Recently, arbitrary-scale point cloud upsampling mechanism became increasingly popular due to its efficiency and convenience for practical applications. To achieve this, most previous approaches formulate it as a problem of surface approximation and employ point-based networks to learn surface representations. However, learning surfaces from sparse point clouds is more challenging, and thus they often suffer from the low-fidelity geometry approximation. To address it, we propose an arbitrary-scale Point cloud Upsampling framework using Voxel-based Network (\textbf{PU-VoxelNet}). Thanks to the completeness and regularity inherited from the voxel representation, voxel-based networks are capable of providing predefined grid space to approximate 3D surface, and an arbitrary number of points can be reconstructed according to the predicted density distribution within each grid cell. However, we investigate the inaccurate grid sampling caused by imprecise density predictions. To address this issue, a density-guided grid resampling method is developed to generate high-fidelity points while effectively avoiding sampling outliers. Further, to improve the fine-grained details, we present an auxiliary training supervision to enforce the latent geometric consistency among local surface patches. Extensive experiments indicate the proposed approach outperforms the state-of-the-art approaches not only in terms of fixed upsampling rates but also for arbitrary-scale upsampling.

最近，基于点云的任意尺度上采样机制因其在实际应用中的效率和便利性而越来越受欢迎。为了解决从稀疏点云学习表面表示所面临的挑战，我们提出了一种使用基于体素网络的任意尺度点云上采样框架（PU-VoxelNet）。通过利用体素表达的完整性和规律性，体素网络能够提供预定义的网格空间来近似三维表面，并根据每个网格单元内的预测密度分布重建任意数量的点。进一步，为了改善细节，我们提供了一种辅助训练监督方法，以强制实现局部表面块之间的潜在几何一致性。广泛的实验证明，所提出的方法在固定上采样率和任意尺度上采样方面都优于现有技术。

基于体素网络的任意尺度点云上采样与隐式几何一致性学习