Semi-supervised distance metric learning for person re-identification

As a fundamental task in automated video surveillance, person re-identification, which has received increasing attention in recent years, aims to match people across non-overlapping camera views in a multi-camera surveillance system. It has been reported that KISS metric learning has been followed by most of the previous supervised work because of its state of the art performance for person re-identification on VIPeR dataset. However, given only a small number of labeled image pairs available for training, the matching model certainly suffers from unstable learning process and poor matching result. To address this serious practical issue, we proposed a novel semi-supervised KISS metric learning (SS-KISS) approach which makes use of unlabeled data to improve the re-identification performance by 1) combining both global and local information to select the most confident image pairs from the unlabeled data; 2) using an ensemble approach, which explores advantages of supervised and unsupervised learning by reconciling two matching models on which labeled and un-labeled data to an optimal one via smart weighting schema. Extensive experiments have been conducted on three datasets: VIPeR, ETHZ, and i-LiDS, experimental results demonstrate that our approach achieves a sound performance in the case of small amount of labeled data.