Person Re-Identification with Discriminatively Trained Viewpoint Invariant Dictionaries

This paper introduces a new approach to address the person re-identification problem in cameras with non-overlapping fields of view. Unlike previous approaches that learn Mahalanobis-like distance metrics in some trans-formed feature space, we propose to learn a dictionary that is capable of discriminatively and sparsely encoding fea-tures representing different people. Our approach directly addresses two key challenges in person re-identification: viewpoint variations and discrim-inability. First, to tackle viewpoint and associated appear-ance changes, we learn a single dictionary to represent both gallery and probe images in the training phase. We then discriminatively train the dictionary by enforcing explicit constraints on the associated sparse representations of the feature vectors. In the testing phase, we re-identify a probe image by simply determining the gallery image that has the closest sparse representation to that of the probe image in the Euclidean sense. Extensive performance evaluations on three publicly available multi-shot re-identification datasets demonstrate the advantages of our algorithm over several state-of-the-art dictionary learning, temporal sequence matching, and spatial appearance and metric learning based techniques. 1