A Comprehensive Study on Temporal Modeling for Online Action Detection
This work addresses the practical challenge of online action detection for video analysis, but it is incremental as it builds on existing methods through a comprehensive study and hybridization.
The paper tackles the problem of temporal modeling in online action detection by comprehensively studying four meta types of methods and presenting hybrid approaches, resulting in state-of-the-art performance with sizable margins on THUMOS-14 and TVSeries datasets.
Online action detection (OAD) is a practical yet challenging task, which has attracted increasing attention in recent years. A typical OAD system mainly consists of three modules: a frame-level feature extractor which is usually based on pre-trained deep Convolutional Neural Networks (CNNs), a temporal modeling module, and an action classifier. Among them, the temporal modeling module is crucial which aggregates discriminative information from historical and current features. Though many temporal modeling methods have been developed for OAD and other topics, their effects are lack of investigation on OAD fairly. This paper aims to provide a comprehensive study on temporal modeling for OAD including four meta types of temporal modeling methods, \ie temporal pooling, temporal convolution, recurrent neural networks, and temporal attention, and uncover some good practices to produce a state-of-the-art OAD system. Many of them are explored in OAD for the first time, and extensively evaluated with various hyper parameters. Furthermore, based on our comprehensive study, we present several hybrid temporal modeling methods, which outperform the recent state-of-the-art methods with sizable margins on THUMOS-14 and TVSeries.