  The person re-identification task requires to robustly estimate visual
similarities between person images. However, existing person re-identification
models mostly estimate the similarities of different image pairs of probe and
gallery images independently while ignores the relationship information between
different probe-gallery pairs. As a result, the similarity estimation of some
hard samples might not be accurate. In this paper, we propose a novel deep
learning framework, named Similarity-Guided Graph Neural Network (SGGNN) to
overcome such limitations. Given a probe image and several gallery images,
SGGNN creates a graph to represent the pairwise relationships between
probe-gallery pairs (nodes) and utilizes such relationships to update the
probe-gallery relation features in an end-to-end manner. Accurate similarity
estimation can be achieved by using such updated probe-gallery relation
features for prediction. The input features for nodes on the graph are the
relation features of different probe-gallery image pairs. The probe-gallery
relation feature updating is then performed by the messages passing in SGGNN,
which takes other nodes' information into account for similarity estimation.
Different from conventional GNN approaches, SGGNN learns the edge weights with
rich labels of gallery instance pairs directly, which provides relation fusion
more precise information. The effectiveness of our proposed method is validated
on three public person re-identification datasets.
