Passive non-line-of-sight imaging methods are often faster and stealthier than their active counterparts, requiring less complex and costly equipment. However, many of these methods exploit motion of an occluder or the hidden scene, or require knowledge or calibration of complicated occluders. The edge of a wall is a known and ubiquitous occluding structure that may be used as an aperture to image the region hidden behind it. Light from around the corner is cast onto the floor forming a fan-like penumbra rather than a sharp shadow. Subtle variations in the penumbra contain a remarkable amount of information about the hidden scene. Previous work has leveraged the vertical nature of the edge to demonstrate 1D (in angle measured around the corner) reconstructions of moving and stationary hidden scenery from as little as a single photograph of the penumbra. In this work, we introduce a second reconstruction dimension: range measured from the edge. We derive a new forward model, accounting for radial falloff, and propose two inversion algorithms to form 2D reconstructions from a single photograph of the penumbra. Performances of both algorithms are demonstrated on experimental data corresponding to several different hidden scene configurations. A Cramér–Rao bound analysis further demonstrates the feasibility (and utility) of the 2D corner camera.

中文翻译：

---

来自单边遮挡器的二维非视线场景估计

被动非视距成像方法通常比主动成像方法更快、更隐蔽，需要的设备复杂性和成本更低。然而，许多这些方法利用遮挡物或隐藏场景的运动，或者需要复杂遮挡物的知识或校准。墙的边缘是一种已知且无处不在的遮挡结构，可以用作孔来对隐藏在其后面的区域进行成像。拐角处的光线投射到地板上，形成扇形半影而不是锐利的阴影。半影的细微变化包含了大量关于隐藏场景的信息。以前的工作利用边缘的垂直特性来展示从半影的单张照片中对移动和静止隐藏风景的一维（在拐角处测量的角度）重建。在这项工作中，我们引入了第二个重建维度：从边缘测量的范围。我们推导出了一个新的前向模型，考虑了径向衰减，并提出了两种反演算法，以从半影的单张照片中形成 2D 重建。两种算法的性能都在对应于几种不同隐藏场景配置的实验数据上得到了证明。Cramér-Rao 边界分析进一步证明了 2D 角相机的可行性（和实用性）。考虑到径向衰减，并提出了两种反演算法，以从半影的单张照片中形成二维重建。两种算法的性能都在对应于几种不同隐藏场景配置的实验数据上得到了证明。Cramér-Rao 边界分析进一步证明了 2D 角相机的可行性（和实用性）。考虑到径向衰减，并提出了两种反演算法，以从半影的单张照片中形成二维重建。两种算法的性能都在对应于几种不同隐藏场景配置的实验数据上得到了证明。Cramér-Rao 边界分析进一步证明了 2D 角相机的可行性（和实用性）。