Finding Action Tubes with a Sparse-to-Dense Framework
This addresses inefficiency and inadequate long-term information use in action detection for video analysis, though it appears incremental as it builds on existing methods with a novel efficiency improvement.
The paper tackles spatial-temporal action detection by proposing an efficient sparse-to-dense framework that generates action tube proposals in a single forward pass, achieving competitive results on benchmark datasets and being about 7.6 times more efficient than the nearest competitor.
The task of spatial-temporal action detection has attracted increasing attention among researchers. Existing dominant methods solve this problem by relying on short-term information and dense serial-wise detection on each individual frames or clips. Despite their effectiveness, these methods showed inadequate use of long-term information and are prone to inefficiency. In this paper, we propose for the first time, an efficient framework that generates action tube proposals from video streams with a single forward pass in a sparse-to-dense manner. There are two key characteristics in this framework: (1) Both long-term and short-term sampled information are explicitly utilized in our spatiotemporal network, (2) A new dynamic feature sampling module (DTS) is designed to effectively approximate the tube output while keeping the system tractable. We evaluate the efficacy of our model on the UCF101-24, JHMDB-21 and UCFSports benchmark datasets, achieving promising results that are competitive to state-of-the-art methods. The proposed sparse-to-dense strategy rendered our framework about 7.6 times more efficient than the nearest competitor.