Multiple Biological Granularities Network for Person Re-Identification

The task of person re-identification is to retrieve images of a specific pedestrian among cross-camera person gallery captured in the wild. Previous approaches commonly concentrate on the whole person images and local pre-defined body parts, which are ineffective with diversity of person poses and occlusion. In order to alleviate the problem, researchers began to implement attention mechanisms to their model using local convolutions with limited fields. However, previous attention mechanisms focus on the local feature representations ignoring the exploration of global spatial relation knowledge. The global spatial relation knowledge contains clustering-like topological information which is helpful for overcoming the situation of diversity of person poses and occlusion. In this paper, we propose the Multiple Biological Granularities Network (MBGN) based on Global Spatial Relation Pixel Attention (GSRPA) taking the human body structure and global spatial relation pixels information into account. First, we design an adaptive adjustment algorithm (AABS) based on human body structure, which is complementary to our MBGN. Second, we propose a feature fusion strategy taking multiple biological granularities into account. Our strategy forces the model to learn diversity of person poses by balancing the local semantic human body parts and global spatial relations. Third, we propose the attention mechanism GSRPA. GSRPA enhances the weight of spatial relational pixels, which digs out the person topological information for overcoming occlusion problem. Extensive evaluations on the popular datasets Market-1501 and CUHK03 demonstrate the superiority of MBGN over the state-of-the-art methods.