Exploring Scene Affinity for Semi-Supervised LiDAR Semantic Segmentation

TL;DR

This paper introduces AIScene, a semi-supervised LiDAR segmentation method that leverages scene affinity, a point erasure strategy, and scene-level augmentation to improve performance in driving scenes.

Contribution

AIScene proposes a novel point erasure and scene augmentation approach that enhances semi-supervised LiDAR segmentation by utilizing intra- and inter-scene consistency.

Findings

Outperforms previous methods on benchmark datasets.

Achieves 1.9% and 2.1% improvements with 1% labeled data.

Effective in semi-supervised LiDAR segmentation tasks.

Abstract

This paper explores scene affinity (AIScene), namely intra-scene consistency and inter-scene correlation, for semi-supervised LiDAR semantic segmentation in driving scenes. Adopting teacher-student training, AIScene employs a teacher network to generate pseudo-labeled scenes from unlabeled data, which then supervise the student network's learning. Unlike most methods that include all points in pseudo-labeled scenes for forward propagation but only pseudo-labeled points for backpropagation, AIScene removes points without pseudo-labels, ensuring consistency in both forward and backward propagation within the scene. This simple point erasure strategy effectively prevents unsupervised, semantically ambiguous points (excluded in backpropagation) from affecting the learning of pseudo-labeled points. Moreover, AIScene incorporates patch-based data augmentation, mixing multiple scenes at both scene and instance levels. Compared to existing augmentation techniques that typically perform scene-level mixing between two scenes, our method enhances the semantic diversity of labeled (or pseudo-labeled) scenes, thereby improving the semi-supervised performance of segmentation models. Experiments show that AIScene outperforms previous methods on two popular benchmarks across four settings, achieving notable improvements of 1.9% and 2.1% in the most challenging 1% labeled data.