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arXiv 2307.12972cs.CV

DFA3D:用于2D到3D特征提升的3D可变形注意力

DFA3D: 3D Deformable Attention For 2D-to-3D Feature Lifting

South China University of Technology(华南理工大学);The Hong Kong University of Science and Technology(香港科技大学);International Digital Economy Academy (IDEA)(国际数字经济研究院(IDEA));Tsinghua University(清华大学)

Hongyang Li, Hao Zhang, Zhaoyang Zeng, Shilong Liu, Feng Li, Tianhe Ren, Lei Zhang

AI总结:

针对现有2D到3D特征提升方法存在的无特征细化或深度模糊问题,提出新型算子DFA3D,通过深度扩展加3D可变形注意力聚合特征,在nuScenes数据集上实现显著性能提升。

摘要:

本文提出了一种名为3D可变形注意力(DFA3D)的新型算子,用于2D到3D特征提升,该任务将多视图2D图像特征转换到统一的3D空间以进行3D目标检测。现有的特征提升方法,例如基于Lift-Splat的方法和基于2D注意力的方法,要么使用估计的深度得到伪激光雷达特征,再将它们投射到3D空间中,这是一种无特征细化的单次操作;要么忽略深度,通过2D注意力机制提升特征,这类方法能获得更精细的语义信息,但存在深度模糊问题。相比之下,我们基于DFA3D的方法首先利用估计的深度将每个视图的2D特征图扩展到3D,随后利用DFA3D从扩展后的3D特征图中聚合特征。得益于类Transformer架构,DFA3D可从根源上有效缓解深度模糊问题,且提升后的特征可逐层逐步细化。此外,我们提出了DFA3D的一种数学等价实现方式,能显著提升其内存效率和计算速度。我们仅通过少量代码修改,就将DFA3D集成到多种使用基于2D注意力的特征提升的方法中,并在nuScenes数据集上进行评估。实验结果显示,该方法平均能带来+1.41% mAP的稳定提升,当有高质量深度信息可用时,mAP提升最高可达+15.1%,证明了DFA3D的优越性、适用性和巨大潜力。代码可在https://github.com/IDEA-Research/3D-deformable-attention.git获取。

英文摘要:

In this paper, we propose a new operator, called 3D DeFormable Attention (DFA3D), for 2D-to-3D feature lifting, which transforms multi-view 2D image features into a unified 3D space for 3D object detection. Existing feature lifting approaches, such as Lift-Splat-based and 2D attention-based, either use estimated depth to get pseudo LiDAR features and then splat them to a 3D space, which is a one-pass operation without feature refinement, or ignore depth and lift features by 2D attention mechanisms, which achieve finer semantics while suffering from a depth ambiguity problem. In contrast, our DFA3D-based method first leverages the estimated depth to expand each view's 2D feature map to 3D and then utilizes DFA3D to aggregate features from the expanded 3D feature maps. With the help of DFA3D, the depth ambiguity problem can be effectively alleviated from the root, and the lifted features can be progressively refined layer by layer, thanks to the Transformer-like architecture. In addition, we propose a mathematically equivalent implementation of DFA3D which can significantly improve its memory efficiency and computational speed. We integrate DFA3D into several methods that use 2D attention-based feature lifting with only a few modifications in code and evaluate on the nuScenes dataset. The experiment results show a consistent improvement of +1.41\% mAP on average, and up to +15.1\% mAP improvement when high-quality depth information is available, demonstrating the superiority, applicability, and huge potential of DFA3D. The code is available at https://github.com/IDEA-Research/3D-deformable-attention.git.

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