Distribution-aware contrastive learning for domain adaptation in 3D LiDAR segmentation

Semantic segmentation of 3D LiDAR point clouds is very important for applications like autonomous driving and digital twins of cities. However, current deep learning models suffer from a significant generalization gap. Unsupervised Domain Adaptation methods have recently emerged to tackle this issue. While domain-invariant feature learning using Maximum Mean Discrepancy has shown promise for images due to its simplicity, its application remains unexplored in outdoor mobile mapping point clouds. Moreover, previous methods do not consider the class information, which can lead to suboptimal adaptation performance. We propose a new approach-Contrastive Maximum Mean Discrepancy-to maximize intra-class domain alignment and minimize inter-class domain discrepancy, and integrate it into a 3D semantic segmentation model for LiDAR point clouds. The evaluation of our method with large-scale UDA datasets shows that it surpasses state-of-the-art UDA approaches for 3D LiDAR point clouds. CMMD is a promising UDA approach with strong potential for point cloud semantic segmentation.