Transcript Explicit Surface Remeshing V. Surazhsky and C. Gotsman

Remeshing for
FEM Analysis
of Viscous Objects
CPSC 524 Final Project
Tricia Pang, Kyle Porter, Josna Rao
January 8, 2008
Outline

Introduction

Dataset

Method
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Results
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Discussion
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Introduction

FEM analysis of viscous objects
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Useful for modeling food bolus on tongue in human oral cavity
Food bolus
Tongue surface
Screenshot from Artisynth Toolkit
Mark A. Nicosia. “Planar Finite
Element Modeling of Bolus
Containment in the Oral Cavity.”
Computers in Biology & Medicine,
2007.
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Introduction

Problems result from large physical deformations
Mark A. Nicosia. “Planar Finite Element Modeling of Bolus Containment in the Oral Cavity.”
Computers in Biology & Medicine, 2007.


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Triangle mesh uniformity disrupted
Poor distribution of physical properties (node mass/velocity)
Further deformation requires well-conditioned meshes
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Project Goal
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Remesh viscous model after high deformation
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User-defined level of detail (number of vertices)
Good triangle uniformity
Preserve geometry
Extension: execute topological changes when required
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Eg. Mesh splitting
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Dataset

Generate in Artisynth
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Java-based 3D biomechanical modelling toolkit
Physical simulation using FEM mechanics
Node connectivity described by tetrahedrons
Replicate high-viscosity by setting material property
Simulate physical deformations until failure
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Method
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Explicit surface remeshing (Surazhsky and Gotsman, 2003)
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2D remeshing using local parameterizations
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Adjust vertices to maximize angles of triangles in mesh
Use error metrics to ensure mesh fidelity
Reference current mesh to original mesh
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Method
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Adjust number of vertices

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Alternate between edge splits/collapses and area-based
remeshing
Area-based remeshing
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Local 2D parameterizations
Relocate vertices in current mesh
Improve angles of incident triangles for each neighbourhood
Measure error between new mesh and original mesh
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Delaunay edge flips
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Regularize connectivity
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Obtain ideal valence for each vertex
Angle-based smoothing
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Method
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Overlapping Parameterization
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Patch parameterization scheme for performing local operations
Patches stored and reused
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Method
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Extension: Mesh Splitting
 Execute when “bottleneck” occurs
 Method #1: Principal curvature
Kmin < 0
x
Kmax > 0
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Method #2: Medial axis
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No working implementation for project
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Results
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Results
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Discussion
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High triangle uniformity in final meshes
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Limitation of method:
 Sharp
 More
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features sometimes not preserved
fine-tuning of error metrics
Limited dataset
 Could
not reproduce highly-deformed meshes in
Artisynth because poor mesh quality results in
deformation failure
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References

V. Surazhsky and C. Gotsman. Explicit Surface Remeshing.
Eurographics Symposium on Geometry Processing, pages 17–28,
2003.

V. Surazhsky and C. Gotsman. High quality compatible
triangulations. Proceedings of 11th International Meshing
Roundtable, pages 183-192, Sept. 2002.
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S. Fels, F. Vogt, K. van den Doel, J. Lloyd, I. Stavness and E.
Vatikiotis-Bateson. Developing Physically-Based, Dynamic Vocal
Tract Models using ArtiSynth. Proc. Int. Seminar Speech
Production, pages 419-426, 2006.
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Questions?
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