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1Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Feature-based methodsand shape retrieval problems
© Alexander & Michael Bronstein, 2006-2009© Michael Bronstein, 2010tosca.cs.technion.ac.il/book
048921 Advanced topics in visionProcessing and Analysis of Geometric Shapes
EE Technion, Spring 2010
2Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Structure
Local
Feature descriptors
Global
Metric
3Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Combining local and global structures
BBK 2008; Keriven, Torstensen 2009; Dubrovina, Kimmel 2010; Wang, B 2010
Pair-wise stress (global) Point-wise stress (local)
Local structure can be geometric or photometric
4Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Photometric stress
Thorstenstein & Keriven 2009
5Numerical Geometry of Non-Rigid Shapes Diffusion Geometry
Heat kernels, encore
Brownian motion on X starting at point x, measurable set C
probability of the Brownian motion to be in C at time t
Coifman, Lafon, Lee, Maggioni, Warner & Zucker 2005
Heat kernel represents transition probability
6Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Intrinsic descriptors
Sun, Ovsjanikov & Guibas 2009
Multiscale local shape descriptor (Heat kernel signature)
can be interpreted as probability of Brownian motion to return to
the same point after time (represents “stability” of the point)
Time (scale)
7Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Sun, Ovsjanikov & Guibas 2009for small t
Relation to curvature
8Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Heat kernel signature
Heat kernel signatures represented in RGB space
Sun, Ovsjanikov & Guibas 2009Ovsjanikov, BB & Guibas 2009
9Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Heat kernel descriptors
Invariant to isometric deformations Localized sensitivity
to topological noise
J. Sun, M. Ovsjanikov, L. Guibas, SGP 2009M. Ovsjanikov, BB, L. Guibas, 2009
10Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale invariance
Original shape Scaled by
HKS= HKS=
Not scale invariant!
11Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale-invariant heat kernel signature
B, Kokkinos CVPR 2010
Log scale-space
Scaling = shift and multiplicative
constant in HKS
log + d/d
Undo scaling
Fourier transformmagnitude
Undo shift
0 100 200 300-15
-10
-5
0
t0 100 200 300
-0.04
-0.03
-0.02
-0.01
0
t0 2 4 6 8 10 12 14 16 18 20
0
1
2
3
4
=2k/T
12Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale invariance
B, Kokkinos 2009
Heat Kernel Signature Scale-invariantHeat Kernel Signature
13Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bending invariance
B, Kokkinos CVPR 2010
Heat Kernel Signature Scale-invariantHeat Kernel Signature
14Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bending invariance
Wang, B 2010
Geodesic+HKS Diffusion+HKS Commute+SI-HKS
15Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Topology invariance
Geodesic+HKS Diffusion+HKS
Wang, B 2010
16Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale invariance
Wang, B 2010
Geodesic+HKS Commute+SI-HKS
17Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Invariance
Geodesic metric
Rigid Inelastic Topology
Diffusion metric
Scale
Wang, B 2010
Commute-timemetric
Heat kernelsignature (HKS)
Scale-invariant HKS (SI-HKS)
18Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
19Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Tagged shapes
Shapes withoutmetadata
Man, person, humanPersonText search
Content-based search
3D warehouse
20Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
?
Content-based search problems
Invariant shape retrievalShape classification
?
Semantic
Variability of shape
within category
Geometric
Variability of shape
under transformation
21Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Image vs shape retrieval
Illumination View Missing data
Deformation Topology Missing data
22Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bags of words
Notre Dame de Paris is a Gothic cathedral in the fourth quarter of Paris, France. It was the first Gothic architecture cathedral, and its construction spanned the Gothic period.
con
stru
ctio
nar
chit
ectu
reIt
aly
Fra
nce
cath
edra
lch
urc
hb
asili
caP
aris
Ro
me
Go
thic
Ro
man
St. Peter’s basilica is the largest church in world, located in Rome, Italy. As a work of architecture, it is regarded as the best building of its age in Italy.
Notre Dame de Paris is a Gothic cathedral in the fourth quarter of Paris, France. It was the first Gothic architecture cathedral, and its construction spanned the Gothic period.
St. Peter’s basilica is the largest church in world, located in Rome, Italy. As a work of architecture, it is regarded as the best building of its age in Italy.
23Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bags of features
Visual vocabulary
Feature detector + descriptor
Invariant to changes of the image
Discriminative (tells different images apart)
24Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Advantages
“Shape signature”
Easy to store
Easy to compare
Partial similarity possible
25Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Images vs shapes
Images Shapes
Many prominent features Few prominent features
Affine transforms, illumination,
occlusions, resolution
Non-rigid deformations, topology,
missing parts, triangulation
SIFT, SURF, MSER, DAISY, … Curvature, conformal factor,
local distance histograms
26Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
“ShapeGoogle”
Feature descriptor
Geometric words
Bag of words
Geometric expressions
Spatially-sensitive bag of features
“ ”
“ ”
27Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Geometric vocabulary
M. Ovsjanikov, BB, L. Guibas, 2009
28Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bags of features
Geometric vocabulary
M. Ovsjanikov, BB, L. Guibas, 2009
Nearest neighbor in the descriptor space
29Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bags of features
Geometric vocabulary
M. Ovsjanikov, BB, L. Guibas, 2009
Weighted distance to words
in the vocabulary
30Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Bags of features
Shape distance = distance between bags of features
M. Ovsjanikov, BB, L. Guibas, 2009
Statistics of different geometric words over the entire shape
31Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Index in vocabulary1 64
M. Ovsjanikov, BB, L. Guibas, 2009
Bags of features
32Michael Bronstein Shape Google: geometric words and expressions for invariant shape retrieval
Statistical weighting
Query q Database D
syzygy in astronomy means alignment of three bodies of the solar system along a straight or nearly straight line. a planet is in syzygy with the earth and sun when it is in opposition or conjunction. the moon is in syzygy with the earth and sun when it is new or full.
syzygy in astronomy means alignment of three bodies of the solar system along a straight or nearly straight line. a planet is in syzygy with the earth and sun when it is in opposition or conjunction. the moon is in syzygy with the earth and sun when it is new or full.
Sivic & Zisserman 2003BB, Carmon & Kimmel 2009
Frequent in document = important
in is
or
syzygy
Rare in database = discriminative
with
a
of
the
and when
33Michael Bronstein Shape Google: geometric words and expressions for invariant shape retrieval
Statistical weighting
Query q Database D
Significance of a term t
Term frequency Inverse documentfrequency
Weight bags of features by tf-idf
Reduce the influence of non-important terms in dense descriptor
Sivic & Zisserman 2003BB, Carmon & Kimmel 2009
34Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Expressions
In math science, matrix decomposition is a factorization of a matrix into some canonical form. Each type of decomposition is used in a particular problem.
In biological science, decomposition is the process of organisms to break down into simpler form of matter. Usually, decomposition occurs after death.
Matrix is a science fiction movie released in 1999. Matrix refers to a simulated reality created by machines in order to subdue the human population.
mat
rix
dec
om
po
siti
on
mat
rix
fact
ori
zati
on
scie
nce
fic
tio
nca
no
nic
al f
orm
In math science, matrix decomposition is a factorization of a matrix into some canonical form. Each type of decomposition is used in a particular problem.
In biological science, decomposition is the process of organisms to break down into simpler form of matter. Usually, decomposition occurs after death.
Matrix is a science fiction movie released in 1999. Matrix refers to a simulated reality created by machines in order to subdue the human population.
mat
rix
dec
om
po
siti
on is a
the of in to by
scie
nce
form
In math science, matrix decomposition is a factorization of a matrix into some canonical form. Each type of decomposition is used in a particular problem.
Matrix is a science fiction movie released in 1999. Matrix refers to a simulated reality created by machines in order to subdue the human population.
M. Ovsjanikov, BB, L. Guibas, 2009
35Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Expressions
In math science, matrix decomposition is a factorization of a matrix into some canonical form. Each type of decomposition is used in a particular problem.
mat
rix
dec
om
po
siti
on is a
the of in to by
scie
nce
form
In particular matrix used type a some science, decomposition form a factorization of is canonical. matrix math decomposition is in a Each problem. into of
mat
rix
dec
om
po
siti
on
mat
rix
fact
ori
zati
on
scie
nce
fic
tio
nca
no
nic
al f
orm
M. Ovsjanikov, BB, L. Guibas, 2009
36Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Visual expressions
“Inquisitor King” Inquisitor, King “King Inquisitor”
Giuseppe Verdi, Don Carlo, Metropolitan Opera
37Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Geometric expressions
M. Ovsjanikov, BB, L. Guibas, 2009
“Yellow Yellow”Yellow
No total order between points (only “far” and “near”)
Geometric expression = a pair of spatially close geometric words
38Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Spatially-sensitive bags of features
M. Ovsjanikov, BB, L. Guibas, 2009
is the probability
to find word at point and
word at point
Proximity between
points and
Distribution of pairs of geometric words
Shape distance
is the statistic of geometric expressions of the form
39Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
M. Ovsjanikov, BB, L. Guibas, 2009
Spatially-sensitive bags of features
40Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
SHREC 2010 dataset
41Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
SHREC 2010 datasetBB et al, 3DOR 2010
42Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
ShapeGoogle with HKS descriptor (mAP %)BB et al, 3DOR 2010
43Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
ShapeGoogle with SI-HKS descriptor (mAP %)BB et al, 3DOR 2010
44Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale 0.7 Heat Kernel Signature
?
Scale-Invariant Heat Kernel Signature
Scale-invariant retrieval
Kokkinos, B 2009
45Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Scale 1.3 Heat Kernel Signature
Scale-Invariant Heat Kernel Signature
Kokkinos, B 2009
Scale-invariant retrieval
46Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Heat Kernel SignatureLocalscale
Scale-Invariant Heat Kernel Signature
Kokkinos, B 2009
Scale-invariant retrieval
47Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Structure
Local
Feature descriptors
Global
Metric
48Michael Bronstein Diffusion geometry for shape recognition
Beylkin & Niyogi 2003Coifman, Lafon, Lee, Maggioni, Warner & Zucker 2005Rustamov 2007
Laplacian embedding
Represent the shape using finite-dimensional Laplacian eigenmap
Ambiguities!
49Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Osada, Funkhouser, Chazelle & Dobkin 2002Rustamov 2007
Global point signature (GPS) embedding
Deformation- and scale-invariant
No ambiguities related to eigenfunction permutations and sign
No need to compare multidimensional embeddings
Represent the shape using distribution of Euclidean distances in the
Laplacian embedding space (=commute time distances)
0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45
50Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Diffusion distance distributions
Mahmoudi & Sapiro 2009
Represent the shape using distribution of diffusion distances
Deformation-invariant How to select the scale?
0.5 1 1.5 2 2.5 3 3.5 x 10-3
51Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Spectral shape distance
Kernel Distance Distribution Dissimilarity
Aggregation
BB 2010
52Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Spectral shape distance
Kernel Distance Distribution DissimilarityAggregation
BB 2010
53Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Spectral shape distance
Kernel Distance Distribution DissimilarityAggregation
Diffusion distance
BB 2010
54Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Particular case I: Rustamov GPS embedding
Kernel Distance Distribution DissimilarityAggregation
BB 2010
55Numerical Geometry of Non-Rigid Shapes Feature-based methods & shape retrieval problems
Particular case II: Mahmoudi&Sapiro
Kernel Distance Distribution DissimilarityAggregation
BB 2010