behavior classification by eigen-decomposition of periodic motions michael rudzsky joint work with...
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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
Dynamism of a Dog on a Leash
Giacomo Balla, 1912
The Red Horseman
Carlo Carra, 1914
Muybridge Horse
Eadweard Muybridge, Animals in Motion, 1887
Horse - decomposition
Segmentation and Tracking
Active Contour
Fast Geodesic Active Contours AOS Level Sets Fast Marching
)(
0)(][
CLdsCgCS
Goldenberg, Kimmel, Rivlin, Rudzsky,
IEEE T-IP 2001
Tracking in color movies
Goldenberg, Kimmel, Rivlin, Rudzsky,
IEEE T-IP 2001
Background
Background subtraction
dacyxDdacyxDdsCgCSCoutCin
CL 2
)(22
2
)(11
)(
0),(),()(][
),(
),(
)(2
)(1
yxDaveragec
yxDaveragec
Coutside
Cinside
),(),(),( yxIyxByxD t
Chan, Vese, Active Contours without Edges, IEEE T-IP 2001
Paragios, Deriche, Geodesic Active Regions for Motion Estimation and Tracking, ICCV-99
Tracking
Tracking
Tracking
Information extraction
Walking man - periodicity
Walking cat -periodicity
Periodicity Analysis
t t+3 t+6 t+9
+3 +6 +9
Inter-frame correlation
Spatial Alignment
50x50
Temporal Scaling
Original period - 11 frames
Resampled period - 10 frames
Temporal Alignment
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.
Classification -dogs & cats
walk run gallop cat...
Classification -dogs & cats
Classification -people
walk run run45
Classification -people
Learning curves
Dogs and cats People
Parameterized modeling
Ju, Black, Yacoob, Cardboard People, ICFG-96
Black, Yacoob, Parameterized Modeling and Recognition of Activities, ICCV-98
Optical Flow
Polaba, Nelson, Recognizing Activities, ICPR-94
Motion History Images (MHI)
James W. Davis, OSU Motion Recognition Lab
Star Skeleton
0
20
40
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
Phase portrays
Shavit, Jepson, Motion Understanding from Qualitative Visual Dynamics, 1993
Summary
Segmentation active contours
Periodicity analysis global contour characteristics
Alignment spatial temporal
Parameterization Principal basis projection
Classification Nearest neighbors