Transductive semi-supervised metric learning for person re-identification

•We propose the Transductive Semi-Supervised Metric Learning (TSSML) framework to solve the open-set semi-supervised ReID problem.•We propose a graph-based transductive hard mining method for deeply mining hard pairwise relationships and a degree-based relationship confidence scoring method for reducing the negative effect of incorrect pairwise relationships.•We investigate the feature consistency loss to improve the robustness of the model and adopt the curriculum learning strategy to have a better optimization process.