RPMNet++:结合Copula去噪模块的双向注意力点云配准网络
RPMNet++: A Bidirectional Attention Point Cloud Registration Network Combining Copula Denoising
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摘要: 针对点云实际获取存在噪声干扰, 密度差异及遮挡等问题, 为了提高复杂场景, 非理想样本条件下的点云配准精度, 提出一种结合 Copula 去噪模块的双向注意力点云配准网络 RPMNet++. 首先构建 Copula 去噪模块, 以邻域数据点具有相似特征这一假设为基础, 通过卷积神经网络提取点云特征, 计算肯德尔相关系数 τ 和 Clayton Copula分布函数, 并保留正相关的内点, 滤除负相关的噪声点, 缓解噪声干扰导致的特征偏差, 参数估计误差和对应点关系误判等问题; 然后在双向注意力机制下尽显局部特征学习, 将双向注意力明确分为采样点到邻域点注意力和邻域点到中心点注意力 2 部分, 综合两者并结合邻域特征编码增强对采样点特征及其邻域空间相关性的学习, 以利于从去噪后稀疏的、 局部结构不完善的点云中有效地提取数据特征, 在保证邻域相关性特征完整的同时, 提高网络对点云数据局部细粒度特征的学习能力. 点云配准实验结果表明, 在 ModelNet40 数据集上, 与 RPM-Net 相比, RPMNet++对各向同性平均旋转误差和平移误差的提升效果显著, 分别在无噪声数据集, 噪声数据集和部分可见的噪声数据集上下降(0.026, 0.001), (0.267 0, 0.001 9)和(0.560, 0.007); 在斯坦福 3D 数据集上, 与 7 种跨源配准算法相比, RPMNet++均能达到最优, 并具有良好的泛化性能与应用价值.Abstract: A network called RPMNet++ has been proposed to improve the accuracy of point cloud registration in complex scenes and under non-ideal sample conditions, including noise interference, density inconsistency, and structur-al incompleteness or damage caused by occlusion. First, we construct the Copula denoising module. Based on the assumption that neighboring data points have similar features, we extract point cloud features using a con-volutional neural network. These features are then used to calculate the Kendall correlation coefficient τ and the Clayton Copula distribution function. Based on the calculation results, positively correlated inliers are retained while negatively correlated noise points are filtered out, thereby mitigating issues such as feature bias, parame-ter estimation errors, and misidentification of corresponding points due to noise interference. Second, local fea-ture learning is achieved under the bidirectional attention mechanism. Bidirectional attention is explicitly di-vided into two parts: attention from sampling points to neighboring points and attention from neighboring points to the central point. By combining these two components and incorporating neighborhood feature encoding, the learning of sampling point features and their spatial correlations in the neighborhood is enhanced. This facili-tates the effective extraction of data features from the denoised, sparse, and locally incomplete point cloud. This feature learning method ensures the integrity of neighborhood correlation features while improving the net-work’s ability to learn fine-grained local features of point cloud data. Point cloud registration experiments demonstrate that, compared to RPM-Net on the ModelNet40 dataset, RPMNet++ significantly reduces the iso-tropic average rotation error and translation error, with reductions of (0.026, 0.001), (0.267 0, 0.001 9), and (0.560, 0.007) on noise-free, noisy, and partially visible noisy datasets, respectively. On the Stanford 3D dataset, RPMNet++ outperforms seven cross-source registration algorithms, achieving optimal results and exhibiting good generalization performance and application value.