EAAI Journal 2026 Journal Article
A Point-Voxel Transformer for point cloud object detection with spatial and channel attention
- Guangyu Ji
- Jun Lu
- Chengtao Cai
- Kaibin Qin
Voxelization loss has a significant impact on small object detection. However, existing point-voxel based two-stage object detection methods mainly generate three-dimensional (3D) proposal boxes using voxel features. The coarse representation of point clouds by voxels can result in difficulty in accurately capturing fine-grained features of small objects, and the accuracy of 3D bounding box regression may also be compromised, impacting detection accuracy. To solve this problem, we propose a novel voxel-point based architecture, named Point-Voxel Spatial-Channel Transformer (PVCST), to represent objects using point features. PVCST consists of two modules: the Voxel-based Spatial-Channel Attention module (VCSA) and the Point-based Spatial-Channel Attention module (PCSA). The VCSA employs channel attention to enhance sensitivity to local feature variations within a voxel and spatial attention to capture relationships among object parts across voxels, enabling the network to construct more comprehensive object representations. PCSA uses channel attention to adjust the importance of features, enhancing adaptability to varying dataset conditions, and spatial attention to identify critical regions, suppress noise, and capture long-range dependencies in the point cloud. By integrating spatial features and channel features, which are two distinct types of geometric information, VCSA and PCSA enhance object feature representation, particularly for small objects. Since point clouds of small objects tend to be sparse, a richer representation is especially crucial for their accurate detection. PVCST generates 3D proposal boxes directly from point-based features and directly utilizes original point features in these proposals for classification and regression, ensuring the integrity of the original input data without introducing additional points during the parallel computation of the Transformer. PVCST achieves mean Average Precision (mAP) scores of 78. 31% and 70. 66% on LEVEL 1 and LEVEL 2 of the vehicle category on the Waymo 3D detection benchmark.