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arXiv 2607.00514cs.CVcs.AI

Cross4D-JEPA: 用于4D点云表示学习的密集跨模态对应蒸馏

Cross4D-JEPA: Dense Cross-modal Correspondence Distillation for 4D Point Cloud Representation Learning

Nagoya University(名古屋大学);Northeastern University(东北大学);KC Machine Learning Lab(KC机器学习实验室);University of Science, Vietnam National University Ho Chi Minh City(胡志明市越南国立大学理科大学);University of California, Los Angeles(加州大学洛杉矶分校)

Trung Thanh Nguyen, Hai Nguyen-Truong, Tu Vo, Hoang M. Truong, Tuan-Anh Vu

AI总结:

提出Cross4D-JEPA,通过教师-学生框架将冻结的2D基础模型(如DINOv2或V-JEPA 2)的密集补丁特征蒸馏到4D点编码器,实现每点对应和潜在空间匹配,在四个基准上优于模态内和全局跨模态基线。

摘要:

动态4D点云(由深度传感器和LiDAR随时间捕获的3D点序列)的自动理解是机器人和具身感知的核心。然而,密集标注它们成本高昂,使得自监督预训练成为可迁移表示的自然途径。然而,现有的预文本任务几乎完全是模态内的,少数从2D基础模型迁移知识的方法依赖于每个片段单个全局嵌入,丢弃了这些模型计算的丰富每补丁语义。为了解决这一差距,我们提出了Cross4D-JEPA,一种教师-学生方法,将冻结的2D基础模型(图像模型DINOv2或视频模型V-JEPA 2)蒸馏到4D点编码器中。所提出的方法结合了(1)密集跨模态对应,将每个3D点映射到其投影到的教师补丁特征,以及(2)每点目标,训练学生在潜在空间中匹配这些特征,无需掩码、负样本或解码器。我们在四个基准(MSR-Action3D、DeformingThings4D、NTU-RGB+D 60和HOI4D)上评估了Cross4D-JEPA,与模态内和全局跨模态基线进行比较。实验结果表明,在匹配协议下,所提出的方法在四个基准上始终优于模态内和全局跨模态基线,并且与更重的已发表4D方法竞争;进一步分析表明,这一增益主要归因于对应的粒度而非教师模态。除了识别精度外,Cross4D-JEPA学习的密集表示跨领域迁移,提高了标签效率,并在相同训练预算下改善了全标签微调,同时一个13倍小的编码器匹配了重量的池化骨干网络。

英文摘要:

Automatic understanding of dynamic 4D point clouds, the 3D-point sequences captured over time by depth sensors and LiDAR, is central to robotics and embodied perception. Yet annotating them densely is expensive, making self-supervised pretraining the natural route to transferable representations. Existing pretext tasks, however, are almost entirely intra-modal, and the few methods that transfer knowledge from 2D foundation models rely on a single global embedding per clip, discarding the rich per-patch semantics that these models compute. To address this gap, we propose Cross4D-JEPA, a teacher-student method that distills a frozen 2D foundation model, an image model DINOv2, or a video model V-JEPA 2, into a 4D point encoder. The proposed method combines (1) a dense cross-modal correspondence that maps every 3D point to the teacher patch feature it projects to, and (2) a per-point objective that trains the student to match these features in latent space with no masking, negatives, or decoder. We evaluate Cross4D-JEPA on four benchmarks, MSR-Action3D, DeformingThings4D, NTU-RGB+D 60, and HOI4D, against intra-modal and global cross-modal baselines. Experimental results show that, under a matched protocol, the proposed method consistently outperforms intra-modal and global cross-modal baselines across the four benchmarks and is competitive with heavier published 4D methods; further analysis attributes this gain primarily to the granularity of the correspondence rather than the teacher modality. Beyond recognition accuracy, the dense representation learned by Cross4D-JEPA transfers across domains, improves label efficiency, and improves full-label fine-tuning under the same training budget, while a 13x smaller encoder matches a heavyweight pooling backbone.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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