Triplet Online Instance Matching Loss for Person Re-identification

TL;DR

This paper introduces a Triplet Online Instance Matching (TOIM) loss that emphasizes hard samples, combines advantages of existing loss functions, and accelerates convergence for person re-identification, validated on a new large-scale dataset.

Contribution

The paper proposes a novel TOIM loss function that improves person ReID accuracy and training efficiency by focusing on hard samples and simplifying batch construction.

Findings

TOIM outperforms baseline methods by up to 21.7% in accuracy.

The new loss function accelerates convergence compared to traditional methods.

Validation on multiple datasets demonstrates the effectiveness of TOIM.

Abstract

Mining the shared features of same identity in different scene, and the unique features of different identity in same scene, are most significant challenges in the field of person re-identification (ReID). Online Instance Matching (OIM) loss function and Triplet loss function are main methods for person ReID. Unfortunately, both of them have drawbacks. OIM loss treats all samples equally and puts no emphasis on hard samples. Triplet loss processes batch construction in a complicated and fussy way and converges slowly. For these problems, we propose a Triplet Online Instance Matching (TOIM) loss function, which lays emphasis on the hard samples and improves the accuracy of person ReID effectively. It combines the advantages of OIM loss and Triplet loss and simplifies the process of batch construction, which leads to a more rapid convergence. It can be trained on-line when handle the joint detection and identification task. To validate our loss function, we collect and annotate a large-scale benchmark dataset (UESTC-PR) based on images taken from surveillance cameras, which contains 499 identities and 60,437 images. We evaluated our proposed loss function on Duke, Marker-1501 and UESTC-PR using ResNet-50, and the result shows that our proposed loss function outperforms the baseline methods by a maximum of 21.7%, including Softmax loss, OIM loss and Triplet loss.