What is a Poselet ? Poselets capture part of the pose from a given viewpoint [Bourdev & Malik, ICCV09]
Poselets Examples may differ visually but have common semantics [Bourdev & Malik, ICCV09]
Poselets But how are we going to create training examples of poselets?
How do we train a poselet for a given pose configuration?
Finding correspondences at training time Given part of a human pose How do we find a similar pose configuration in the training set?
We use keypoints to annotate the joints, eyes, nose, etc. of people Left Hip Left Shoulder Finding correspondences at training time
Residual Error Finding correspondences at training time
Training poselet classifiers Residual Error: 0.150.200.100.350.150.85 1. Given a seed patch 2. Find the closest patch for every other person 3. Sort them by residual error 4. Threshold them
Training poselet classifiers 1. Given a seed patch 2. Find the closest patch for every other person 3. Sort them by residual error 4. Threshold them 5. Use them as positive training examples to train a linear SVM with HOG features
Which poselets should we train? Choose thousands of random windows, generate poselet candidates, train linear SVMs Select a small set of poselets that are: –Individually effective –Complementary
Selecting a small set of complementary poselets
Features HOGs at two levels (~2K-4K features) –16 x 16 –32 x 32 Color Histograms in H,S,B (30 features) –10 bins for H, S and B Skin classifier output (3 features) –GMM with 5 components –Fraction of skin pixels –hands-skin, legs-skin, neck skin