Mesh Modelling With Curve Analogies

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Mesh Modelling With Curve Analogies

• Steve ZelinkaMichael Garland
• University of Illinois at Urbana-Champaign

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In a Nutshell
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Overview

• Motivation
• Related Work
• Details of our Approach
• Curve Selection
• Surface Transformation
• Results
• Future Work

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Motivation

• Reduce artistic skill required for modelling
• Solution Modelling by Analogy A
  A B ?
• Images Hertzmann et al 2001
• Curves Hertzmann et al 2002

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Mesh Analogies?

• User burden
• Unsolved technical issues
• 
  ?

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Related Work

• Geometric texture synthesis Bhat et al
  2004 Lagae et al 2004

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Related Work

• Common parameterizations Kraevoy and Sheffer
  2004 Schreiner et al 2004 Allen et al 2003
• Deformation transfer Sumner and Popovic 2004

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Related Work

• Multiresolution Signal Processing Guskov et al
  1999
• Cut and Paste Surface Editing Biermann et al
  2001

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Related Work

• Generative modelling Snyder 1992
• Wires Singh and Fiume 1998
• Poisson-based editing Yu et al 2004

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Related Work

• Teddy Igarashi et al 1999, 2001

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Approach Overview

• Select surface curves
• Transform surface curves with Curve Analogies
• Transform the surface
• 2D sketch-based manipulation
• Simple implementation

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Curve Selection

• Planar intersection curves
• Parallel or rotating slices

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Curve Selection

• Planar intersection curves
• Parallel or rotating slices
• Silhouette curves

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Generality Issues

• Features controlled only on and along curves
• Use orthogonal, intersecting sets of curves
• Multiple passes

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Curve Analogies

• User sketches unfiltered, filtered curves
• Identical parameterizations required
• System iteratively copies offsets to target

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Curve Analogies

• Joint neighbourhood matching
• Find best t with A(t) B(tcurr), A(t)
  B(tcurr)
• Neighbourhoods must be aligned before comparison

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Surface Transformation

• Similar to Wires
• Vertices near a curvetrack movement oftheir
  closest points onthe curve

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Surface Transformation

• Similar to Wires
• Vertices near a curvetrack movement oftheir
  closest points onthe curve
• Vertex movementinversely proportional to
  distance to curve

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Surface Transformation

• Similar to Wires
• Vertices near a curvetrack movement oftheir
  closest points onthe curve
• Vertex movementinversely proportional to
  distance to curve
• Parallel local frames

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Influence Radius

• Radius of influence of each curve can be varied
• Can also vary fall-off function

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Influence Radius

• Radius of influence of each curve can be varied
• Can also vary fall-off function

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Influence Radius

• Radius of influence of each curve can be varied
• Can also vary fall-off function

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Multiple Curves

• Vertices can be influencedby multiple curves
• Candidate position from each influencing curve
• Final position weighted average of candidates

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Results

• Curve Analogies
• Dominate compute time
• Can be difficult to control

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Results
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Results
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Results

• Harmonic fields Ni et al 2004

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Future Directions

• Better Curve Analogies
• Avoid orientation flipping usingsurface
  information
• Use intrinsic curveparameterization
  toaccelerate
• Spatial influencesnear intersections

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Future Directions
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Future Directions

• Poisson-based surface transformation
• Can we use Image Analogies similarly?

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Thanks

• Funded in part by a grant from the NSF
  (CCR-0086084)
• Software/source code at
• http//graphics.cs.uiuc.edu/zelinka