Adaptive Knowledge Transfer for Weak-Shot Gait Recognition

Most works for cloth-changing gait recognition assume that the sequences of different clothes are accessible for each subject in the training set, which, however, is almost impossible for real applications. In practice, the collection of gait sequences is usually aided by person re-identification which is more likely to cluster the cloth-consistent sequences for a subject, and it is laborious to merge the cloth-changing clusters with the same identity. As a result, the training set is usually comprised of two subsets, i.e., a fully-annotated base set where the cloth-changing sequences are available for each subject, and a weakly-annotated wild set where the sequences of different clothes for a subject are assigned diverse labels. In this work, we formulate a problem named Weak-Shot Gait Recognition which seeks to learn discriminative features from the mixture of base set and wild set. Furthermore, we propose an effective method called Adaptive Knowledge Transfer to deal with the weak-shot issue. In particular, we define the knowledge as the ability to judge whether two sequences come from the same subject or not, and we take an adaptive way to mine the useful information from wild set. For the experimental study, we build three weak-shot benchmarks based on CASIA-B, Outdoor-Gait, and CASIA-E respectively. Extensive experiments show that our method can bring consistent improvement. For example, under the cloth-changing condition of on the weak-shot CASIA-B, our method exceeds a naïve baseline by 7.10%.