Multiple Temporal Pooling Mechanisms for Weakly Supervised Temporal Action Localization

Recent action localization works learn in a weakly supervised manner to avoid the expensive cost of human labeling. Those works are mostly based on the Multiple Instance Learning framework, where temporal pooling is an indispensable part that usually relies on the guidance of snippet-level Class Activation Sequences (CAS). However, we observe that previous works only leverage a simple convolutional neural network for the generation of CAS, which ignores the weak discriminative foreground action segments and the background ones, and meanwhile, the relationship between different actions has not been considered. To solve this problem, we propose multiple temporal pooling mechanisms (MTP) for a more sufficient information utilization. Specifically, with the design of the Foreground Variance Branch, Dual Foreground Attention Branch and Hybrid Attention Fine-tuning Branch, MTP can leverage more effective information from different aspects and generate different CASs to guide the learning of temporal pooling. Moreover, different loss functions are designed for a better optimization of individual branches, aiming to effectively distinguish the action from the background. Our method shows excellent results on the THUMOS14 and ActivityNet1.2 datasets.