 ise. In a noisy curve\, having\, that is\, high frequency Fourier componen
 ts (hfFc) of no perceptual importance\, the local nature of curvature rest
 ricts it in describing the noise itself rather than the underlying shape. 
 Knowing whether hfFc of a curve represent noise or not\, would require sol
 ving the harder problem of recognizing the object. Since hfFc might be def
 ining for certain shapes or just noise in others\, their presence in unrec
 ognized (unknown) shapes is considered problematic\, albeit they may prese
 nt useful shape information. In practice\, they are usually eliminated fro
 m the boundary of all shapes\, by means of a blind step of smoothing\, at 
 the risk of losing useful discriminating shape information. Smoothing also
  distorts the shape's metrics in an unpredictable manner\, a highly undesi
 rable effect whenever certain 'morphometric' measurements are defining for
  classification. Another problem in relation to curvature as a descriptor 
 has to do with 'meaningfulness'. Even in noise free curves\, the local nat
 ure of curvature doesn't permit any kind of 'context' by means of which on
 e could differentiate between points of similar curvature with respect to 
 their perceptual characteristics on different parts of the curve. Behind b
 oth of these problems is curvature's local nature as It seems that any sol
 ution would have to defy the local definition of curvature.In this talk  t
 he local nature of curvature will be challenged at a theoretical level as 
 an attempt to address the above problems based on an alternative Global de
 finition of curvature will be discussed. The new concept of 'noising' (as 
 opposed to smoothing) emerges as a paradox and a new method for identifyin
 g vertices without even having to calculate curvature will be presented. E
 xperiments with smooth and noisy KIMIA and MPEG silhouettes and a comparis
 on to localized methods support the theoretical findings.
DTSTART;TZID=Europe/Paris:20150512T100000
DTEND;TZID=Europe/Paris:20150512T100000
LAST-MODIFIED:20150511T083631Z
LOCATION:Room B203
SUMMARY:Constantine Raftopoulos - Global Curvature and the Noising Paradox 
 for Vertex Localization in Unknown Shapes - Dr. Constantine Raftopoulos\, 
 NTUA Athens\, Greece
URL;TYPE=URI:http://www.ugov-ricerca.uniroma1.it/node/7042
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