We consider the non-line-of-sight (NLOS) imaging of an object using the light reflected off a diffusive wall. The wall scatters incident light such that a lens is no longer useful to form an image. Instead, we exploit the 4D spatial coherence function to reconstruct a 2D projection of the obscured object. The approach is completely passive in the sense that no control over the light illuminating the object is assumed and is compatible with the partially coherent fields ubiquitous in both the indoor and outdoor environments. We formulate a multi-criteria convex optimization problem for reconstruction, which fuses the reflected field's intensity and spatial coherence information at different scales. Our formulation leverages established optics models of light propagation and scattering and exploits the sparsity common to many images in different bases. We also develop an algorithm based on the alternating direction method of multipliers to efficiently solve the convex program proposed. A means for analyzing the null space of the measurement matrices is provided as well as a means for weighting the contribution of individual measurements to the reconstruction. This paper holds promise to advance passive imaging in the challenging NLOS regimes in which the intensity does not necessarily retain distinguishable features and provides a framework for multi-modal information fusion for efficient scene reconstruction.

中文翻译：

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多模态非视距被动成像


我们考虑使用漫射壁反射的光对物体进行非视距 （NLOS） 成像。墙壁会散射入射光，因此透镜不再可用于形成图像。相反，我们利用 4D 空间相干函数来重建被遮挡物体的 2D 投影。该方法是完全被动的，因为没有假设对照亮物体的光线进行控制，并且与室内和室外环境中普遍存在的部分相干场兼容。我们制定了一个用于重建的多准则凸优化问题，该问题融合了不同尺度下反射场的强度和空间相干信息。我们的公式利用了已建立的光传播和散射光学模型，并利用了不同基中许多图像共有的稀疏性。我们还开发了一种基于乘子交替方向法的算法，以有效地求解所提出的凸方案。提供了一种分析测量矩阵的零空间的方法，以及一种对单个测量对重建的贡献进行加权的方法。本文有望在具有挑战性的 NLOS 机制中推进被动成像，其中强度不一定保留可区分的特征，并为多模态信息融合提供框架以实现高效的场景重建。