Modelling long-range dependencies is critical for scene understanding tasks in computer vision. Although convolution neural networks (CNNs) have excelled in many vision tasks, they are still limited in capturing long-range structured relationships as they typically consist of layers of local kernels. A fully-connected graph, such as the self-attention operation in Transformers, is beneficial for such modelling, however, its computational overhead is prohibitive. In this paper, we propose a dynamic graph message passing network, that significantly reduces the computational complexity compared to related works modelling a fully-connected graph. This is achieved by adaptively sampling nodes in the graph, conditioned on the input, for message passing. Based on the sampled nodes, we dynamically predict node-dependent filter weights and the affinity matrix for propagating information between them. This formulation allows us to design a self-attention module, and more importantly a new Transformer-based backbone network, that we use for both image classification pretraining, and for addressing various downstream tasks (object detection, instance and semantic segmentation). Using this model, we show significant improvements with respect to strong, state-of-the-art baselines on four different tasks. Our approach also outperforms fully-connected graphs while using substantially fewer floating-point operations and parameters. Code and models will be made publicly available at https://github.com/fudan-zvg/DGMN2

本论文提出了一种动态图消息传递网络，用于进行长程依赖性建模，以用于图像识别。该网络采用自适应抽样节点的方法，在传递信息时动态地预测节点相关过滤器权重和关联矩阵，以实现对自我注意机制的设计。研究结果表明，基于该模型的Transformer骨干网络在图像分类和物体检测等四种不同任务上，相对于现有的最先进技术，能够显著提升性能，同时性能优于完全连接的图并使用更少的浮点运算和参数。

动态图消息传递网络用于视觉识别