TGPS: dynamic point cloud down-sampling of the dense point clouds for Terracotta Warrior fragments

The dense point clouds of Terracotta Warriors obtained by a 3D scanner have a lot of redundant data, which reduces the efficiency of the transmission and subsequent processing. Aiming at the problems that points generated by sampling methods cannot be learned through the network and are irrelevant to downstream tasks, an end-to-end specific task-driven and learnable down-sampling method named TGPS is proposed. First, the point-based Transformer unit is used to embed the features and the mapping function is used to extract the input point features to dynamically describe the global features. Then, the inner product of the global feature and each point feature is used to estimate the contribution of each point to the global feature. The contribution values are sorted by descending for different tasks, and the point features with high similarity to the global features are retained. To further learn rich local representation, combined with the graph convolution operation, the Dynamic Graph Attention Edge Convolution (DGA EConv) is proposed as a neighborhood graph for local feature aggregation. Finally, the networks for the downstream tasks of point cloud classification and reconstruction are presented. Experiments show that the method realizes the down-sampling under the guidance of the global features. The proposed TGPS-DGA-Net for point cloud classification has achieved the best accuracy on both the real-world Terracotta Warrior fragments and the public datasets.