Multiple-shot Person Re-identification via Riemannian Discriminative Learning

Person re-identification

Person re-identification, a task of recognizing pedestrian appearance in different time and locations captured with a multi-camera network without field of view overlap, has attracted wide interest in the field of surveillance. Applications in security, medical guardianship, tracking, and even online image retrieval on clothes demonstrate the great while growing significance of the problem.

Anonymous Camera workflow

We present a Riemannian discriminative learning framework for multiple-shot person re-identification, named Multiple-shot Riemannian Discriminative Learning (MRDL). Firstly, image regions are encoded into covariance matrices or a Gaussian extension as robust feature descriptors. Since these matrices lie on some specific Riemannian manifolds, we introduce a manifold averaging strategy to fuse the feature descriptors from multiple images for a holistic representation, and exploit Riemannian kernels to implicitly map the averaged matrices to a Reproducing Kernel Hilbert Space (RKHS), where conventional discriminative learning algorithms can be conducted. In particular, we apply kernel variants of two typical methods, i.e., the Linear Discriminant Analysis (LDA) and Metric Learning to Rank (MLR), to demonstrate the flexibility of the framework. Extensive experiments on five public datasets including i-LIDS, CAVIAR, PRID2011, CUHK01 and SPRD exhibit impressive improvements over existing multiple-shot re-identification methods as well as representative single-shot approaches.

The CMC (Cumulative Matching Characteristic) rank-1/5/10/20 accuracies on these datasets are listed below:
   rank-1    rank-5  rank-10   rank-20
 i-LIDS 0.5917  0.8167  0.8917  0.9583
 CAVIAR 0.5000  0.7600  0.9200  1.0000
 PRID2011  0.6050  0.8650  0.9200  0.9600
 CUHK01 0.4093  0.6629  0.7639  0.8433
 SPRD  0.5429  0.8871  1.0000 

The proposed MRDL is compared with the multi-shot community and representative single-shot approaches, which are listed in the chart below:
compare
Approach comparison chart on i-LIDS (IL), CAVIAR (CA), PRID2011 (PR) and CUHK01 (CU). A check mark denotes a certain method reported results on a corresponding dataset. These works are categorized into single-shot (Sin.) ones and multi-shot ones, which are further divided into closest point-based (CP), score voting-based (SV), set structure-based (SS) and signature-based (SG) groups.

And the CMC curves are:
CMC-iLIDS CMC-CAVIAR CMC-PRID2011 CMC-CUHK01 (from left to right: i-LIDS, CAVIAR, PRID2011, CUHK01)


The details can be found in our [paper]. You can also access the Matlab [code] (Google Drive, Baidu Disk) for reproduction and the [results] for comparison.