无需已知脉冲形状,实现连续时空的高精度时间飞行成像。
Blind Time-of-Flight Imaging: Sparse Deconvolution on the Continuum with Unknown Kernels
- 基于近似满足斯特兰格-弗克斯条件的物理脉冲特性,设计盲反卷积算法。
- 在多种实际场景中实现与已知脉冲相当的超分辨率性能。
- 适用于光在飞行中、非视域等复杂成像任务,无需校准脉冲形状。
近年来,计算时间飞行(ToF)成像作为一种新兴成像模态,为自然场景提供了新的强大解析方式,广泛应用于三维成像、光在飞行中成像及非视域成像。数学上,ToF成像依赖于算法超分辨率,因为回波光信号在时间上比数字设备可捕捉的分辨率更精细。传统方法需已知发射光脉冲或核函数,并采用稀疏反卷积恢复场景。本文提出一种新颖的盲ToF成像技术,无需核函数校准,可在连续时间上恢复稀疏脉冲,而非离散网格。通过分析各类ToF模态的共性,我们发现多数物理脉冲近似满足逼近论中的斯特兰格-弗克斯条件,从而构建新的稀疏超分辨率数学模型。恢复方法采用基于交替优化的算法。我们在不同ToF模态下对传统校准方法进行基准测试,硬件实验表明本方法具有算法优势、灵活性和实证鲁棒性。结果表明,即使在难以区分紧密物体的情况下,仍能实现超分辨率,且性能接近已知核情形。光在飞行中成像与光扫视频实例展示了该盲超分辨率方法在提升自然场景理解方面的实际价值。
原文摘要 · Abstract (English)
In recent years, computational Time-of-Flight (ToF) imaging has emerged as an exciting and a novel imaging modality that offers new and powerful interpretations of natural scenes, with applications extending to 3D, light-in-flight, and non-line-of-sight imaging. Mathematically, ToF imaging relies on algorithmic super-resolution, as the back-scattered sparse light echoes lie on a finer time resolution than what digital devices can capture. Traditional methods necessitate knowledge of the emitted light pulses or kernels and employ sparse deconvolution to recover scenes. Unlike previous approaches, this paper introduces a novel, blind ToF imaging technique that does not require kernel calibration and recovers sparse spikes on a continuum, rather than a discrete grid. By studying the shared characteristics of various ToF modalities, we capitalize on the fact that most physical pulses approximately satisfy the Strang-Fix conditions from approximation theory. This leads to a new mathematical formulation for sparse super-resolution. Our recovery approach uses an optimization method that is pivoted on an alternating minimization strategy. We benchmark our blind ToF method against traditional kernel calibration methods, which serve as the baseline. Extensive hardware experiments across different ToF modalities demonstrate the algorithmic advantages, flexibility and empirical robustness of our approach. We show that our work facilitates super-resolution in scenarios where distinguishing between closely spaced objects is challenging, while maintaining performance comparable to known kernel situations. Examples of light-in-flight imaging and light-sweep videos highlight the practical benefits of our blind super-resolution method in enhancing the understanding of natural scenes.
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