We propose an octree guided neural network architecture and spherical convolutional kernel for machine learning from arbitrary 3D point clouds. The network architecture capitalizes on the sparse nature of irregular point clouds, and hierarchically coarsens the data representation with space partitioning. At the same time, the proposed spherical kernels systematically quantize point neighborhoods to identify local geometric structures in the data, while maintaining the properties of translation-invariance and asymmetry. We specify spherical kernels with the help of network neurons that in turn are associated with spatial locations. We exploit this association to avert dynamic kernel generation during network training that enables efficient learning with high resolution point clouds. The effectiveness of the proposed technique is established on the benchmark tasks of 3D object classification and segmentation, achieving new state-of-the-art on ShapeNet and RueMonge2014 datasets.

本文提出了一种基于八叉树引导的神经网络结构和球形卷积核来进行任意3D点云的机器学习。该网络架构充分利用了不规则点云的稀疏性，并通过空间划分分层粗化数据表示。同时，该提议的球形核有系统地量化点邻域，以识别数据中的局部几何结构，同时保持平移不变性和不对称性。我们利用与空间位置相关联的网络神经元来指定球形核，从而避免了网络训练期间动态核生成，以实现高分辨率点云的高效学习，并在3D对象分类和分割的基准任务上取得了新的最先进状态，分别在ShapeNet和RueMonge2014数据集上。

基于球形卷积核的八叉树引导的3D点云CNN