CGCN: Context graph convolutional network for few-shot temporal action localization

Localizing human actions in videos has attracted extensive attention from industry and academia. Few-Shot Temporal Action Localization (FS-TAL) aims to detect human actions in untrimmed videos using a limited number of training samples. Existing FS-TAL methods usually ignore the semantic context between video snippets, making it difficult to detect actions during the query process. In this paper, we propose a novel FS-TAL method named Context Graph Convolutional Network (CGCN) which employs multi-scale graph convolution to aggregate semantic context between video snippets in addition to exploiting their temporal context. Specifically, CGCN constructs a graph for each scale of a video, where each video snippet is a node, and the relationships between the snippets are edges. There are three types of edges, namely sequence edges, intra-action edges, and inter-action edges. CGCN establishes sequence edges to enhance temporal expression. Intra-action edges utilize hyperbolic space to encapsulate context among video snippets within each action, while inter-action edges leverage Euclidean space to capture similar semantics between different actions. Through graph convolution on each scale, CGCN enables the acquisition of richer and context-aware video representations. Experiments demonstrate CGCN outperforms the second-best method by 4.5%/0.9% and 4.3%/0.9% mAP on the ActivityNet and THUMOS14 datasets in one-shot/five-shot scenarios, respectively, at [email protected]. The source code can be found in https://github.com/mugenggeng/CGCN.git.