mmWaveFlow: Unified Enhancement and Generation of mmWave Human Point Clouds

Abstract

Millimeter-wave (mmWave) point clouds have attracted increasing interest in human sensing due to their robustness, privacy preservation, and low cost. However, their practical adoption is hindered by the inherent sparsity of data and the lack of large-scale annotated dataset. We revisit generative modeling and propose a unified flow-matching framework mmWaveFlow that unifies enhancement and generation of mmWave point clouds by learning an invertible transport between dense and sparse point clouds. We leverage paired data and a Cross-modal Latent Alignment module to enforce semantic alignment and bridge the modality gap. We find that condition-free flow matching is more vulnerable to latent path crossings, which impair transport. Therefore, we propose Origin-Aware Flow Matching (OA-Flow) by conditioning transport on the path origin to mitigate ambiguity in bidirectional transport. Results of experiments across multiple datasets demonstrate the effectiveness of mmWaveFlow for mmWave human point clouds generation and enhancement. We also observe consistent gains in downstream tasks, highlighting the promise of our framework for human sensing. Codes are available at https://github.com/suchang-99/mmWaveFlow.