RealTime Cloth Simulation

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Real-Time Cloth Simulation

• Advisor??? ??
• ???

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outline

• Introduction
• Related work
• Idea
• Possible problem

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Introduction
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Introduction

• Why we need ?
• Challenges in cloth simulation
• Model
• Integrator
• Collision handling
• Goal
• Stable
• Fast
• Good visual result

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Related work

• Model
• Integrator
• (Collision Handling)

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Related work Modeling(1)

• Particle-based methods
• Breen 1992
• energy-based model
• Baraff, Witkin 1998

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Related work Modeling(2)

• Finite Element Model
• Olaf, Michael, and Wolfgang2003
• Not popular

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Related work Modeling(3)

• Discrete Models
• Ko, Choi 2002

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Related work Integrator(1)

• Explicit Integrations
• based on Taylor expansion of the previous
  equation
• Euler (1st order), Mid-point (2nd order),
  Runge-Kutta (4th order)
• Implicit Integrations
• These methods reformulate the previous equation
  into a system of equations.
• These methods are very stable but difficult to
  implement.

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Related work Integrator(2)

• Explicit Integrations
• Strong points
• low computational time
• easy to implement
• Weak points - small time
• step
• small spring constant
• over-elongation problem

A B C
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Related work Integrator(3)

• Explicit Integrations
• the over-elongation problem
• Position correction
• fails when too many collisions occur
• between cloth and other objects
• Velocity correction
• not physically correct

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Related work Integrator(4)

• Verlet integration
• Arnulph, Clemens, Volker 2003
• increases the stability

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Related work Integrator(5)

• Implicit Integrations
• Find matrix H to solve the v(n1)

because
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Related work Integrator(6)

• Implicit Integrations
• Strong points
• stable whatever the chosen time step
• high spring constants allowed
• Weak points
• storing a big matrix
• solving a linear system
• real-time execution difficult to obtain

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Related work Integrator(7)

• Implicit Integrations
• Desbrun 1999
• approximated the Hessian matrix
• Consider the angular momentum

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Related work other method(8)

• Force Propagation

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Related work other method(9)
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Idea
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Idea

• Motivation
• To generate more delicate cloth, we usually
  increase mesh complexity
• Also increase computational time
• In game design, how to provide feature-preserved
  cloth model in real-time

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Idea

• Cloth animation with adaptively
• refined meshes
• ACM International Conference
• Proceeding Series 2005

An efficient animation of wrinkled cloth with
approximate implicit integration The Visual
Computer Journal 2001
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Idea

• Proposed method
• Create fine cloth mesh at the beginning
• In each time step,
• instead of computing position of each vertex, we
  clustering all the vertices
• and interpolated positions of each vertex in the
  same cluster
• Adjust the degree of clustering

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Idea

• Goal
• Wish to generate fast and detail-preserved cloth
• Increase stability
• smooth the spring damping
• Correct compressed spring
• Control the variable at each frame rendering
• View-dependent
• Character priority

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Possible problem
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Possible problem

• in each simulation
• How to clustering, according to?
• Curvature
• How to interpolated?
• Sampling
• Performance
• The most important!

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• Question?