Attentive Rotation Invariant Convolution for Point Cloud-based Large Scale Place Recognition

Autonomous Driving and Simultaneous Localization and Mapping(SLAM) are becoming increasingly important in real world, where point cloud-based large scale place recognition is the spike of them. Previous place recognition methods have achieved acceptable performances by regarding the task as a point cloud retrieval problem. However, all of them are suffered from a common defect: they can't handle the situation when the point clouds are rotated, which is common, e.g, when viewpoints or motorcycle types are changed. To tackle this issue, we propose an Attentive Rotation Invariant Convolution (ARIConv) in this paper. The ARIConv adopts three kind of Rotation Invariant Features (RIFs): Spherical Signals (SS), Individual-Local Rotation Invariant Features (ILRIF) and Group-Local Rotation Invariant features (GLRIF) in its structure to learn rotation invariant convolutional kernels, which are robust for learning rotation invariant point cloud features. What's more, to highlight pivotal RIFs, we inject an attentive module in ARIConv to give different RIFs different importance when learning kernels. Finally, utilizing ARIConv, we build a DenseNet-like network architecture to learn rotation-insensitive global descriptors used for retrieving. We experimentally demonstrate that our model can achieve state-of-the-art performance on large scale place recognition task when the point cloud scans are rotated and can achieve comparable results with most of existing methods on the original non-rotated datasets.