全文链接：
https://arxiv.xilesou.top/abs/1905.00953
The source code is here.
Introduction
Major Challenges
As an instance-level recognition problem, person ReID faces two major challenges as illustrated in Figure 1 :
The intra-class (instance/identity) variations are typically big due to the changes of camera viewing conditions. - hard positives
Small inter-class variations - people in public space often wear similar clothes; from a distance as typically in surveillance videos, they can look incredibly similar. - hard negatives
Omni-Scale Featrue
To match people and distinguish them from impostors, features corresponding both small local regions and global whole body regions are important.
Looking at the global-scale features would narrow down the search to the true match (middle) and an impostor (right).
The local-scale features gives away the fact that the person on the right is an impostor. (For more challenging cases, more complicated and richer features that span multiple scales are required.)