Behavior Classification by Eigen-decomposition of Periodic Motions
Michael RudzskyMichael Rudzsky
Joint work with Roman Goldenberg, Ron Kimmel, Ehud Joint work with Roman Goldenberg, Ron Kimmel, Ehud Rivlin Rivlin
Computer Science Department Technion-Israel Institute of Technology
Geometric Image Processing Lab
Segmentation and Tracking
Active Contour
Fast Geodesic Active Contours AOS Level Sets Fast Marching
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CLdsCgCS
Goldenberg, Kimmel, Rivlin, Rudzsky,
IEEE T-IP 2001
Background
Background subtraction
dacyxDdacyxDdsCgCSCoutCin
CL 2
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yxDaveragec
yxDaveragec
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Chan, Vese, Active Contours without Edges, IEEE T-IP 2001
Paragios, Deriche, Geodesic Active Regions for Motion Estimation and Tracking, ICCV-99
Parameterization
n - number of frames in the training set 50x50 - normalized images M2500 x n - training samples matrix
MMT = U VT, the principle basis {Ui, i=1..k}
Distinguishing by static appearance
Image I written as a vector vI
Parameterized representationin basis B, p = BTvI
DTFS||p - vI||
Back-projection
Original 11 frame one period subsequence
Projection to the `dogs & cats’ basis and the DTFS values
Recognizing motions
{If, f=1..T} - one period, temporally aligned set of normalized object images
pf, f=1..T - projection of the image If onto the principal basis B of size k
One-period subsequence representationVector P of size kT - (pf, f=1..T)
If k = 20 and normalized duration of one-period is T=10, then P is of size 200.
Parameterized modeling
Ju, Black, Yacoob, Cardboard People, ICFG-96
Black, Yacoob, Parameterized Modeling and Recognition of Activities, ICCV-98
Star Skeleton
0
20
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60
80
100
120
1 35 69 103 137 171 205 239 273 307 341 375 409 443 477 511 545
0
20
40
60
80
100
120
1 35 69 103 137 171 205 239 273 307 341 375 409 443 477 511 545
Distance from the center of mass
After low pass filter
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