Point clouds acquired by 3D scanning devices are often sparse, noisy, and non-uniform, causing a loss of geometric features. To facilitate the usability of point clouds in downstream applications, given such input, we present a learning-based point upsampling method, i.e., iPUNet, which generates dense and uniform points at arbitrary ratios and better captures sharp features. To generate feature-aware points, we introduce cross fields that are aligned to sharp geometric features by self-supervision to guide point generation. Given cross field defined frames, we enable arbitrary ratio upsampling by learning at each input point a local parameterized surface. The learned surface consumes the neighboring points and 2D tangent plane coordinates as input, and maps onto a continuous surface in 3D where arbitrary ratios of output points can be sampled. To solve the non-uniformity of input points, on top of the cross field guided upsampling, we further introduce an iterative strategy that refines the point distribution by moving sparse points onto the desired continuous 3D surface in each iteration. Within only a few iterations, the sparse points are evenly distributed and their corresponding dense samples are more uniform and better capture geometric features. Through extensive evaluations on diverse scans of objects and scenes, we demonstrate that iPUNet is robust to handle noisy and non-uniformly distributed inputs, and outperforms state-of-the-art point cloud upsampling methods.

通过学习的点云上采样方法iPUNet，可以在任意比例下生成密集、均匀的点，更好地捕捉尖锐特征；通过引入与尖锐几何特征对齐的横向场，使得生成的点在特征感知方面更优秀；同时，在横向场引导的上采样基础上，通过迭代策略将稀疏点移动到期望的连续三维表面上，使得稀疏点均匀分布且对应的密集样本更加均匀，更加准确地捕捉几何特征。经过广泛的对象和场景扫描评估，证明iPUNet能够处理嘈杂和非均匀分布的输入，优于现有的点云上采样方法。

iPUNet: 迭代交叉场引导的点云上采样