Rotation-Invariant Local-to-Global Representation Learning for 3D Point Cloud

We propose a local-to-global representation learning algorithm for 3D point cloud data, which is appropriate to handle various geometric transformations, especially rotation, without explicit data augmentation with respect to the transformations. Our model takes advantage of multi-level abstraction based on graph convolutional neural networks, which constructs a descriptor hierarchy to encode rotation-invariant shape information of an input object in a bottom-up manner. The descriptors in each level are obtained from neural networks based on graphs via stochastic sampling of 3D points, which is effective to make the learned representations robust to the variations of input data. The proposed algorithm presents the state-of-the-art performance on the rotation-augmented 3D object recognition benchmarks and we further analyze its characteristics through comprehensive ablative experiments.