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An algorithm for triangulating multiple 3D pol M Zou, T Ju, N Carr Eurographics Symposium on Geometry Processi 2013 Who? Kundan Krishna1 From? When? 1Department of Computer Science & Engineering, IIT Kanpur E-mail: [email protected] 5 September, 2014

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Introduction Previous WorkNew workIs it really good?References Introduction What is triangulation? IIT Kanpur1

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Page 1: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

An algorithm for triangulating multiple 3D polygonsM Zou, T Ju, N CarrEurographics Symposium on Geometry Processing2013

Who? Kundan Krishna1

From?

When?

1Department of Computer Science & Engineering, IIT KanpurE-mail: [email protected]

5 September, 2014

Page 2: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Contents

Introduction

Previous Work

New work

Is it really good?

References

IIT Kanpur 0

Page 3: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

IIT Kanpur 1

Page 4: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

Generate a surface whose boundaries are given.

IIT Kanpur 1

Page 5: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

Generate a surface whose boundaries are given.

Boundary specified in the form of points of one or manypolygons.

IIT Kanpur 1

Page 6: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

Generate a surface whose boundaries are given.

Boundary specified in the form of points of one or manypolygons.

Topologically equivalent to a sphere with holes.

IIT Kanpur 1

Page 7: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

Generate a surface whose boundaries are given.

Boundary specified in the form of points of one or manypolygons.

Topologically equivalent to a sphere with holes.

IIT Kanpur 1

Page 8: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Introduction

What is triangulation?

Generate a surface whose boundaries are given.

Boundary specified in the form of points of one or manypolygons.

Topologically equivalent to a sphere with holes.

IIT Kanpur 1

Page 9: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

IIT Kanpur 2

Page 10: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

IIT Kanpur 2

Page 11: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

The metric can be based on individual triangles or pairsof them.

IIT Kanpur 2

Page 12: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

The metric can be based on individual triangles or pairsof them.

Eg. Individual metric : Minimize sum of areas oftriangle.

IIT Kanpur 2

Page 13: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

The metric can be based on individual triangles or pairsof them.

Eg. Individual metric : Minimize sum of areas oftriangle.

Eg. Shared metric : Minimize dihedral angle betweentriangles.

IIT Kanpur 2

Page 14: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

The metric can be based on individual triangles or pairsof them.

Eg. Individual metric : Minimize sum of areas oftriangle.

Eg. Shared metric : Minimize dihedral angle betweentriangles.First algorithm to give a provably optimal algorithmfor minimizing such metrics, for general polygons.

IIT Kanpur 2

Page 15: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

The algorithm aims to optimize a certain metric.

The metric can be based on individual triangles or pairsof them.

Eg. Individual metric : Minimize sum of areas oftriangle.

Eg. Shared metric : Minimize dihedral angle betweentriangles.First algorithm to give a provably optimal algorithmfor minimizing such metrics, for general polygons.

IIT Kanpur 2

Page 16: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

One polygon

IIT Kanpur 3

Page 17: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work

One polygon

One polygonVery well researched problem.Optimal algorithms known.

Is it really good? References

IIT Kanpur 3

Page 18: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work

One polygon

One polygonVery well researched problem.Optimal algorithms known.Delaunay triangulation

Is it really good? References

IIT Kanpur 3

Page 19: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work

One polygon

One polygonVery well researched problem.Optimal algorithms known.Delaunay triangulation

Is it really good? References

IIT Kanpur 3

Page 20: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work

One polygon

One polygonVery well researched problem.Optimal algorithms known.Delaunay triangulation

Is it really good? References

IIT Kanpur 3

Page 21: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

More than one polygons

Algorithm known only for parallel polygons.

IIT Kanpur 4

Page 22: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

More than one polygons

Algorithm known only for parallel polygons.

IIT Kanpur 4

Page 23: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

More than one polygons

Algorithm known only for parallel polygons.

IIT Kanpur 4

Page 24: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

IIT Kanpur 5

Page 25: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

Proposed algorithm which works for arbitrary number ofpolygons which are arbitrarily positioned in space.

IIT Kanpur 5

Page 26: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

Proposed algorithm which works for arbitrary number ofpolygons which are arbitrarily positioned in space.

The algorithm uses divide and conquer strategy tosuccesively triangulate smaller partitions of the set ofpolygon points.

IIT Kanpur 5

Page 27: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

Proposed algorithm which works for arbitrary number ofpolygons which are arbitrarily positioned in space.

The algorithm uses divide and conquer strategy tosuccesively triangulate smaller partitions of the set ofpolygon points.

Major Achievement

It avoids non-manifold edges, which are edges belongingto more than 2 triangles in the triangulation.

IIT Kanpur 5

Page 28: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

Proposed algorithm which works for arbitrary number ofpolygons which are arbitrarily positioned in space.

The algorithm uses divide and conquer strategy tosuccesively triangulate smaller partitions of the set ofpolygon points.

Major Achievement

It avoids non-manifold edges, which are edges belongingto more than 2 triangles in the triangulation.

IIT Kanpur 5

Page 29: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

New work

Proposed algorithm which works for arbitrary number ofpolygons which are arbitrarily positioned in space.

The algorithm uses divide and conquer strategy tosuccesively triangulate smaller partitions of the set ofpolygon points.

Major Achievement

It avoids non-manifold edges, which are edges belongingto more than 2 triangles in the triangulation.

IIT Kanpur 5

Page 30: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Shortcomings

IIT Kanpur 6

Page 31: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Shortcomings

The algorithm for optimization is a naive one which isexponential in the number of polygons.

IIT Kanpur 6

Page 32: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Shortcomings

The algorithm for optimization is a naive one which isexponential in the number of polygons.

Not scalable.

IIT Kanpur 6

Page 33: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Shortcomings

The algorithm for optimization is a naive one which isexponential in the number of polygons.

Not scalable.The paper proposes to reduce the running time by

considering a subset of triangles as possible candidatesin trianglulation. Turns out that Delaunay triangles cando the job, with only 1% of triangles lying outside theset of Delaunay triangles entered.

Reduces the running time, but no formal proof has beengiven.

IIT Kanpur 6

Page 34: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

Shortcomings

The algorithm for optimization is a naive one which isexponential in the number of polygons.

Not scalable.The paper proposes to reduce the running time by

considering a subset of triangles as possible candidatesin trianglulation. Turns out that Delaunay triangles cando the job, with only 1% of triangles lying outside theset of Delaunay triangles entered.

Reduces the running time, but no formal proof has beengiven.

IIT Kanpur 6

Page 35: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Introduction Previous Work New work Is it really good? References

References

An algorithm for triangulating multiple 3D polygons byM Zou, T Ju, N Carr Eurographics Symposium onGeometry Processing 2013.

Some images taken from Google Image Search, andsome fromhttp://www.cse.wustl.edu/ zoum/projects/TriMultPoly.

IIT Kanpur 7

Page 36: An algorithm for triangulating multiple 3D polygons M Zou, T Ju, N Carr Eurographics Symposium on Geometry…

Thanks to Sharbat for the LATEXtemplate