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Multilinear Principal Component Analysis of Tensor Objects for Recognition. Haiping Lu , K.N. Plataniotis and A.N. Venetsanopoulos The Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto. Motivation. Real data in pattern recognition
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Multilinear Principal Component Analysis of Tensor Objects for Recognition Haiping Lu, K.N. Plataniotis and A.N. Venetsanopoulos The Edward S. Rogers Sr. Department of Electrical and Computer Engineering University of Toronto International Conference on Pattern Recognition, Hong Kong, August 2006
Motivation • Real data in pattern recognition • High-dimensional: dimensionality reduction • Multidimensional: tensors • PCA: reshape tensors into vectors • Multilinear algebra • 2DPCA, 3DPCA • Multifactor analysis • Objective: multilinear PCA for tensors International Conference on Pattern Recognition, Hong Kong, August 2006
Overview • MPCA: natural extension of PCA • Multilinear singular value & eigentensor • Input: higher-order tensors • Application: gait recognition • Sample data set: 4th-order tensor • Gait sample: half gait cycle (normalized) • Recognition: outperforms baseline algorithm International Conference on Pattern Recognition, Hong Kong, August 2006
Notations • Vector: lowercase boldface • Matrix: uppercase boldface • Tensor: calligraphic letter • n-mode product: • Scalar product: • Frobenius norm: • n-rank (n-mode vectors): International Conference on Pattern Recognition, Hong Kong, August 2006
Higher-order SVD • Subtensors of the core tensorS • All-orthogonality • Ordered based on • : unitary International Conference on Pattern Recognition, Hong Kong, August 2006
PCA with tensor notation • Basis vectors (PCs): columns of • PCA subspace: truncate • Projection to feature space: International Conference on Pattern Recognition, Hong Kong, August 2006
Multilinear PCA • Centered input tensor samples: • HOSVD: • Keep columns of • n-mode singular value: • Basis tensor (eigentensor): • Projection: • MPCA features: International Conference on Pattern Recognition, Hong Kong, August 2006
EigenTensorGait for recognition • Gait sample: half gait cycle (3rd-order) • To obtain samples: partition based on foreground pixels in silhouettes • Noise removal: best rank approximation • Temporal normalization: interpolation • Feature distance: sum of the absolute differences (equivalent to L1 norm) • Sequence matching: sum of min-dist International Conference on Pattern Recognition, Hong Kong, August 2006
Best rank approximation The original silhouettes Best rank-(10,10,3) approximation International Conference on Pattern Recognition, Hong Kong, August 2006
Experiments • Data: USF gait challenge data sets V.1.7 • Different conditions: surface, shoe, view • Sample size: 64x44x20 • Best results: • Performance measure: CMCs • Results: better overall recognition rate compared with baseline algorithm International Conference on Pattern Recognition, Hong Kong, August 2006
Identification performance International Conference on Pattern Recognition, Hong Kong, August 2006
MPCA CMC curves International Conference on Pattern Recognition, Hong Kong, August 2006
Conclusions • MPCA: multilinear extension of PCA • Application of MPCA: EigenTensorGait • Half gait cycles as gait samples • Best rank approximation to reduce noise • Temporal normalization by interpolation • Future works • MPCA to other problems • Other multilinear extensions International Conference on Pattern Recognition, Hong Kong, August 2006
Related work • Haiping Lu, K.N. Plataniotis and A.N. Venetsanopoulos, "Gait Recognition through MPCA plus LDA", in Proc. Biometrics Symposium 2006(BSYM 2006), Baltimore, US, September 2006. International Conference on Pattern Recognition, Hong Kong, August 2006
Contact Information Haiping Lu Email: haiping@dsp.toronto.edu Academic website: http://www.dsp.toronto.edu/~haiping/ International Conference on Pattern Recognition, Hong Kong, August 2006