用简单方法实现2D视觉模型向3D LiDAR模型的知识迁移,无需伪语义图。
CleverDistiller: Simple and Spatially Consistent Cross-modal Distillation
- 直接使用特征相似性损失+MLP投影头,避免复杂损失设计。
- 在低数据量下仍提升10% mIoU,优于现有方法。
- 新增占用预测任务增强3D空间推理能力,适合自动驾驶场景。
视觉基础模型(如DINO)推动了基于2D相机感知的范式转变,能提取通用特征支持多种下游任务。近期工作通过自监督跨模态知识蒸馏(KD)将这些泛化能力迁移到3D LiDAR模型中,但多依赖复杂损失、伪语义图或仅限于语义分割任务。本文提出CleverDistiller,一种自监督的2D到3D跨模态蒸馏框架,采用简单有效的设计:不依赖对比学习的复杂损失,而是结合直接特征相似性损失与MLP投影头,使3D网络学习复杂的语义依赖关系;关键在于无需伪语义图,可直接从视觉基础模型迁移知识而无需显式语义监督。此外,引入辅助自监督空间任务——占用预测,以增强通过蒸馏获得的语义知识的3D空间推理能力。在标准自动驾驶基准上进行的2D到3D KD实验表明,该方法在语义分割和3D目标检测(3DOD)上均达到最新水平,尤其在微调时仅用极少数据即提升最高达10%的mIoU,验证了其简单却高效的知识蒸馏策略的有效性。
原文摘要 · Abstract (English)
Vision foundation models (VFMs) such as DINO have led to a paradigm shift in 2D camera-based perception towards extracting generalized features to support many downstream tasks. Recent works introduce self-supervised cross-modal knowledge distillation (KD) as a way to transfer these powerful generalization capabilities into 3D LiDAR-based models. However, they either rely on highly complex distillation losses, pseudo-semantic maps, or limit KD to features useful for semantic segmentation only. In this work, we propose CleverDistiller, a self-supervised, cross-modal 2D-to-3D KD framework introducing a set of simple yet effective design choices: Unlike contrastive approaches relying on complex loss design choices, our method employs a direct feature similarity loss in combination with a multi layer perceptron (MLP) projection head to allow the 3D network to learn complex semantic dependencies throughout the projection. Crucially, our approach does not depend on pseudo-semantic maps, allowing for direct knowledge transfer from a VFM without explicit semantic supervision. Additionally, we introduce the auxiliary self-supervised spatial task of occupancy prediction to enhance the semantic knowledge, obtained from a VFM through KD, with 3D spatial reasoning capabilities. Experiments on standard autonomous driving benchmarks for 2D-to-3D KD demonstrate that CleverDistiller achieves state-of-the-art performance in both semantic segmentation and 3D object detection (3DOD) by up to 10% mIoU, especially when fine tuning on really low data amounts, showing the effectiveness of our simple yet powerful KD strategy
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