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Guangqi Ye, Jason J. Corso, Gregory D. Hager Computational Interaction and Robotics Lab The Johns Hopkins University Baltimore, MD. Gesture Recognition Using 3D Appearance and Motion Features. Analogy Between Gesture and Speech. 4DT Platform.
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Guangqi Ye, Jason J. Corso, Gregory D. Hager Computational Interaction and Robotics Lab The Johns Hopkins University Baltimore, MD Gesture Recognition Using 3D Appearance and Motion Features
4DT Platform • Previous work: J. Corso, D. Burschka, G. Hager, The 4DT: Unencumbered HCI With VICs. CVPRHCI, 2003. • Geometrically and photometrically calibrated • Known background
Video Preprocessing Acquisition Rectification Color Calibration Background Subtraction
System Framework Image Preprocessing Coarse Stereo Matching Appearance/Motion Extraction Feature Clustering Gesture Recognition
Visual Feature Capturing: 3D Volume • Consider limited 3D space around object • Block-based coarse stereo matching
Motion Computation • Motion by differencing of stereo volume
Unsupervised Learning of Feature Set • VQ: K-means approach • Choice of cluster number based on distortion analysis
Temporal Gesture Modeling • 6-state discrete forward HMMs • Multilayer Neural Network Aligning all sequences to have equal length 3-layers, 50 hidden nodes
Experiment: Gesture Vocabulary Push Toggle
Gesture Vocabulary Swipe Left Swipe Right
Gesture Vocabulary Twist Clockwise Twist Anti-clockwise
Different Feature Data Sets • Appearance volume • 5x5x5=125 • 10x10x10=1000 • Motion volume • Concatenation of appearance and motione.g.,(125-appearance, 1000-d motion) • Combination of clustering result of appearance and motion • Form a 2-d vector of cluster identity e.g., (3, 2)
Gesture Recognition • Training: >100 sequences for each gesture • Test: >70 sequences for each gesture • Combination achieves best results
Conclusion • Novel approach to extract 3D appearance and motion cues without tracking • VQ clustering to learn gesteme • Modeling dynamic gestures using HMM, NN • Real-time implementation on 4DT • Extensive experiments achieve high recognition accuracy
3D Appearance Volume • Comprehensive color normalization • Coarse disparity map Consider local images of m x n patches, perform pair-wise image matching between patches • Disparity search range [0, ( p-1 ) * w ] • Dimensionality 3D volume m*n*p
Gesture Recognition • HMM modeling on collapsed sequencesRaw: 6 6 6 5 5 5 5 5 4 4 4 4 1 1Collapsed: 6 5 4 1 • Without considering duration
4DT Platform • Gestures in visual HCI: popular choice • Manipulative gesture modeling without tracking Difficulty of reliable tracking of hand Complexity of hand modeling • 3D data acquisitionLimitation of 2D cues for modeling handStereo matching Special sensors
Properties of 4DT • Known background & object properties