用流模型实现雷达人体姿态实时多解估计,精度与可靠性双提升。
You Only Flow Once: Calibrated and Real-Time Radar Pose Estimation with Multi-Hypothesis Normalizing Flows

- 基于条件流模型并行生成多姿态分布,无需迭代采样。
- 在三个数据集上精度优于扩散模型,推理速度超20倍,校准误差降85%。
- 适合需要实时性与可信不确定性的智能安防、自动驾驶场景。
稀疏且噪声严重的毫米波雷达点云常对应多个合理的人体姿态,使确定性姿态估计本质上病态。现有方法仍为确定性,将歧义压缩为单一估计。基于扩散的方法虽可建模多解分布,但需逐样本串行去噪且缺乏校准不确定性。本文提出多假设归一化流姿态生成器(MH-NFPG),通过条件归一化流从雷达点云建模姿态分布。具体地,结合时空变换器主干与归一化流,将拉普拉斯基分布映射为丰富后验分布,仅通过一次前向传播即可并行生成。利用此高效性,我们在三个雷达基准(MM-Fi、mmRadPose、mRI)上均优于扩散模型的校准性能,两项任务精度提升,一项持平,同时实现超过20倍的推理加速,并将校准误差降低高达85%。发现扩散模型校准性能显著下降,而本方法在跨环境设置下仍保持可靠覆盖。结果表明,归一化流是实时、带不确定性的雷达姿态估计中扩散模型的可行替代方案。代码将公开。
原文摘要 · Abstract (English)
Sparse and noisy millimeter-wave radar point cloud observations often correspond to multiple plausible human poses, making deterministic pose estimation fundamentally ill-posed. Yet existing radar methods remain deterministic, collapsing this ambiguity into a single estimate. Diffusion-based alternatives can model multi-hypothesis distributions but require costly sequential denoising for each distribution sample and lack calibrated uncertainty. We propose Multi-Hypothesis Normalizing Flow Pose Generator (MH-NFPG), which models pose distributions from radar point clouds using a conditional normalizing flow. Specifically, we combine a spatiotemporal transformer backbone with a normalizing flow that transforms a Laplace base distribution into an expressive posterior, generated in parallel through a single forward pass. Leveraging this efficiency, we outperform diffusion-based alternatives in calibration across three radar benchmarks (MM-Fi, mmRadPose, mRI), improve pose accuracy on two, and match it on the third, while achieving over 20x faster inference for applications and reducing calibration error by up to 85%. We find that calibration degrades substantially for diffusion models, whereas our flow-based approach maintains reliable coverage, also in cross-environment settings. These results demonstrate normalizing flows as a practical alternative to diffusion models for real-time, uncertainty-aware radar pose estimation. Our code will be made publicly available.
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