Mesh Scissoring with Minima Rule and Part Salience

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Mesh Scissoring with Minima Rule and Part
Salience

• Yunjin Lee ,Seungyong Lee , Ariel
  Shamir,Daniel cohen-Or,
• Hans-Peter Seidel

Computer Aided Geometric Design, vol. 22, no. 5,
pp. 444-465, Elsevier Science, 2005 . (CAGD05).
CAGDCG
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Outline

• About Atuhor
• Definitions
• Related work
• Main Step
• Experimental Results
• Summary and Discussion

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About Author

• Yunjin Lee
• Post-Doc researcher
• Computer Graphics Lab.
• Dept. of Computer Sci. and Eng.,
  POSTECH
• Research Interests
• Mesh parameterization
• mesh segmentation
• mesh signal processing
• surface reconstruction
• non-photorealistic rendering.

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About Author

• Seungyong Lee
• Dept. of Computer Sci. and Eng., POSTECH
• Research Interests
• Computer Graphics
• Computer Animation
• Image Processing

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About Author

• Ariel Shamir
• Efi Arazi School of Computer Science
• The Interdisciplinary Center
• Research Interests
• Mesh Partitioning
• Skeleton Based Representations
• Multi-Resolution Models
• Object Feature-Space Analysis
• Digital Typography
• Visual Succinct Representation of Infor

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About Author

• Daniel Cohen-Or
• School of Computer Science, Tel
  Aviv University
• Research Interests
• Computer Graphics, in particular, rendering and
  modeling techniques
• Motion and Transformations
• Visibility Techniques
• Shapes and Surfaces
• Point-based Modeling

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About Author

• Hans-Peter Seidel

Head of the Computer Graphics Department
MPII for Computer Science, Saarbrücken

• Awarded the Leibniz Prize in 2003

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Definitions

• Mesh Scissoring
• Minima Rule
• Part Salience
• Feature Contour
• Geometric Snake

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Mesh Scissoring

• extracting sub-parts and pieces from exsting
  meshes
• part-type segmentation
• patch-type segmentation

A. Shamir, A formulation of boundary mesh
segmentation, in Proc.2nd International
Symposium on 3D Data Processing, Visualization,
and Transmission, 2004.
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Minima Rule

• defining a framework for how human perception
  might decompose an object into its constituent
  parts
• all negative minima of the principal curvatures
  (along their associated lines of curvature) form
  boundaries between parts

D. Hoffman, W. Richards, Parts of recognition,
Cognition 18 (1984) 6596.
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Part Salience

• the size relative to the whole object
• the degree to which it protrudes
• the strength of its boundaries.

figure-ground
D. Hoffman, M. Signh, Salience of visual parts,
Cognition 63 (1997) 2978.
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Geometric Snake

• external energy Emesh capturing capture nearby
  features
• internal energy Espline smoothing shape and
  shorten length

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Related Work

• growing regions
• merging regions

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Overview
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Feature Contour Extraction

• extracting feature contours on the mesh
• normalization of curvature values
• contour connection
• selecting a feature contour

normalized values assigned to the vertices of a
horse model
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Loop Completion

• completing the feature contour to a closed loop
• distance function
• normal function
• centricity function
• feature function

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Part Salience Test

• rejecting the loop if the conditions of part
  salience are not satisfied
• area summing the areas of triangles in the
  segment
• protrusion using a fitting plane obtained from
  the sample points on a contour
• featurepreventing high feature contours from
  being rejected by the protrusion test.

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Snake Movement

• evolving the snake to a loops final position
  for cutting

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Experimental Results
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Experimental Results
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Experimental Results
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Experimental Results
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Summary and Discussion

• working the best in a semi-automatic setting
• no global search for the best cut

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Thanks
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Growing Regions

• A. P. Mangan, R. T. Whitaker, Partitioning 3D
  surface meshes using watershed segmentation, IEEE
  Trans. Visualization and Computer Graphics 5 (4)
  (1999) 308321.
• A. D. Kalvin, R. H. Taylor, Superfaces Polygonal
  mesh simplification with bounded error, IEEE
  Computer Graphics and Applications 16 (3) (1996)
  6477.24
• O. Sorkine, D. Cohen-Or, R. Goldenthal, D.
  Lischinski, Bounded-distortion piecewise mesh
  parameterization, in Proc. IEEE Visualization
  2002, 2002, pp.355362.
• S. Shlafman, A. Tal, S. Katz, Metamorphosis of
  polyhedral surfaces using decomposition, Computer
  Graphics Forum (Proc. Eurographics 2002) 21
  (3)(2002) 219228.

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Merging Regions

• M. Garland, A. Willmott, P. Heckbert,
  Hierarchical face clustering on polygonal
  surfaces, in Proc. 2001 ACM Symposium on
  Interactive 3D Graphics, 2001, pp. 4958.
• T. DeRose, M. Kass, T. Truong, Subdivision
  surfaces in character animation, ACM Computer
  Graphics (Proc. of SIGGRAPH 98) (1998) 8594.
• O. D. Faugeras, M. Hebert, The representation,
  recognition, and positioning of 3-D shapes from
  range data, in T. Kanade (Ed.),
  Three-Dimensional Machine Vision, Kluwer Academic
  Publishers, 1987, pp. 301353.

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same thresholds different meshes
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Contour Connection
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Approximations
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Distance Function
measuring the distances from to other
vertices
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Normal Function
lower for normals that face opposite directions
of
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Centricity Function
being perpendicular to the medial axis of a mesh
shape.
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Feature Function
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Area
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Protrusion
blue planes are the fitting planes of contours
red points indicate the farthest points from the
planes
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Feature