The light transport matrix (LTM) is an instrumental tool in line-of-sight (LOS) imaging, describing how light interacts with the scene and enabling applications such as relighting or separation of illumination components. We introduce a framework to estimate the LTM of non-line-of-sight (NLOS) scenarios, coupling recent virtual forward light propagation models for NLOS imaging with the LOS light transport equation. We design computational projector-camera setups, and use these virtual imaging systems to estimate the transport matrix of hidden scenes. We introduce the specific illumination functions to compute the different elements of the matrix, overcoming the challenging wide-aperture conditions of NLOS setups. Our NLOS light transport matrix allows us to (re)illuminate specific locations of a hidden scene, and separate direct, first-order indirect, and higher-order indirect illumination of complex cluttered hidden scenes, similar to existing LOS techniques.

翻译：光运输矩阵(LTM)是视觉成像(LLOS)的一个工具,它描述了光与场景的相互作用,以及照明或分离照明部件等赋能应用。我们引入了一个框架来估计非视觉情景(NLOS)的LTM(LTM),将NLOS图像最近的虚拟前方光传播模型与LLOS轻型运输方程结合起来。我们设计了计算投影摄像仪设置,并使用这些虚拟成像系统来估计隐藏场景的迁移矩阵。我们引入了特定的照明功能来计算矩阵的不同元素,克服NLOS设置的具有挑战性的宽孔条件。我们的NLOS光运输矩阵允许我们(重新)点亮隐藏场的具体位置,并分离出与现有的LLOS技术相似的复杂包罗的隐藏场景的直接、第一顺序间接和更高层次间接污染。