Transcript Resolving Surface Collisions through Intersection Contour

Resolving Surface Collisions
through
Intersection Contour Minimization
Pascal Volino
Nadia Magnenat-Thalmann
MIRALab, University of Geneva
SIGGRAPH 2006
Abstract
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Advanced methods are need for CD
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To recovery intersecting surfaces
Not rely on intersection regions
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More broader application
Much simpler to implement
Outline
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Introduction
Related Work
Description of the Method
Results
Conclusions
Introduction
Introduction
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Early CD for cloth are restricted for cloth and
volumes
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Methods for ensuring adequate constrains
are complex
Related Work
Related Work
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Not only prevent but also repair the
intersections
Common approach is to identify the “collision
regions” by Volino et al.[1995]
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Retain a constant orientation with detection
Impractical to implement
Related Work
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Simpler approaches
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preventing surface intersections to occur or
spread
Baraff et al [2003] use “flypapering”
Bridson et al [2003] preserve wrinkle patterns
Bridson et al [2002] the most comprehensive way
Related Work
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A major contribution by Baraff et al [2003]
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Global Intersection Analysis method
Track intersections by identifying closed contour
Establish orientation correspondence
Apply collision response method
Major restriction
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Necessity of closed
intersection contour
Related Work
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A major contribution by Baraff et al [2003]
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Global Intersection Analysis method
Track intersections by identifying closed contour
Establish orientation correspondence
Apply collision response method
Major restriction
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Necessity of closed
intersection contour
Goal
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To overcome these limitations
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Intersection region
Non-consist constrains
Impractical to implement
Minimizing the length of the intersections
contour
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Rather than spending time to identifying colliding
surface regions
Description of the
Method
Minimizing Edge-Polygon Intersections
Integration with Collision response
The local and the Global Scheme
Description of the Method
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Resolution scheme
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Define a collision scheme that induce a relative
displacement
So as to reduce the
length of the
intersection contour
disappearance
of the surface
intersection
Minimizing Edge-Polygon
Intersections
Minimizing Edge-Polygon
Intersections
The local and the Global
Scheme
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Sometimes not efficient
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if the contour is already quite
straight or the actions are the
largest on the region
Results
Some Test Examples
Performance and Limitations
Results
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Integrated in a cloth simulation engine
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Based on particle systems for accurate
representation
Broad-phase CD using AABB hierarchies
Collisions are detected through edge-polygon
intersections
Some Test Examples
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Untangling Cloth Surfaces
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Local scheme works poorly in this context
Between 0.4 and 0.2 sec per iteration
Some Test Examples
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Robustness Test
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Randomly ignoring 50% of all collisions detected
Local scheme is fairly efficient in this context
Some Test Examples
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The Ribbon Simulation
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80000 polygons of
the ribbon, took
roughly 3 to 30 sec
per iteration
Shear deformations
often break the
simulation
Some Test Examples
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Garment Simulation
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Several layers of cloth
Not always accurate
Performance and Limitations
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The number of edge-polygon intersections
remains very low
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Compared to the number of regular collisions
between mesh elements
Resolve intersections progressively along the
simulation is more efficient
Performance and Limitations
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In few configurations, the algorithm
converges to a local minimum
Combined with intersection region identify
Conclusions
Conclusions
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The method is general and not suffer from
the limitations of existing method
Simple to implement
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The local scheme only relies on a simple
geometrical computation
The global scheme efficiently solve very large
surface intersections
easily be combined with most usual
approaches for CD
Question?