DGC-Net: Dynamic Graph Contrastive Network for Video Object Detection

Video object detection is a challenging task in computer vision since it needs to handle the object appearance degradation problem that seldom occurs in the image domain. Off-the-shelf video object detection methods typically aggregate multi-frame features at one stroke to alleviate appearance degradation. However, these existing methods do not take supervision knowledge into consideration and thus still suffer from insufficient feature aggregation, resulting in the false detection problem. In this paper, we take a different perspective on feature aggregation, and propose a dynamic graph contrastive network (DGC-Net) for video object detection, including three improvements against existing methods. First, we design a frame-level graph contrastive module to aggregate frame features, enabling our DGC-Net to fully exploit discriminative contextual feature representations to facilitate video object detection. Second, we develop a proposal-level graph contrastive module to aggregate proposal features, making our DGC-Net sufficiently learn discriminative semantic feature representations. Third, we present a graph transformer to dynamically adjust the graph structure by pruning the useless nodes and edges, which contributes to improving accuracy and efficiency as it can eliminate the geometric-semantic ambiguity and reduce the graph scale. Furthermore, inherited from the framework of DGC-Net, we develop DGC-Net Lite to perform real-time video object detection with a much faster inference speed. Extensive experiments conducted on the ImageNet VID dataset demonstrate that our DGC-Net outperforms the performance of current state-of-the-art methods. Notably, our DGC-Net obtains 86.3%/87.3% mAP when using ResNet-101/ResNeXt-101.