Dissecting Human Body Representations in Deep Networks Trained for Person Identification

Fuente: arXiv
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Autores principales: Metz, Thomas M, Hill, Matthew Q, Myers, Blake, Gandi, Veda Nandan, Chilakapati, Rahul, O'Toole, Alice J
Formato: Preprint
Publicado: 2025
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author Metz, Thomas M
Hill, Matthew Q
Myers, Blake
Gandi, Veda Nandan
Chilakapati, Rahul
O'Toole, Alice J
author_facet Metz, Thomas M
Hill, Matthew Q
Myers, Blake
Gandi, Veda Nandan
Chilakapati, Rahul
O'Toole, Alice J
contents Long-term body identification algorithms have emerged recently with the increased availability of high-quality training data. We seek to fill knowledge gaps about these models by analyzing body image embeddings from four body identification networks trained with 1.9 million images across 4,788 identities and 9 databases. By analyzing a diverse range of architectures (ViT, SWIN-ViT, CNN, and linguistically primed CNN), we first show that the face contributes to the accuracy of body identification algorithms and that these algorithms can identify faces to some extent -- with no explicit face training. Second, we show that representations (embeddings) generated by body identification algorithms encode information about gender, as well as image-based information including view (yaw) and even the dataset from which the image originated. Third, we demonstrate that identification accuracy can be improved without additional training by operating directly and selectively on the learned embedding space. Leveraging principal component analysis (PCA), identity comparisons were consistently more accurate in subspaces that eliminated dimensions that explained large amounts of variance. These three findings were surprisingly consistent across architectures and test datasets. This work represents the first analysis of body representations produced by long-term re-identification networks trained on challenging unconstrained datasets.
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id arxiv_https___arxiv_org_abs_2502_15934
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dissecting Human Body Representations in Deep Networks Trained for Person Identification
Metz, Thomas M
Hill, Matthew Q
Myers, Blake
Gandi, Veda Nandan
Chilakapati, Rahul
O'Toole, Alice J
Computer Vision and Pattern Recognition
Long-term body identification algorithms have emerged recently with the increased availability of high-quality training data. We seek to fill knowledge gaps about these models by analyzing body image embeddings from four body identification networks trained with 1.9 million images across 4,788 identities and 9 databases. By analyzing a diverse range of architectures (ViT, SWIN-ViT, CNN, and linguistically primed CNN), we first show that the face contributes to the accuracy of body identification algorithms and that these algorithms can identify faces to some extent -- with no explicit face training. Second, we show that representations (embeddings) generated by body identification algorithms encode information about gender, as well as image-based information including view (yaw) and even the dataset from which the image originated. Third, we demonstrate that identification accuracy can be improved without additional training by operating directly and selectively on the learned embedding space. Leveraging principal component analysis (PCA), identity comparisons were consistently more accurate in subspaces that eliminated dimensions that explained large amounts of variance. These three findings were surprisingly consistent across architectures and test datasets. This work represents the first analysis of body representations produced by long-term re-identification networks trained on challenging unconstrained datasets.
title Dissecting Human Body Representations in Deep Networks Trained for Person Identification
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2502.15934