9 Riemannian metrics <strong>of</strong> immersed <strong>curves</strong> 589.1 H 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599.2 H A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599.3 Conformal metrics . . . . . . . . . . . . . . . . . . . . . . . . . . 609.4 “Rigidified” norms . . . . . . . . . . . . . . . . . . . . . . . . . . 6010 Sobolev type Riemannian metrics 6010.1 Sobolev-type metrics . . . . . . . . . . . . . . . . . . . . . . . . . 6110.1.1 Related works . . . . . . . . . . . . . . . . . . . . . . . . . 6210.1.2 Properties <strong>of</strong> H j metrics . . . . . . . . . . . . . . . . . . . 6210.2 Mathematical properties . . . . . . . . . . . . . . . . . . . . . . 6210.3 Sobolev metrics <strong>in</strong> <strong>shape</strong> <strong>optimization</strong> . . . . . . . . . . . . . . . 6310.3.1 Smooth<strong>in</strong>g <strong>of</strong> gradients, coarse-to-f<strong>in</strong>e flow<strong>in</strong>g . . . . . . . 6510.3.2 Flow regularization . . . . . . . . . . . . . . . . . . . . . . 6610.4 ˜H j is faster than H j . . . . . . . . . . . . . . . . . . . . . . . . . 6710.5 Analysis <strong>and</strong> calculus <strong>of</strong> ˜H 1 gradients . . . . . . . . . . . . . . . 6810.6 Existence <strong>of</strong> gradient flows . . . . . . . . . . . . . . . . . . . . . . 7210.6.1 Lemmas <strong>and</strong> <strong>in</strong>equalities . . . . . . . . . . . . . . . . . . . 7310.6.2 Existence <strong>of</strong> flow for the centroid energy (2.9) . . . . . . . 7710.6.3 Existence <strong>of</strong> flow for geodesic active contour . . . . . . . . 8210.7 Regularization <strong>of</strong> energy vs regularization <strong>of</strong> flow/metric . . . . . 8310.7.1 Robustness w.r.to local m<strong>in</strong>ima due to noise . . . . . . . 8410.8 New <strong>shape</strong> <strong>optimization</strong> energies . . . . . . . . . . . . . . . . . . 8510.8.1 Average weighted length . . . . . . . . . . . . . . . . . . . 8510.8.2 New edge-based active contour models . . . . . . . . . . . 8610.9 New regularization methods . . . . . . . . . . . . . . . . . . . . . 8810.9.1 Elastic regularization . . . . . . . . . . . . . . . . . . . . . 8811 Mathematical properties <strong>of</strong> the Riemannian space <strong>of</strong> <strong>curves</strong> 8911.1 Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8911.2 Reparameterization to normal motion . . . . . . . . . . . . . . . 9011.3 The H 0 distance is degenerate . . . . . . . . . . . . . . . . . . . 9111.4 Existence <strong>of</strong> critical geodesics for H j . . . . . . . . . . . . . . . . 9211.5 Parameterization <strong>in</strong>variance . . . . . . . . . . . . . . . . . . . . . 9211.6 St<strong>and</strong>ard <strong>and</strong> geometric distance . . . . . . . . . . . . . . . . . . 9311.7 Horizontal <strong>and</strong> vertical space . . . . . . . . . . . . . . . . . . . . 9311.8 From curve-wise parameterization to homotopy-wise . . . . . . . . 9411.8.1 Horizontal G ⊥ as length m<strong>in</strong>imizer . . . . . . . . . . . . . 9611.9 A geometric gradient flow is horizontal . . . . . . . . . . . . . . . 9711.10Horizontality accord<strong>in</strong>g to H 0 . . . . . . . . . . . . . . . . . . . . 9711.11Horizontality accord<strong>in</strong>g to H j . . . . . . . . . . . . . . . . . . . . 9811.12Horizontality is for any group action . . . . . . . . . . . . . . . . 9811.13Momenta . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9911.13.1 Conservation <strong>of</strong> momenta . . . . . . . . . . . . . . . . . . 99104
IndexC 0 , 73, 78, 82C 1 , 24, 73, 78, 82C 1 curve, 3C 1 functional between Fréchet spaces,24C 2 regular <strong>curves</strong>, 6C ∞ (I → lR n ), 24C j (I → lR n ), 23C 1,1loc , 82D s , 5, 61H 0 , 14–19, 58–61, 88, 91alternative def<strong>in</strong>ition, 61, 62, 64,66–68, 83–86, 88Hψ 0, 60H j , 61H j (I → lR n ), 23L ∞ metric, 51M/Diff(S 1 ), 4, 5, 41, 89, 93, 98O c , 94S 1 , 3, 33δ 0 , 32, 70˙γ(v) := ∂ v γ(v), 28∂ s , 5Diff(S 1 ), 4, 27, 37, 38, 41, 89, 93Emb(S 1 , lR n ), 34, 34Imm(S 1 , lR n ), 34, 34, 38, 62, 89Imm f (S 1 , lR n ), 34, 34, 38˜H j , 61b A , 8c ′ (θ) := ∂ θ c(θ), 3, 5d g (x, y), 54i-th mode <strong>of</strong> pr<strong>in</strong>cipal variation, 10u A , 8G acts on M, 32abstract differentiablemanifold, 25action, 4, 28, 91<strong>of</strong> a group on a distance, 33<strong>of</strong> a group on a space, 32<strong>of</strong> a group on the space <strong>of</strong> <strong>curves</strong>,37<strong>of</strong> a group on the space <strong>of</strong> <strong>curves</strong>,<strong>and</strong> momenta, 100<strong>of</strong> path <strong>in</strong> a metric, 29active contour, 11–15, 18, 19, 59, 66,73, 82, 85, 86, 88, 90arc parameter, 5arc-parameterized convolutional kernel,64arithmetic mean, 9asymmetric, 22asymmetric distance, 20atlas, 25, 39average <strong>in</strong>tegral, 6average <strong>shape</strong>, 9, 42average weighted length, 16, 85, 86avg, 6B, see M/Diff(S 1 )balloon model, 87Banach space, 22, 23, 78C 0 , C 1 , 73, 78, 82boundary based energies, 12Cartan, 31Cauchy–Lipschitz theorem, 78, 82center <strong>of</strong> mass, 17, 68, 70, 80centroid, 17, 68, 80centroid energy, 17, 70, 73, 76, 77Chan-Vese, 12, 18, 83, 84change <strong>of</strong> coord<strong>in</strong>atespolar, 48chart, 26charts, 25classes <strong>of</strong> <strong>curves</strong>, 34(simplified def<strong>in</strong>itions), 3closed <strong>curves</strong>, 3Cohn-Vossen, 43Comparison pr<strong>in</strong>ciple, 15complete, 21, 23computer vision, 2, 5, 12, 37, 46, 90conformal metric, 58, 60consistent, 62cont<strong>in</strong>gent cone , 47105
- Page 1 and 2:
Metrics of curves in shape optimiza
- Page 3 and 4:
shape analysis where we study a fam
- Page 5 and 6:
• F (c) = F (c ◦ φ) for all cu
- Page 7 and 8:
κ > 0HNNHNHκ < 0Figure 1: Example
- Page 9 and 10:
In the case of planar curves c 1 ,
- Page 11 and 12:
(a) (b) (c) (d) (e)Figure 3: Segmen
- Page 13 and 14:
where φ may be chosen to beφ(x) =
- Page 15 and 16:
2.4.1 Example: geometric heat flowW
- Page 17 and 18:
2.4.5 Centroid energyWe will now pr
- Page 20 and 21:
shapes. Unfortunately, H 0 does not
- Page 22 and 23:
• If the second request is waived
- Page 24 and 25:
• The Fréchet space of smooth fu
- Page 26 and 27:
Since φ k are homeomorphisms, then
- Page 28 and 29:
3.6.1 Riemann metric, lengthDefinit
- Page 30 and 31:
Theorem 3.30 Suppose that M is a sm
- Page 32 and 33:
Example 3.38 Let M = C ∞ ([−1,
- Page 34 and 35:
• sometimes S 1 will be identifie
- Page 36 and 37:
The proof is by direct computation.
- Page 38 and 39:
The term preshape space is sometime
- Page 40 and 41:
5 Representation/embedding/quotient
- Page 42 and 43:
6.1.1 Length induced by a distanceI
- Page 44 and 45:
0101200000000000011111111111110000
- Page 46 and 47:
6.2.4 Applications in computer visi
- Page 48 and 49:
of a small ball from A. The motion
- Page 50 and 51:
CutΩ(The arrows represent the dist
- Page 52 and 53:
7.3 L 1 metric and Plateau problemI
- Page 54 and 55: Definition 8.3 (Flat curves) Let Z
- Page 56 and 57: Proof. Fix α 0 ∈ S \ Z. Let T =
- Page 58 and 59: 8.2.2 RepresentationThe Stiefel man
- Page 60 and 61: 9.3 Conformal metricsYezzi and Menn
- Page 62 and 63: 10.1.1 Related worksA family of met
- Page 64 and 65: Definition 10.7 (Convolution) A arc
- Page 66 and 67: and̂∇˜HjE(0) = ̂∇ H 0E(0),̂
- Page 68 and 69: and we simply integrate twice! More
- Page 70 and 71: Corollary 10.18 In particular, the
- Page 72 and 73: 10.6 Existence of gradient flowsWe
- Page 74 and 75: • The length functional (from C 1
- Page 76 and 77: We can eventually estimate the diff
- Page 78 and 79: 7.552.5-10 -7.5 -5 -2.5 2.5 5 7.5 1
- Page 80 and 81: By using (i) and (ii) from lemma 10
- Page 82 and 83: 10.6.3 Existence of flow for geodes
- Page 84 and 85: 10.7.1 Robustness w.r.to local mini
- Page 86 and 87: We already presented all the calcul
- Page 88 and 89: 10.9 New regularization methodsTypi
- Page 90 and 91: can be solved for k (this is not so
- Page 92 and 93: 2. Now• at t = 1/2 it achieves th
- Page 94 and 95: Definition 11.10 • The orbit is O
- Page 96 and 97: y eqn. (11.3), where the terms RHS
- Page 98 and 99: So Prop. 11.19 guarantees that the
- Page 100 and 101: Theorem 11.23 Suppose that the Riem
- Page 102 and 103: 2.2.3 Examples of geometric energy
- Page 106 and 107: contour continuation, 11convolution
- Page 108 and 109: normal vector, 6objective function,
- Page 110 and 111: References[1] Luigi Ambrosio, Giuse
- Page 112 and 113: [30] Serge Lang. Fundamentals of di
- Page 114 and 115: [57] Ganesh Sundaramoorthi, Anthony