Learning Group Activity Features Through Person Attribute Prediction
Authors: Chihiro Nakatani, Hiroaki Kawashima, Norimichi Ukita

This paper proposes Group Activity Feature (GAF) learning in which features of multi-person activity are learned as a compact latent vector. Unlike prior work in which the manual annotation of group activities is required for supervised learning our method learns the GAF through person attribute prediction without group activity annotations. By learning the whole network in an end-to-end manner so that the GAF is required for predicting the person attributes of people in a group the GAF is trained as the features of multi-person activity. As a person attribute we propose to use a person's action class and appearance features because the former is easy to annotate due to its simpleness and the latter requires no manual annotation. In addition we introduce a location-guided attribute prediction to disentangle the complex GAF for extracting the features of each target person properly. Various experimental results validate that our method outperforms SOTA methods quantitatively and qualitatively on two public datasets. Visualization of our GAF also demonstrates that our method learns the GAF representing fined-grained group activity classes. Code: https://github.com/chihina/GAFL-CVPR2024.