TBGA-Net: Trigonometric Bilinear Attention and Global-Aware Aggregation Network for Large-Scale 3D Point Cloud Segmentation

The unstructured, unordered and inherent irregular sampling properties presents difficulties for accurate and efficient realizing semantic segmentation of large-scale 3D point cloud. The complexity and the long-distance information exploitation are the key challenges for large-scale 3D point cloud semantic segmentation. Therefore, in order to efficiently exploit long-distance global information and improve the segmentation accuracy of point cloud data located at the edges of distinct categories, a novel Trigonometric Bilinear attention and Global-aware Aggregation network (TBGA-Net) is designed to integrate and supplement the local-global contextual features for large-scale point clouds segmentation. The proposed Global-aware Context Aggregation block (GCA) can implicitly excavate the global context for each 3D point by utilizing its surface-to-volume ratio of the neighborhood to the global point cloud. Furthermore, aim at refining local-global features, the Trigonometric Bilinear Attention block (TBA) utilizes trigonometric functions to embed the point cloud coordinates of local regions, and applies bilinear attention to realize feature enhancement for obtaining more discriminative local-global features. Additionally, we further designed a novel Dynamic-adjusting Cross-entropy Loss (DCLoss) to incorporate with TBGA-Net for addressing the issue of class imbalance in training data for large-scale 3D point cloud semantic segmentation. The experimental results on three 3D point cloud datasets demonstrates that the proposed algorithm indicates better segmentation accuracy especially for the point located at the boundary of the distinct categories.