arXiv:2607.10762cs.CVcs.LG2026-07中稿 · The IEEE/RSJ Inter…

用视觉模型蒸馏引导激光雷达预训练,解决跨模态与架构差异问题。

TOLiD: Bridging the Architecture Gap in Vision Foundation Model to LiDAR Pretraining via Token Lifting for Distillation

论文配图:TOLiD: Bridging the Architecture Gap in Vision Foundation Model to LiDAR Pretraining via Token Lifting for Distillation
图 1 · 摘自论文原文
  • 将图像块特征转化为点云对应令牌,实现跨模态对齐。
  • 在五个数据集上验证,冻结主干时仍显著提升迁移性能。
  • 适合做激光雷达单模态部署的轻量级模型训练。

将视觉基础模型(VFMs)用于激光雷达骨干网络的自监督预训练,可减少对密集点级标注的依赖。然而现有方法通常将视觉模型视为固定特征源,训练异构3D骨干网络去匹配固定的图像嵌入,导致学生网络需同时克服模态差异和架构差异——即稠密的ViT令牌表示与稀疏3D编码器之间的鸿沟。本文提出TOLiD,通过将每个图像块视锥内的点特征经视锥池化与注意力操作转换为单一令牌,并在兼容的块-令牌表示上进行蒸馏,结合可见性掩码实现令牌级监督。针对纯激光雷达部署,采用带掩码的双线性采样将令牌特征回映至点级表示,避免低点数区域的影响。在五个异构激光雷达数据集及四组跨传感器适配任务上评估,TOLiD在冻结主干与轻量头的情况下均展现出优异的迁移能力。

原文摘要 · Abstract (English)

Cross-modal distillation from Vision Foundation Models (VFMs) to LiDAR backbones has recently emerged as a self-supervised pretraining strategy that reduces reliance on dense point-wise annotation for 3D scene understanding. However, existing distillation pipelines typically treat the VFM as a frozen feature source and train a heterogeneous 3D backbone to match fixed image embeddings, forcing the student to bridge both the modality gap and the cross-architecture gap between dense ViT token representations and sparse 3D encoders. We propose TOLiD, a self-supervised pretraining method for LiDAR representation learning that addresses this gap by coupling a LiDAR backbone with a student Vision Transformer (ViT) initialized from a frozen VFM teacher and applying supervision over compatible patch-token representations. TOLiD converts the set of point features within each image patch frustum into a token using Frustum Pooling followed by Frustum Attention, and performs token-level distillation with visibility masking. For LiDAR-only deployment, we lift token features back to per-point representations using masked bilinear sampling to avoid patches that have limited LiDAR points. We extensively evaluate TOLiD on five heterogeneous LiDAR datasets and four cross-sensor adaptation pairs, demonstrating improved transfer with frozen backbones and lightweight heads.

激光雷达自监督模型蒸馏跨模态

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