Refinable Polycube G-Splines - University of Florida

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Refinable Polycube G-Splines Martin Sarov

¨ Peters Jorg

University of Florida

NSF CCF-0728797

M. Sarov, J. Peters (UF)

SMI 2016

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Background

Quest Surfaces with rational linear reparameterization = ‘as close as possible’ to regular splines

M. Sarov, J. Peters (UF)

SMI 2016

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Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

M. Sarov, J. Peters (UF)

SMI 2016

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Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

I

Simplest non-affine change of variables: rational linear q = p(ρ)

M. Sarov, J. Peters (UF)

SMI 2016

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Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

I

Simplest non-affine change of variables: rational linear q = p(ρ)

I

Implies linear scaling by ω:

p(t, 0) = q(0, t),

(

ω(t) ∂1 p (t, 0) = ∂2 p (t, 0) + ∂1 q (0, t), ω(t) := (1 − t)ω0 + tω1 ,

M. Sarov, J. Peters (UF)

SMI 2016

ω0 , ω1 ∈ R,

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Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

I

Simplest non-affine change of variables: rational linear q = p(ρ)

I

Implies linear scaling by ω:

p(t, 0) = q(0, t),

(

ω(t) ∂1 p (t, 0) = ∂2 p (t, 0) + ∂1 q (0, t), ω(t) := (1 − t)ω0 + tω1 , I

ω0 , ω1 ∈ R,

,: rational linear = closest to regular spline (ω = const) ,: maximizes the number of control handles

M. Sarov, J. Peters (UF)

SMI 2016

3 / 21

Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

I

Simplest non-affine change of variables: rational linear q = p(ρ)

I

Implies linear scaling by ω:

p(t, 0) = q(0, t),

(

ω(t) ∂1 p (t, 0) = ∂2 p (t, 0) + ∂1 q (0, t), ω(t) := (1 − t)ω0 + tω1 , I

I

ω0 , ω1 ∈ R,

,: rational linear = closest to regular spline (ω = const) ,: maximizes the number of control handles /: ω0 = ω1 or p(0, 0) and p(1, 0) have the same valence

M. Sarov, J. Peters (UF)

SMI 2016

3 / 21

Geometric Continuity I

Geometric Continuity G1 = C 1 continuity after change of variables

I

Simplest non-affine change of variables: rational linear q = p(ρ)

I

Implies linear scaling by ω:

p(t, 0) = q(0, t),

(

ω(t) ∂1 p (t, 0) = ∂2 p (t, 0) + ∂1 q (0, t), ω(t) := (1 − t)ω0 + tω1 , I

I

I

ω0 , ω1 ∈ R,

,: rational linear = closest to regular spline (ω = const) ,: maximizes the number of control handles /: ω0 = ω1 or p(0, 0) and p(1, 0) have the same valence [PS15]: valence restricted to 3, 6 M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

Outline

1

Polycube connectivity and control handles

2

Surface Construction

3

Multi-resolution

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

Restricted Connectivity: Polycube Configurations n ∈ {3, 4, 5, 6}:

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

2x2 split: Control Handles ci

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

2x2 split: Control Handles ci

Control handles ci ´ Boundary points bi (Bezier)

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

2x2 split: Control Handles ci

Edge Recovery: ci →bi

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

2x2 split: Control Handles ci

Edge Recovery: ci →bi smooth ?

M. Sarov, J. Peters (UF)

SMI 2016

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Polycube connectivity and control handles

2x2 split: Control Handles ci

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

Outline

1

Polycube connectivity and control handles

2

Surface Construction

3

Multi-resolution

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I

G1 constraints on BB-coefficients (technical)

.

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I I

G1 constraints on BB-coefficients Apparent valence (mimic 3–6)

α+1,11 2cp bα,11 + bα−1,11 , 10 = b10 10

cp := cos

2π . p

.

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I I I

G1 constraints on BB-coefficients Apparent valence Assign labels: hn, mi edge

.

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I I I I

G1 constraints on BB-coefficients Apparent valence Assign labels: hn, mi edge Simple G1 constraints work for n, m ∈ {3, 4, 5, 6} except hn, 4i, h4, mi with n 6= m.

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I I I I

I

G1 constraints on BB-coefficients Apparent valence Assign labels: hn, mi edge Simple G1 constraints work for n, m ∈ {3, 4, 5, 6} except hn, 4i, h4, mi with n 6= m. Construction steps:

.

M. Sarov, J. Peters (UF)

SMI 2016

11 / 21

Surface Construction

PGS: G1 construction for vertex valences 3, 4, 5, 6 I I I I

G1 constraints on BB-coefficients Apparent valence Assign labels: hn, mi edge Simple G1 constraints work for n, m ∈ {3, 4, 5, 6} except hn, 4i, h4, mi with n 6= m.

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

Smooth PGS surfaces

M. Sarov, J. Peters (UF)

SMI 2016

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Surface Construction

Smooth PGS surfaces

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Outline

1

Polycube connectivity and control handles

2

Surface Construction

3

Multi-resolution

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Multi-resolution of Polycube G1 -splines

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles?

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I

/: [PS15] add (refined) surfaces

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net /: C 1 bicubic spline refinement: depends on bi

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net /: C 1 bicubic spline refinement: depends on bi ,: if ci is set by PGS (= satisfies G1) then ci is unchanged by Edge Recovery + PGS.

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net /: C 1 bicubic spline refinement: depends on bi ,: if ci is set by PGS (= satisfies G1) then ci is unchanged by Edge Recovery + PGS.

I

de Casteljau preserves G1 of finer ci

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net /: C 1 bicubic spline refinement: depends on bi ,: if ci is set by PGS (= satisfies G1) then ci is unchanged by Edge Recovery + PGS.

I

de Casteljau preserves G1 of finer ci

Edge Recovery + PGS =⇒ same surface

M. Sarov, J. Peters (UF)

SMI 2016

16 / 21

Multi-resolution

Multi-resolution of Polycube G1 -splines

I

How to refine the control handles? I I I I

/: [PS15] add (refined) surfaces /: Catmull-Clark on polycube quad net /: C 1 bicubic spline refinement: depends on bi ,: if ci is set by PGS (= satisfies G1) then ci is unchanged by Edge Recovery + PGS.

I

de Casteljau preserves G1 of finer ci

Edge Recovery + PGS =⇒ same surface perturb ci =⇒ different smooth surface

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Summary I

Smooth surface covering irregularities of valence n = 3, 4∗ , 5, 6 in a C 1 bi-3 spline surface

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

Summary I

Smooth surface covering irregularities of valence n = 3, 4∗ , 5, 6 in a C 1 bi-3 spline surface

I

Control Handles = as for C 1 bi-3 spline (larger support)

M. Sarov, J. Peters (UF)

SMI 2016

17 / 21

Multi-resolution

Summary I

Smooth surface covering irregularities of valence n = 3, 4∗ , 5, 6 in a C 1 bi-3 spline surface

I

Control Handles = as for C 1 bi-3 spline (larger support)

I

Refinable – reproduces surfaces at finer level

QUESTIONS ?

M. Sarov, J. Peters (UF)

SMI 2016

17 / 21

Multi-resolution

Summary I

Smooth surface covering irregularities of valence n = 3, 4∗ , 5, 6 in a C 1 bi-3 spline surface

I

Control Handles = as for C 1 bi-3 spline (larger support)

I

Refinable – reproduces surfaces at finer level

QUESTIONS ?

M. Sarov, J. Peters (UF)

SMI 2016

17 / 21

Multi-resolution

Multiresolution: algebraic challenge

I

Challenge: global system, ω(

,: additional constraint

k α;k,1 ) (−bα;k−1,1 + 2bα;k−1,1 − 2bα;k1 10 20 10 + b20 ) = 0. ` {z } 2 | C 2 boundary

/: large support of ci handles ,: decay fast

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

PGSER

M. Sarov, J. Peters (UF)

SMI 2016

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Multi-resolution

PGS: G1 construction for vertex valences 3, 4, 5, 6 I

G1 constraints on BB-coefficients: d X d X b(u, v) := bij Bid (u)Bjd (v), i=0 j=0

p01 + q10 = ω0 p10 + (2 − ω0 )p00 , p11 + q11 = ρ(ω0 , ω1 ),

(1)

p21 + q12 = σ (ω0 , ω1 ),

(3)

p31 + q13 = (2 + ω1 )p30 − ω1 p20 .  1 ρ (ω0 , ω1 ) := 2ω0 p20 − ω1 p00 + (6 − 2ω0 + ω1 )p10 3  1 σ (ω0 , ω1 ) := ω0 p30 − 2ω1 p10 + (6 − ω0 + 2ω1 )p20 . 3

(4)

M. Sarov, J. Peters (UF)

SMI 2016

(2)

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Multi-resolution

What goes wrong when hn, 4i, h4, mi with n 6= m?

M. Sarov, J. Peters (UF)

SMI 2016

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